Endocrinology

More than 50% of obese adolescents met criteria for depression, which also was associated with several components of metabolic syndrome, based on data from 160 individuals.

Previous research shows that the metabolic consequences of obesity are worsened with the coexistence of depression in adults, but a similar relationship in obese adolescents has not been explored, according to Nisha Gupta, a medical student at the University of Texas Health Science Center, Houston, and colleagues.

“This relationship is explained by an overactive stress response and adoption of unhealthy lifestyle habits,” both of which increased during the COVID-19 pandemic, the researchers noted in their abstract.

In a study presented at the Pediatric Academic Societies annual meeting, the researchers reviewed data from 160 obese adolescents seen at a pediatric weight management clinic between July 1, 2018, and Dec. 3, 2021. The data included anthropometric, clinical, and laboratory information. Depression was assessed using the Patient Health Questionnaire–9 (PHQ-9). The goal of the study was to compare the prevalence of metabolic syndrome components in obese youth with and without diagnosed depression.

Overall, 46% of the patients had PHQ-9 scores less than 5, which was defined as no clinically significant depression. A total of 26% had current or prior diagnoses of depression, and 25% met the criteria for moderate to severe depression, with PHQ-9 scores of 10 or higher. Notably, 18% of individuals with no prior history of depression met criteria for moderate to severe depression, the researchers wrote.

Teens who reported daytime fatigue or trouble sleeping, and those who reported eating out seven or more times a week had higher scores than those without these reports.

In laboratory analyses, higher PHQ-9 scores were significantly associated with increasing weight, body mass index, body fat percentage, diastolic blood pressure, and fasting blood insulin (P < .02 for all).

The study findings were limited by the relatively small sample size, the researchers noted. However, the results suggest that depression is common, but often underdiagnosed in obese adolescents, and depression screening should be part of obesity management.
 

Study highlights need to screen

The current study is important because of the overall increase in obesity in the United States, which extends to children and teens, Tim Joos, MD, a Seattle-based clinician with a combination internal medicine/pediatrics practice, said in an interview.

“With skyrocketing rates of obesity among children and teens over the last decades, we are seeing more ‘adult’ diseases seep into the younger ages, including type 2 diabetes, high blood pressure and now, depression,” he said.

“The results are a wake-up call for the need for better system-wide prevention and management of obesity in adolescents and the importance of screening and managing depression in obese teenagers,” he emphasized.

The study received no outside funding. The researchers had no financial conflicts to disclose. Dr. Joos had no financial conflicts to disclose and serves on the editorial advisory board of Pediatric News.

More than 50% of obese adolescents met criteria for depression, which also was associated with several components of metabolic syndrome, based on data from 160 individuals.

Previous research shows that the metabolic consequences of obesity are worsened with the coexistence of depression in adults, but a similar relationship in obese adolescents has not been explored, according to Nisha Gupta, a medical student at the University of Texas Health Science Center, Houston, and colleagues.

“This relationship is explained by an overactive stress response and adoption of unhealthy lifestyle habits,” both of which increased during the COVID-19 pandemic, the researchers noted in their abstract.

In a study presented at the Pediatric Academic Societies annual meeting, the researchers reviewed data from 160 obese adolescents seen at a pediatric weight management clinic between July 1, 2018, and Dec. 3, 2021. The data included anthropometric, clinical, and laboratory information. Depression was assessed using the Patient Health Questionnaire–9 (PHQ-9). The goal of the study was to compare the prevalence of metabolic syndrome components in obese youth with and without diagnosed depression.

Overall, 46% of the patients had PHQ-9 scores less than 5, which was defined as no clinically significant depression. A total of 26% had current or prior diagnoses of depression, and 25% met the criteria for moderate to severe depression, with PHQ-9 scores of 10 or higher. Notably, 18% of individuals with no prior history of depression met criteria for moderate to severe depression, the researchers wrote.

Teens who reported daytime fatigue or trouble sleeping, and those who reported eating out seven or more times a week had higher scores than those without these reports.

In laboratory analyses, higher PHQ-9 scores were significantly associated with increasing weight, body mass index, body fat percentage, diastolic blood pressure, and fasting blood insulin (P < .02 for all).

The study findings were limited by the relatively small sample size, the researchers noted. However, the results suggest that depression is common, but often underdiagnosed in obese adolescents, and depression screening should be part of obesity management.
 

Study highlights need to screen

The current study is important because of the overall increase in obesity in the United States, which extends to children and teens, Tim Joos, MD, a Seattle-based clinician with a combination internal medicine/pediatrics practice, said in an interview.

“With skyrocketing rates of obesity among children and teens over the last decades, we are seeing more ‘adult’ diseases seep into the younger ages, including type 2 diabetes, high blood pressure and now, depression,” he said.

“The results are a wake-up call for the need for better system-wide prevention and management of obesity in adolescents and the importance of screening and managing depression in obese teenagers,” he emphasized.

The study received no outside funding. The researchers had no financial conflicts to disclose. Dr. Joos had no financial conflicts to disclose and serves on the editorial advisory board of Pediatric News.

More than 50% of obese adolescents met criteria for depression, which also was associated with several components of metabolic syndrome, based on data from 160 individuals.

Previous research shows that the metabolic consequences of obesity are worsened with the coexistence of depression in adults, but a similar relationship in obese adolescents has not been explored, according to Nisha Gupta, a medical student at the University of Texas Health Science Center, Houston, and colleagues.

“This relationship is explained by an overactive stress response and adoption of unhealthy lifestyle habits,” both of which increased during the COVID-19 pandemic, the researchers noted in their abstract.

In a study presented at the Pediatric Academic Societies annual meeting, the researchers reviewed data from 160 obese adolescents seen at a pediatric weight management clinic between July 1, 2018, and Dec. 3, 2021. The data included anthropometric, clinical, and laboratory information. Depression was assessed using the Patient Health Questionnaire–9 (PHQ-9). The goal of the study was to compare the prevalence of metabolic syndrome components in obese youth with and without diagnosed depression.

Overall, 46% of the patients had PHQ-9 scores less than 5, which was defined as no clinically significant depression. A total of 26% had current or prior diagnoses of depression, and 25% met the criteria for moderate to severe depression, with PHQ-9 scores of 10 or higher. Notably, 18% of individuals with no prior history of depression met criteria for moderate to severe depression, the researchers wrote.

Teens who reported daytime fatigue or trouble sleeping, and those who reported eating out seven or more times a week had higher scores than those without these reports.

In laboratory analyses, higher PHQ-9 scores were significantly associated with increasing weight, body mass index, body fat percentage, diastolic blood pressure, and fasting blood insulin (P < .02 for all).

The study findings were limited by the relatively small sample size, the researchers noted. However, the results suggest that depression is common, but often underdiagnosed in obese adolescents, and depression screening should be part of obesity management.
 

Study highlights need to screen

The current study is important because of the overall increase in obesity in the United States, which extends to children and teens, Tim Joos, MD, a Seattle-based clinician with a combination internal medicine/pediatrics practice, said in an interview.

“With skyrocketing rates of obesity among children and teens over the last decades, we are seeing more ‘adult’ diseases seep into the younger ages, including type 2 diabetes, high blood pressure and now, depression,” he said.

“The results are a wake-up call for the need for better system-wide prevention and management of obesity in adolescents and the importance of screening and managing depression in obese teenagers,” he emphasized.

The study received no outside funding. The researchers had no financial conflicts to disclose. Dr. Joos had no financial conflicts to disclose and serves on the editorial advisory board of Pediatric News.

Patients who receive parathyroidectomy for mild primary hyperparathyroidism show no benefits in survival or morbidity, including fractures, cancer, or cardiovascular outcomes over more than 10 years, compared with those not receiving the surgery, results from a randomized, prospective trial show.

“In contrast to existing data showing increased mortality and cardiovascular morbidity in mild primary hyperparathyroidism, we did not find any treatment effect of parathyroidectomy on these important clinical endpoints,” report the authors of the study, published in the Annals of Internal Medicine.
 

Reason to evaluate and revise current recommendations?

With mild primary hyperparathyroidism becoming the predominant form of hyperparathyroidism, the results suggest rethinking the current recommendations for the condition, the study authors note. 

“Over the years, more active management of mild primary hyperparathyroidism has been recommended, with a widening of criteria for parathyroidectomy,” they write.

“With the low number of kidney stones (n = 5) and no effect of parathyroidectomy on fractures, there may be a need to evaluate and potentially revise the current recommendations.”

The authors of an accompanying editorial agree that “the [results] provide a strong rationale for nonoperative management of patients with mild primary hyperparathyroidism.”

“The findings suggest that most patients can be managed nonoperatively, with monitoring of serum calcium levels every 1 to 2 years or if symptoms occur,” write the editorial authors, Mark J. Bolland, PhD, and Andrew Grey, MD, of the department of medicine, University of Auckland, New Zealand.

Although parathyroidectomy is recommended for the treatment in patients with hyperparathyroidism with severe hypercalcemia or overt symptoms, there has been debate on the long-term benefits of surgery among those with milder cases.  

Most previous studies that have shown benefits, such as reductions in the risk of fracture with parathyroidectomy, have importantly not distinguished between mild and more severe primary hyperparathyroidism, the authors note.
 

No significant differences in mortality between surgery, nonsurgery groups

For the Scandinavian Investigation of Primary Hyperparathyroidism (SIPH) trial, first author Mikkel Pretorius, MD, Oslo University Hospital and Faculty of Medicine, University of Oslo, and colleagues enrolled 191 patients between 1998 and 2005 in Sweden, Norway, and Denmark, who were aged 50-80 years and had mild primary hyperparathyroidism, defined as serum calcium levels of 10.42-11.22 mg/dL.

Participants were randomized to receive surgery (n = 95) or nonoperative observation without intervention (n = 96).

After a 10-year follow-up, 129 patients had completed the final visit. The overall death rate was 7.6%, and, with eight deaths in the surgery group and seven in the nonsurgery group, there were no significant differences between groups in terms of mortality (HR, 1.17; P = .76).

During an extended observation period that lasted until 2018, mortality rates increased by 23%, but with a relatively even distribution of 24 deaths in the surgery group and 20 among those with no surgery.

Chronic hypercalcemia related to primary hyperparathyroidism has been debated as being associated with an increased risk of cardiovascular disease or cancer, however, “the absolute numbers for these and the other disease-specific causes of death were nearly identical between groups,” the authors write, with 17 deaths from cardiovascular disease, eight from cancer, and eight from cerebrovascular disease.

In terms of morbidity, including cardiovascular events, cerebrovascular events, cancer, peripheral fractures, and renal stones, there were 101 events overall, with 52 in the parathyroidectomy group and 49 in the nonsurgery group, which again, was not a significant difference.

Sixteen vertebral fractures occurred overall in 14 patients, which were evenly split at seven patients in each group.

The authors note that “the incidence of peripheral fractures for women in our study was around 2,900 per 100,000 person-years, in the same range as for 70-year-old women in a study in Gothenburg, Sweden (about 2,600 per 100,000 person-years).”

There were no between-group differences in terms of time to death or first morbidity event for any of the prespecified events.

Of the 96 patients originally assigned to the nonsurgery group, 17 (18%) had surgery during follow-up, including three for serious hypercalcemia, three by their own choice, two for decreasing bone density, one for kidney stones, and the others for unclear or unrelated reasons.

Study limitations include that only 26 men (13 in each group) were included, and only 16 completed the study. “The external validity for men based on this study is therefore limited,” the authors note.

And although most people with primary hyperparathyroidism are adults, the older age of participants suggests the results should not be generalized to younger patients with benign parathyroid tumors.

The editorialists note that age should be one of the few factors that may, indeed, suggest appropriate candidates for parathyroidectomy.

“Younger patients (aged < 50 years) may have more aggressive disease,” they explain.

In addition, “patients with serum calcium levels above 3 mmol/L (> 12 mg/dL) are at greater risk for symptomatic hypercalcemia, and patients with a recent history of kidney stones may have fewer future stones after surgical cure.”

“Yet, such patients are a small minority of those with primary hyperparathyroidism,” they note.

The study authors underscore that “our data add evidence to guide the decisionmaking process in deliberative dialogue between clinicians and patients.”

The study received funding from Swedish government grants, the Norwegian Research Council, and the South-Eastern Norway Regional Health Authority.

A version of this article first appeared on Medscape.com.

Patients who receive parathyroidectomy for mild primary hyperparathyroidism show no benefits in survival or morbidity, including fractures, cancer, or cardiovascular outcomes over more than 10 years, compared with those not receiving the surgery, results from a randomized, prospective trial show.

“In contrast to existing data showing increased mortality and cardiovascular morbidity in mild primary hyperparathyroidism, we did not find any treatment effect of parathyroidectomy on these important clinical endpoints,” report the authors of the study, published in the Annals of Internal Medicine.
 

Reason to evaluate and revise current recommendations?

With mild primary hyperparathyroidism becoming the predominant form of hyperparathyroidism, the results suggest rethinking the current recommendations for the condition, the study authors note. 

“Over the years, more active management of mild primary hyperparathyroidism has been recommended, with a widening of criteria for parathyroidectomy,” they write.

“With the low number of kidney stones (n = 5) and no effect of parathyroidectomy on fractures, there may be a need to evaluate and potentially revise the current recommendations.”

The authors of an accompanying editorial agree that “the [results] provide a strong rationale for nonoperative management of patients with mild primary hyperparathyroidism.”

“The findings suggest that most patients can be managed nonoperatively, with monitoring of serum calcium levels every 1 to 2 years or if symptoms occur,” write the editorial authors, Mark J. Bolland, PhD, and Andrew Grey, MD, of the department of medicine, University of Auckland, New Zealand.

Although parathyroidectomy is recommended for the treatment in patients with hyperparathyroidism with severe hypercalcemia or overt symptoms, there has been debate on the long-term benefits of surgery among those with milder cases.  

Most previous studies that have shown benefits, such as reductions in the risk of fracture with parathyroidectomy, have importantly not distinguished between mild and more severe primary hyperparathyroidism, the authors note.
 

No significant differences in mortality between surgery, nonsurgery groups

For the Scandinavian Investigation of Primary Hyperparathyroidism (SIPH) trial, first author Mikkel Pretorius, MD, Oslo University Hospital and Faculty of Medicine, University of Oslo, and colleagues enrolled 191 patients between 1998 and 2005 in Sweden, Norway, and Denmark, who were aged 50-80 years and had mild primary hyperparathyroidism, defined as serum calcium levels of 10.42-11.22 mg/dL.

Participants were randomized to receive surgery (n = 95) or nonoperative observation without intervention (n = 96).

After a 10-year follow-up, 129 patients had completed the final visit. The overall death rate was 7.6%, and, with eight deaths in the surgery group and seven in the nonsurgery group, there were no significant differences between groups in terms of mortality (HR, 1.17; P = .76).

During an extended observation period that lasted until 2018, mortality rates increased by 23%, but with a relatively even distribution of 24 deaths in the surgery group and 20 among those with no surgery.

Chronic hypercalcemia related to primary hyperparathyroidism has been debated as being associated with an increased risk of cardiovascular disease or cancer, however, “the absolute numbers for these and the other disease-specific causes of death were nearly identical between groups,” the authors write, with 17 deaths from cardiovascular disease, eight from cancer, and eight from cerebrovascular disease.

In terms of morbidity, including cardiovascular events, cerebrovascular events, cancer, peripheral fractures, and renal stones, there were 101 events overall, with 52 in the parathyroidectomy group and 49 in the nonsurgery group, which again, was not a significant difference.

Sixteen vertebral fractures occurred overall in 14 patients, which were evenly split at seven patients in each group.

The authors note that “the incidence of peripheral fractures for women in our study was around 2,900 per 100,000 person-years, in the same range as for 70-year-old women in a study in Gothenburg, Sweden (about 2,600 per 100,000 person-years).”

There were no between-group differences in terms of time to death or first morbidity event for any of the prespecified events.

Of the 96 patients originally assigned to the nonsurgery group, 17 (18%) had surgery during follow-up, including three for serious hypercalcemia, three by their own choice, two for decreasing bone density, one for kidney stones, and the others for unclear or unrelated reasons.

Study limitations include that only 26 men (13 in each group) were included, and only 16 completed the study. “The external validity for men based on this study is therefore limited,” the authors note.

And although most people with primary hyperparathyroidism are adults, the older age of participants suggests the results should not be generalized to younger patients with benign parathyroid tumors.

The editorialists note that age should be one of the few factors that may, indeed, suggest appropriate candidates for parathyroidectomy.

“Younger patients (aged < 50 years) may have more aggressive disease,” they explain.

In addition, “patients with serum calcium levels above 3 mmol/L (> 12 mg/dL) are at greater risk for symptomatic hypercalcemia, and patients with a recent history of kidney stones may have fewer future stones after surgical cure.”

“Yet, such patients are a small minority of those with primary hyperparathyroidism,” they note.

The study authors underscore that “our data add evidence to guide the decisionmaking process in deliberative dialogue between clinicians and patients.”

The study received funding from Swedish government grants, the Norwegian Research Council, and the South-Eastern Norway Regional Health Authority.

A version of this article first appeared on Medscape.com.

Patients who receive parathyroidectomy for mild primary hyperparathyroidism show no benefits in survival or morbidity, including fractures, cancer, or cardiovascular outcomes over more than 10 years, compared with those not receiving the surgery, results from a randomized, prospective trial show.

“In contrast to existing data showing increased mortality and cardiovascular morbidity in mild primary hyperparathyroidism, we did not find any treatment effect of parathyroidectomy on these important clinical endpoints,” report the authors of the study, published in the Annals of Internal Medicine.
 

Reason to evaluate and revise current recommendations?

With mild primary hyperparathyroidism becoming the predominant form of hyperparathyroidism, the results suggest rethinking the current recommendations for the condition, the study authors note. 

“Over the years, more active management of mild primary hyperparathyroidism has been recommended, with a widening of criteria for parathyroidectomy,” they write.

“With the low number of kidney stones (n = 5) and no effect of parathyroidectomy on fractures, there may be a need to evaluate and potentially revise the current recommendations.”

The authors of an accompanying editorial agree that “the [results] provide a strong rationale for nonoperative management of patients with mild primary hyperparathyroidism.”

“The findings suggest that most patients can be managed nonoperatively, with monitoring of serum calcium levels every 1 to 2 years or if symptoms occur,” write the editorial authors, Mark J. Bolland, PhD, and Andrew Grey, MD, of the department of medicine, University of Auckland, New Zealand.

Although parathyroidectomy is recommended for the treatment in patients with hyperparathyroidism with severe hypercalcemia or overt symptoms, there has been debate on the long-term benefits of surgery among those with milder cases.  

Most previous studies that have shown benefits, such as reductions in the risk of fracture with parathyroidectomy, have importantly not distinguished between mild and more severe primary hyperparathyroidism, the authors note.
 

No significant differences in mortality between surgery, nonsurgery groups

For the Scandinavian Investigation of Primary Hyperparathyroidism (SIPH) trial, first author Mikkel Pretorius, MD, Oslo University Hospital and Faculty of Medicine, University of Oslo, and colleagues enrolled 191 patients between 1998 and 2005 in Sweden, Norway, and Denmark, who were aged 50-80 years and had mild primary hyperparathyroidism, defined as serum calcium levels of 10.42-11.22 mg/dL.

Participants were randomized to receive surgery (n = 95) or nonoperative observation without intervention (n = 96).

After a 10-year follow-up, 129 patients had completed the final visit. The overall death rate was 7.6%, and, with eight deaths in the surgery group and seven in the nonsurgery group, there were no significant differences between groups in terms of mortality (HR, 1.17; P = .76).

During an extended observation period that lasted until 2018, mortality rates increased by 23%, but with a relatively even distribution of 24 deaths in the surgery group and 20 among those with no surgery.

Chronic hypercalcemia related to primary hyperparathyroidism has been debated as being associated with an increased risk of cardiovascular disease or cancer, however, “the absolute numbers for these and the other disease-specific causes of death were nearly identical between groups,” the authors write, with 17 deaths from cardiovascular disease, eight from cancer, and eight from cerebrovascular disease.

In terms of morbidity, including cardiovascular events, cerebrovascular events, cancer, peripheral fractures, and renal stones, there were 101 events overall, with 52 in the parathyroidectomy group and 49 in the nonsurgery group, which again, was not a significant difference.

Sixteen vertebral fractures occurred overall in 14 patients, which were evenly split at seven patients in each group.

The authors note that “the incidence of peripheral fractures for women in our study was around 2,900 per 100,000 person-years, in the same range as for 70-year-old women in a study in Gothenburg, Sweden (about 2,600 per 100,000 person-years).”

There were no between-group differences in terms of time to death or first morbidity event for any of the prespecified events.

Of the 96 patients originally assigned to the nonsurgery group, 17 (18%) had surgery during follow-up, including three for serious hypercalcemia, three by their own choice, two for decreasing bone density, one for kidney stones, and the others for unclear or unrelated reasons.

Study limitations include that only 26 men (13 in each group) were included, and only 16 completed the study. “The external validity for men based on this study is therefore limited,” the authors note.

And although most people with primary hyperparathyroidism are adults, the older age of participants suggests the results should not be generalized to younger patients with benign parathyroid tumors.

The editorialists note that age should be one of the few factors that may, indeed, suggest appropriate candidates for parathyroidectomy.

“Younger patients (aged < 50 years) may have more aggressive disease,” they explain.

In addition, “patients with serum calcium levels above 3 mmol/L (> 12 mg/dL) are at greater risk for symptomatic hypercalcemia, and patients with a recent history of kidney stones may have fewer future stones after surgical cure.”

“Yet, such patients are a small minority of those with primary hyperparathyroidism,” they note.

The study authors underscore that “our data add evidence to guide the decisionmaking process in deliberative dialogue between clinicians and patients.”

The study received funding from Swedish government grants, the Norwegian Research Council, and the South-Eastern Norway Regional Health Authority.

A version of this article first appeared on Medscape.com.

Key takeaways

Metformin may be associated with a lower risk of neurodegenerative disease, in particular when the drug has been prescribed for at least 4 years, according to a systematic review and meta-analysis of longitudinal data.

However, the heterogeneity between the available studies and the potential heterogeneity of diagnostic criteria may mean that validation studies are needed.
 

Why is this important?

Data suggest that metformin, the most commonly prescribed antidiabetic drug, may be neuroprotective, while diabetes is associated with an excess risk of neurodegenerative disease. Results of studies conducted specifically to investigate the benefit of the antidiabetic drug on cognitive prognosis have been unclear. A meta-analysis was published in 2020, but it included cross-sectional and case-control studies. Given the long observation period needed to measure such an outcome, only cohort studies conducted over several years can provide reliable results. This new meta-analysis attempts to circumvent this limitation.

Methods

The meta-analysis was conducted using studies published up to March 2021 that met the inclusion criteria (population-based cohort studies published in English in which the administration of metformin and associated risk of exposure were reported).

Main results

Twelve studies were included in this analysis, of which eight were retrospective and 11 were considered to be of good methodologic quality. In total, 194,792 patients were included.

Pooled data showed that the relative risk associated with onset of neurodegenerative disease was 0.77 (95% CI, 0.67-0.88) for patients with diabetes taking metformin versus those not taking metformin. However, heterogeneity between studies was high (I2; 78.8%; P < .001).

The effect was greater with longer metformin use, with an RR of 0.29 (95% CI, 0.13-0.44) for those who took metformin for 4 years or more. Similarly, the studies conducted in Asian countries versus other locations suggested an added benefit for this population (RR, 0.69; 95% CI, 0.64-0.74).

Sensitivity analyses confirmed these results, and subtype analyses showed no difference according to the nature of the neurodegenerative disease.

A version of this article first appeared on Univadis.

Key takeaways

Metformin may be associated with a lower risk of neurodegenerative disease, in particular when the drug has been prescribed for at least 4 years, according to a systematic review and meta-analysis of longitudinal data.

However, the heterogeneity between the available studies and the potential heterogeneity of diagnostic criteria may mean that validation studies are needed.
 

Why is this important?

Data suggest that metformin, the most commonly prescribed antidiabetic drug, may be neuroprotective, while diabetes is associated with an excess risk of neurodegenerative disease. Results of studies conducted specifically to investigate the benefit of the antidiabetic drug on cognitive prognosis have been unclear. A meta-analysis was published in 2020, but it included cross-sectional and case-control studies. Given the long observation period needed to measure such an outcome, only cohort studies conducted over several years can provide reliable results. This new meta-analysis attempts to circumvent this limitation.

Methods

The meta-analysis was conducted using studies published up to March 2021 that met the inclusion criteria (population-based cohort studies published in English in which the administration of metformin and associated risk of exposure were reported).

Main results

Twelve studies were included in this analysis, of which eight were retrospective and 11 were considered to be of good methodologic quality. In total, 194,792 patients were included.

Pooled data showed that the relative risk associated with onset of neurodegenerative disease was 0.77 (95% CI, 0.67-0.88) for patients with diabetes taking metformin versus those not taking metformin. However, heterogeneity between studies was high (I2; 78.8%; P < .001).

The effect was greater with longer metformin use, with an RR of 0.29 (95% CI, 0.13-0.44) for those who took metformin for 4 years or more. Similarly, the studies conducted in Asian countries versus other locations suggested an added benefit for this population (RR, 0.69; 95% CI, 0.64-0.74).

Sensitivity analyses confirmed these results, and subtype analyses showed no difference according to the nature of the neurodegenerative disease.

A version of this article first appeared on Univadis.

Key takeaways

Metformin may be associated with a lower risk of neurodegenerative disease, in particular when the drug has been prescribed for at least 4 years, according to a systematic review and meta-analysis of longitudinal data.

However, the heterogeneity between the available studies and the potential heterogeneity of diagnostic criteria may mean that validation studies are needed.
 

Why is this important?

Data suggest that metformin, the most commonly prescribed antidiabetic drug, may be neuroprotective, while diabetes is associated with an excess risk of neurodegenerative disease. Results of studies conducted specifically to investigate the benefit of the antidiabetic drug on cognitive prognosis have been unclear. A meta-analysis was published in 2020, but it included cross-sectional and case-control studies. Given the long observation period needed to measure such an outcome, only cohort studies conducted over several years can provide reliable results. This new meta-analysis attempts to circumvent this limitation.

Methods

The meta-analysis was conducted using studies published up to March 2021 that met the inclusion criteria (population-based cohort studies published in English in which the administration of metformin and associated risk of exposure were reported).

Main results

Twelve studies were included in this analysis, of which eight were retrospective and 11 were considered to be of good methodologic quality. In total, 194,792 patients were included.

Pooled data showed that the relative risk associated with onset of neurodegenerative disease was 0.77 (95% CI, 0.67-0.88) for patients with diabetes taking metformin versus those not taking metformin. However, heterogeneity between studies was high (I2; 78.8%; P < .001).

The effect was greater with longer metformin use, with an RR of 0.29 (95% CI, 0.13-0.44) for those who took metformin for 4 years or more. Similarly, the studies conducted in Asian countries versus other locations suggested an added benefit for this population (RR, 0.69; 95% CI, 0.64-0.74).

Sensitivity analyses confirmed these results, and subtype analyses showed no difference according to the nature of the neurodegenerative disease.

A version of this article first appeared on Univadis.

A scientific analysis of metabolites from plant-based-diets – especially those rich in whole grains, fruits, and vegetables – may in the future yield clues as to how such eating patterns lower the risk of type 2 diabetes, finds a new study of more than 8,000 people.

The research looked at healthy, unhealthy, and overall plant-based diets, but only metabolic profiles for the healthy and overall plant-based diets showed an inverse relationship with type 2 diabetes.

Lisovskaya/iStock/Getty Images Plus

A primarily “unhealthy” plant-based diet was one including mainly refined grains (e.g., white bread and pasta), fruit juices, potatoes, sugar-sweetened beverages, and sweets/desserts.

“Individual metabolites from consumption of polyphenol-rich plant foods like fruits, vegetables, coffee, and legumes are all closely linked to healthy plant-based diet and lower risk of diabetes,” lead author Frank Hu, MD, said in a press release.

Dr. Hu, of the department of nutrition at Harvard T.H. Chan School of Public Health, Boston, and colleagues reported their findings in Diabetologia.
 

High-throughput profiling of the metabolome

Given that an individual’s metabolic profile reflects their diet, there is a growing trend in nutritional research to use a technique called high-throughput metabolomics to profile biological samples.

The team conducted an analysis of blood plasma samples and dietary intake using food frequency questionnaires of 10,684 participants from three prospective cohorts (Nurses’ Health Study, Nurses’ Health Study II, and Health Professionals Follow-Up Study). Participants were predominantly White and middle-aged (mean age 54 years), with a mean body mass index of 25.6 kg/m².

Metabolite profile scores were generated from the blood samples, taken in the 1980s and 1990s, and matched to any cases of incident type 2 diabetes reported during follow-up, which ended in 2016-2017.

The team looked at three different plant-based diets – by definition, higher in plant foods and lower in animal foods – and further categorized them according to the actual foods consumed, to generate an overall plant diet index (PDI), a healthy PDI, or an unhealthy PDI.

In all, 8,827 participants completed the study, and 270 cases of diabetes were reported.

Multi-metabolite profiles were composed of 55 metabolites for the overall PDI, 93 metabolites for healthy PDI, and 75 metabolites for unhealthy PDI.

The findings are that metabolomics can be harnessed and “the identified metabolic profiles could be used to assess adherence to ... plant-based diets as part of type 2 diabetes prevention ... and provide new insights for future investigation,” the researchers concluded.

One coauthor received research support from the California Walnut Commission and Swiss ReManagement; another reported being a scientific consultant to LayerIV. The other authors have reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

A scientific analysis of metabolites from plant-based-diets – especially those rich in whole grains, fruits, and vegetables – may in the future yield clues as to how such eating patterns lower the risk of type 2 diabetes, finds a new study of more than 8,000 people.

The research looked at healthy, unhealthy, and overall plant-based diets, but only metabolic profiles for the healthy and overall plant-based diets showed an inverse relationship with type 2 diabetes.

Lisovskaya/iStock/Getty Images Plus

A primarily “unhealthy” plant-based diet was one including mainly refined grains (e.g., white bread and pasta), fruit juices, potatoes, sugar-sweetened beverages, and sweets/desserts.

“Individual metabolites from consumption of polyphenol-rich plant foods like fruits, vegetables, coffee, and legumes are all closely linked to healthy plant-based diet and lower risk of diabetes,” lead author Frank Hu, MD, said in a press release.

Dr. Hu, of the department of nutrition at Harvard T.H. Chan School of Public Health, Boston, and colleagues reported their findings in Diabetologia.
 

High-throughput profiling of the metabolome

Given that an individual’s metabolic profile reflects their diet, there is a growing trend in nutritional research to use a technique called high-throughput metabolomics to profile biological samples.

The team conducted an analysis of blood plasma samples and dietary intake using food frequency questionnaires of 10,684 participants from three prospective cohorts (Nurses’ Health Study, Nurses’ Health Study II, and Health Professionals Follow-Up Study). Participants were predominantly White and middle-aged (mean age 54 years), with a mean body mass index of 25.6 kg/m².

Metabolite profile scores were generated from the blood samples, taken in the 1980s and 1990s, and matched to any cases of incident type 2 diabetes reported during follow-up, which ended in 2016-2017.

The team looked at three different plant-based diets – by definition, higher in plant foods and lower in animal foods – and further categorized them according to the actual foods consumed, to generate an overall plant diet index (PDI), a healthy PDI, or an unhealthy PDI.

In all, 8,827 participants completed the study, and 270 cases of diabetes were reported.

Multi-metabolite profiles were composed of 55 metabolites for the overall PDI, 93 metabolites for healthy PDI, and 75 metabolites for unhealthy PDI.

The findings are that metabolomics can be harnessed and “the identified metabolic profiles could be used to assess adherence to ... plant-based diets as part of type 2 diabetes prevention ... and provide new insights for future investigation,” the researchers concluded.

One coauthor received research support from the California Walnut Commission and Swiss ReManagement; another reported being a scientific consultant to LayerIV. The other authors have reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

A scientific analysis of metabolites from plant-based-diets – especially those rich in whole grains, fruits, and vegetables – may in the future yield clues as to how such eating patterns lower the risk of type 2 diabetes, finds a new study of more than 8,000 people.

The research looked at healthy, unhealthy, and overall plant-based diets, but only metabolic profiles for the healthy and overall plant-based diets showed an inverse relationship with type 2 diabetes.

Lisovskaya/iStock/Getty Images Plus

A primarily “unhealthy” plant-based diet was one including mainly refined grains (e.g., white bread and pasta), fruit juices, potatoes, sugar-sweetened beverages, and sweets/desserts.

“Individual metabolites from consumption of polyphenol-rich plant foods like fruits, vegetables, coffee, and legumes are all closely linked to healthy plant-based diet and lower risk of diabetes,” lead author Frank Hu, MD, said in a press release.

Dr. Hu, of the department of nutrition at Harvard T.H. Chan School of Public Health, Boston, and colleagues reported their findings in Diabetologia.
 

High-throughput profiling of the metabolome

Given that an individual’s metabolic profile reflects their diet, there is a growing trend in nutritional research to use a technique called high-throughput metabolomics to profile biological samples.

The team conducted an analysis of blood plasma samples and dietary intake using food frequency questionnaires of 10,684 participants from three prospective cohorts (Nurses’ Health Study, Nurses’ Health Study II, and Health Professionals Follow-Up Study). Participants were predominantly White and middle-aged (mean age 54 years), with a mean body mass index of 25.6 kg/m².

Metabolite profile scores were generated from the blood samples, taken in the 1980s and 1990s, and matched to any cases of incident type 2 diabetes reported during follow-up, which ended in 2016-2017.

The team looked at three different plant-based diets – by definition, higher in plant foods and lower in animal foods – and further categorized them according to the actual foods consumed, to generate an overall plant diet index (PDI), a healthy PDI, or an unhealthy PDI.

In all, 8,827 participants completed the study, and 270 cases of diabetes were reported.

Multi-metabolite profiles were composed of 55 metabolites for the overall PDI, 93 metabolites for healthy PDI, and 75 metabolites for unhealthy PDI.

The findings are that metabolomics can be harnessed and “the identified metabolic profiles could be used to assess adherence to ... plant-based diets as part of type 2 diabetes prevention ... and provide new insights for future investigation,” the researchers concluded.

One coauthor received research support from the California Walnut Commission and Swiss ReManagement; another reported being a scientific consultant to LayerIV. The other authors have reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

In the presentation of secondary amenorrhea, pregnancy is the No. 1 differential diagnosis. Once this has been excluded, an algorithm is initiated to determine the etiology, including an assessment of the hypothalamic-pituitary-ovarian axis. While the early onset of ovarian failure can be physically and psychologically disrupting, the effect on fertility is an especially devastating event. Previously identified by terms including premature ovarian failure and premature menopause, “primary ovarian insufficiency” (POI) is now the preferred designation. This month’s article will address the diagnosis, evaluation, and management of POI.

The definition of POI is the development of primary hypogonadism before the age of 40 years. Spontaneous POI occurs in approximately 1 in 250 women by age 35 years and 1 in 100 by age 40 years. After excluding pregnancy, the clinician should determine signs and symptoms that can lead to expedited and cost-efficient testing.

Consequences

POI is an important risk factor for bone loss and osteoporosis, especially in young women who develop ovarian dysfunction before they achieve peak adult bone mass. At the time of diagnosis of POI, a bone density test (dual-energy x-ray absorptiometry) should be obtained. Women with POI may also develop depression and anxiety as well as experience an increased risk for cardiovascular morbidity and mortality, possibly related to endothelial dysfunction.

Young women with spontaneous POI are at increased risk of developing autoimmune adrenal insufficiency (AAI), a potentially fatal disorder. Consequently, to diagnose AAI, serum adrenal cortical and 21-hydroxylase antibodies should be measured in all women who have a karyotype of 46,XX and experience spontaneous POI. Women with AAI have a 50% risk of developing adrenal insufficiency. Despite initial normal adrenal function, women with positive adrenal cortical antibodies should be followed annually.
 

Causes (see table for a more complete list)

Iatrogenic

Known causes of POI include chemotherapy/radiation often in the setting of cancer treatment. The three most commonly used drugs, cyclophosphamide, cisplatin, and doxorubicin, cause POI by inducing death and/or accelerated activation of primordial follicles and increased atresia of growing follicles. The most damaging agents are alkylating drugs. A cyclophosphamide equivalent dose calculator has been established for ovarian failure risk stratification from chemotherapy based on the cumulative dose of alkylating agents received.

One study estimated the radiosensitivity of the oocyte to be less than 2 Gy. Based upon this estimate, the authors calculated the dose of radiotherapy that would result in immediate and permanent ovarian failure in 97.5% of patients as follows:

• 20.3 Gy at birth
• 18.4 Gy at age 10 years
• 16.5 Gy at age 20 years
• 14.3 Gy at age 30 years

Genetic

Approximately 10% of cases are familial. A family history of POI raises concern for a fragile X premutation. Fragile X syndrome is an X-linked form of intellectual disability that is one of the most common causes of mental retardation worldwide. There is a strong relationship between age at menopause, including POI, and premutations for fragile X syndrome. The American College of Obstetricians and Gynecologists recommends that women with POI or an elevated follicle-stimulating hormone (FSH) level before age 40 years without known cause be screened for FMR1 premutations. Approximately 6% of cases of POI are associated with premutations in the FMR1 gene.

Turner syndrome is one of the most common causes of POI and results from the lack of a second X chromosome. The most common chromosomal defect in humans, TS occurs in up to 1.5% of conceptions, 10% of spontaneous abortions, and 1 of 2,500 live births.

Serum antiadrenal and/or anti–21-hydroxylase antibodies and antithyroid antiperoxidase antibodies, can aid in the diagnosis of adrenal gland, ovary, and thyroid autoimmune causes, which is found in 4% of women with spontaneous POI. Testing for the presence of 21-hydroxylase autoantibodies or adrenal autoantibodies is sufficient to make the diagnosis of autoimmune oophoritis in women with proven spontaneous POI.

The etiology of POI remains unknown in approximately 75%-90% of cases. However, studies using whole exome or whole genome sequencing have identified genetic variants in approximately 30%-35% of these patients.
 

Risk factors

Factors that are thought to play a role in determining the age of menopause, include genetics (e.g., FMR1 premutation and mosaic Turner syndrome), ethnicity (earlier among Hispanic women and later in Japanese American women when compared with White women), and smoking (reduced by approximately 2 years ).

Regarding ovarian aging, the holy grail of the reproductive life span is to predict menopause. While the definitive age eludes us, anti-Müllerian hormone levels appear to show promise. An ultrasensitive anti-Müllerian hormone assay (< 0.01 ng/mL) predicted a 79% probability of menopause within 12 months for women aged 51 and above; the probability was 51% for women below age 48.
 

Diagnosis

The three P’s of secondary amenorrhea are physiological, pharmacological, or pathological and can guide the clinician to a targeted evaluation. Physiological causes are pregnancy, the first 6 months of continuous breastfeeding (from elevated prolactin), and natural menopause. Pharmacological etiologies, excluding hormonal treatment that suppresses ovulation (combined oral contraceptives, gonadotropin-releasing hormone agonist/antagonist, or danazol), include agents that inhibit dopamine thereby increasing serum prolactin, such as metoclopramide; phenothiazine antipsychotics, such as haloperidol; and tardive dystonia dopamine-depleting medications, such as reserpine. Pathological causes include pituitary adenomas, thyroid disease, functional hypothalamic amenorrhea from changes in weight, exercise regimen, and stress.

Management

About 50%-75% of women with 46,XX spontaneous POI experience intermittent ovarian function and 5%-10% of women remain able to conceive. Anecdotally, a 32-year-old woman presented to me with primary infertility, secondary amenorrhea, and suspected POI based on vasomotor symptoms and elevated FSH levels. Pelvic ultrasound showed a hemorrhagic cyst, suspicious for a corpus luteum. Two weeks thereafter she reported a positive home urine human chorionic gonadotropin test and ultimately delivered twins. Her diagnosis of POI with amenorrhea remained postpartum.

Unless there is an absolute contraindication, estrogen therapy should be prescribed to women with POI to reduce the risk of osteoporosis, cardiovascular disease, and urogenital atrophy as well as to maintain sexual health and quality of life. For those with an intact uterus, women should receive progesterone because of the risk of endometrial hyperplasia from unopposed estrogen. Rather than oral estrogen, the use of transdermal or vaginal delivery of estrogen is a more physiological approach and provides lower risks of venous thromboembolism and gallbladder disease. Of note, standard postmenopausal hormone therapy, which has a much lower dose of estrogen than combined estrogen-progestin contraceptives, does not provide effective contraception. Per ACOG, systemic hormone treatment should be prescribed until age 50-51 years to all women with POI.

For fertility, women with spontaneous POI can be offered oocyte or embryo donation. The uterus does not age reproductively, unlike oocytes, therefore women can achieve reasonable pregnancy success rates through egg donation despite experiencing menopause.
 

Future potential options

Female germline stem cells have been isolated from neonatal mice and transplanted into sterile adult mice, who then were able to produce offspring. In a second study, oogonial stem cells were isolated from neonatal and adult mouse ovaries; pups were subsequently born from the oocytes. Further experiments are needed before the implications for humans can be determined.

Emotionally traumatic for most women, POI disrupts life plans, hopes, and dreams of raising a family. The approach to the patient with POI involves the above evidence-based testing along with empathy from the health care provider.

Dr. Trolice is director of The IVF Center in Winter Park, Fla., and professor of obstetrics and gynecology at the University of Central Florida, Orlando.

In the presentation of secondary amenorrhea, pregnancy is the No. 1 differential diagnosis. Once this has been excluded, an algorithm is initiated to determine the etiology, including an assessment of the hypothalamic-pituitary-ovarian axis. While the early onset of ovarian failure can be physically and psychologically disrupting, the effect on fertility is an especially devastating event. Previously identified by terms including premature ovarian failure and premature menopause, “primary ovarian insufficiency” (POI) is now the preferred designation. This month’s article will address the diagnosis, evaluation, and management of POI.

The definition of POI is the development of primary hypogonadism before the age of 40 years. Spontaneous POI occurs in approximately 1 in 250 women by age 35 years and 1 in 100 by age 40 years. After excluding pregnancy, the clinician should determine signs and symptoms that can lead to expedited and cost-efficient testing.

Consequences

POI is an important risk factor for bone loss and osteoporosis, especially in young women who develop ovarian dysfunction before they achieve peak adult bone mass. At the time of diagnosis of POI, a bone density test (dual-energy x-ray absorptiometry) should be obtained. Women with POI may also develop depression and anxiety as well as experience an increased risk for cardiovascular morbidity and mortality, possibly related to endothelial dysfunction.

Young women with spontaneous POI are at increased risk of developing autoimmune adrenal insufficiency (AAI), a potentially fatal disorder. Consequently, to diagnose AAI, serum adrenal cortical and 21-hydroxylase antibodies should be measured in all women who have a karyotype of 46,XX and experience spontaneous POI. Women with AAI have a 50% risk of developing adrenal insufficiency. Despite initial normal adrenal function, women with positive adrenal cortical antibodies should be followed annually.
 

Causes (see table for a more complete list)

Iatrogenic

Known causes of POI include chemotherapy/radiation often in the setting of cancer treatment. The three most commonly used drugs, cyclophosphamide, cisplatin, and doxorubicin, cause POI by inducing death and/or accelerated activation of primordial follicles and increased atresia of growing follicles. The most damaging agents are alkylating drugs. A cyclophosphamide equivalent dose calculator has been established for ovarian failure risk stratification from chemotherapy based on the cumulative dose of alkylating agents received.

One study estimated the radiosensitivity of the oocyte to be less than 2 Gy. Based upon this estimate, the authors calculated the dose of radiotherapy that would result in immediate and permanent ovarian failure in 97.5% of patients as follows:

• 20.3 Gy at birth
• 18.4 Gy at age 10 years
• 16.5 Gy at age 20 years
• 14.3 Gy at age 30 years

Genetic

Approximately 10% of cases are familial. A family history of POI raises concern for a fragile X premutation. Fragile X syndrome is an X-linked form of intellectual disability that is one of the most common causes of mental retardation worldwide. There is a strong relationship between age at menopause, including POI, and premutations for fragile X syndrome. The American College of Obstetricians and Gynecologists recommends that women with POI or an elevated follicle-stimulating hormone (FSH) level before age 40 years without known cause be screened for FMR1 premutations. Approximately 6% of cases of POI are associated with premutations in the FMR1 gene.

Turner syndrome is one of the most common causes of POI and results from the lack of a second X chromosome. The most common chromosomal defect in humans, TS occurs in up to 1.5% of conceptions, 10% of spontaneous abortions, and 1 of 2,500 live births.

Serum antiadrenal and/or anti–21-hydroxylase antibodies and antithyroid antiperoxidase antibodies, can aid in the diagnosis of adrenal gland, ovary, and thyroid autoimmune causes, which is found in 4% of women with spontaneous POI. Testing for the presence of 21-hydroxylase autoantibodies or adrenal autoantibodies is sufficient to make the diagnosis of autoimmune oophoritis in women with proven spontaneous POI.

The etiology of POI remains unknown in approximately 75%-90% of cases. However, studies using whole exome or whole genome sequencing have identified genetic variants in approximately 30%-35% of these patients.
 

Risk factors

Factors that are thought to play a role in determining the age of menopause, include genetics (e.g., FMR1 premutation and mosaic Turner syndrome), ethnicity (earlier among Hispanic women and later in Japanese American women when compared with White women), and smoking (reduced by approximately 2 years ).

Regarding ovarian aging, the holy grail of the reproductive life span is to predict menopause. While the definitive age eludes us, anti-Müllerian hormone levels appear to show promise. An ultrasensitive anti-Müllerian hormone assay (< 0.01 ng/mL) predicted a 79% probability of menopause within 12 months for women aged 51 and above; the probability was 51% for women below age 48.
 

Diagnosis

The three P’s of secondary amenorrhea are physiological, pharmacological, or pathological and can guide the clinician to a targeted evaluation. Physiological causes are pregnancy, the first 6 months of continuous breastfeeding (from elevated prolactin), and natural menopause. Pharmacological etiologies, excluding hormonal treatment that suppresses ovulation (combined oral contraceptives, gonadotropin-releasing hormone agonist/antagonist, or danazol), include agents that inhibit dopamine thereby increasing serum prolactin, such as metoclopramide; phenothiazine antipsychotics, such as haloperidol; and tardive dystonia dopamine-depleting medications, such as reserpine. Pathological causes include pituitary adenomas, thyroid disease, functional hypothalamic amenorrhea from changes in weight, exercise regimen, and stress.

Management

About 50%-75% of women with 46,XX spontaneous POI experience intermittent ovarian function and 5%-10% of women remain able to conceive. Anecdotally, a 32-year-old woman presented to me with primary infertility, secondary amenorrhea, and suspected POI based on vasomotor symptoms and elevated FSH levels. Pelvic ultrasound showed a hemorrhagic cyst, suspicious for a corpus luteum. Two weeks thereafter she reported a positive home urine human chorionic gonadotropin test and ultimately delivered twins. Her diagnosis of POI with amenorrhea remained postpartum.

Unless there is an absolute contraindication, estrogen therapy should be prescribed to women with POI to reduce the risk of osteoporosis, cardiovascular disease, and urogenital atrophy as well as to maintain sexual health and quality of life. For those with an intact uterus, women should receive progesterone because of the risk of endometrial hyperplasia from unopposed estrogen. Rather than oral estrogen, the use of transdermal or vaginal delivery of estrogen is a more physiological approach and provides lower risks of venous thromboembolism and gallbladder disease. Of note, standard postmenopausal hormone therapy, which has a much lower dose of estrogen than combined estrogen-progestin contraceptives, does not provide effective contraception. Per ACOG, systemic hormone treatment should be prescribed until age 50-51 years to all women with POI.

For fertility, women with spontaneous POI can be offered oocyte or embryo donation. The uterus does not age reproductively, unlike oocytes, therefore women can achieve reasonable pregnancy success rates through egg donation despite experiencing menopause.
 

Future potential options

Female germline stem cells have been isolated from neonatal mice and transplanted into sterile adult mice, who then were able to produce offspring. In a second study, oogonial stem cells were isolated from neonatal and adult mouse ovaries; pups were subsequently born from the oocytes. Further experiments are needed before the implications for humans can be determined.

Emotionally traumatic for most women, POI disrupts life plans, hopes, and dreams of raising a family. The approach to the patient with POI involves the above evidence-based testing along with empathy from the health care provider.

Dr. Trolice is director of The IVF Center in Winter Park, Fla., and professor of obstetrics and gynecology at the University of Central Florida, Orlando.

In the presentation of secondary amenorrhea, pregnancy is the No. 1 differential diagnosis. Once this has been excluded, an algorithm is initiated to determine the etiology, including an assessment of the hypothalamic-pituitary-ovarian axis. While the early onset of ovarian failure can be physically and psychologically disrupting, the effect on fertility is an especially devastating event. Previously identified by terms including premature ovarian failure and premature menopause, “primary ovarian insufficiency” (POI) is now the preferred designation. This month’s article will address the diagnosis, evaluation, and management of POI.

The definition of POI is the development of primary hypogonadism before the age of 40 years. Spontaneous POI occurs in approximately 1 in 250 women by age 35 years and 1 in 100 by age 40 years. After excluding pregnancy, the clinician should determine signs and symptoms that can lead to expedited and cost-efficient testing.

Consequences

POI is an important risk factor for bone loss and osteoporosis, especially in young women who develop ovarian dysfunction before they achieve peak adult bone mass. At the time of diagnosis of POI, a bone density test (dual-energy x-ray absorptiometry) should be obtained. Women with POI may also develop depression and anxiety as well as experience an increased risk for cardiovascular morbidity and mortality, possibly related to endothelial dysfunction.

Young women with spontaneous POI are at increased risk of developing autoimmune adrenal insufficiency (AAI), a potentially fatal disorder. Consequently, to diagnose AAI, serum adrenal cortical and 21-hydroxylase antibodies should be measured in all women who have a karyotype of 46,XX and experience spontaneous POI. Women with AAI have a 50% risk of developing adrenal insufficiency. Despite initial normal adrenal function, women with positive adrenal cortical antibodies should be followed annually.
 

Causes (see table for a more complete list)

Iatrogenic

Known causes of POI include chemotherapy/radiation often in the setting of cancer treatment. The three most commonly used drugs, cyclophosphamide, cisplatin, and doxorubicin, cause POI by inducing death and/or accelerated activation of primordial follicles and increased atresia of growing follicles. The most damaging agents are alkylating drugs. A cyclophosphamide equivalent dose calculator has been established for ovarian failure risk stratification from chemotherapy based on the cumulative dose of alkylating agents received.

One study estimated the radiosensitivity of the oocyte to be less than 2 Gy. Based upon this estimate, the authors calculated the dose of radiotherapy that would result in immediate and permanent ovarian failure in 97.5% of patients as follows:

• 20.3 Gy at birth
• 18.4 Gy at age 10 years
• 16.5 Gy at age 20 years
• 14.3 Gy at age 30 years

Genetic

Approximately 10% of cases are familial. A family history of POI raises concern for a fragile X premutation. Fragile X syndrome is an X-linked form of intellectual disability that is one of the most common causes of mental retardation worldwide. There is a strong relationship between age at menopause, including POI, and premutations for fragile X syndrome. The American College of Obstetricians and Gynecologists recommends that women with POI or an elevated follicle-stimulating hormone (FSH) level before age 40 years without known cause be screened for FMR1 premutations. Approximately 6% of cases of POI are associated with premutations in the FMR1 gene.

Turner syndrome is one of the most common causes of POI and results from the lack of a second X chromosome. The most common chromosomal defect in humans, TS occurs in up to 1.5% of conceptions, 10% of spontaneous abortions, and 1 of 2,500 live births.

Serum antiadrenal and/or anti–21-hydroxylase antibodies and antithyroid antiperoxidase antibodies, can aid in the diagnosis of adrenal gland, ovary, and thyroid autoimmune causes, which is found in 4% of women with spontaneous POI. Testing for the presence of 21-hydroxylase autoantibodies or adrenal autoantibodies is sufficient to make the diagnosis of autoimmune oophoritis in women with proven spontaneous POI.

The etiology of POI remains unknown in approximately 75%-90% of cases. However, studies using whole exome or whole genome sequencing have identified genetic variants in approximately 30%-35% of these patients.
 

Risk factors

Factors that are thought to play a role in determining the age of menopause, include genetics (e.g., FMR1 premutation and mosaic Turner syndrome), ethnicity (earlier among Hispanic women and later in Japanese American women when compared with White women), and smoking (reduced by approximately 2 years ).

Regarding ovarian aging, the holy grail of the reproductive life span is to predict menopause. While the definitive age eludes us, anti-Müllerian hormone levels appear to show promise. An ultrasensitive anti-Müllerian hormone assay (< 0.01 ng/mL) predicted a 79% probability of menopause within 12 months for women aged 51 and above; the probability was 51% for women below age 48.
 

Diagnosis

The three P’s of secondary amenorrhea are physiological, pharmacological, or pathological and can guide the clinician to a targeted evaluation. Physiological causes are pregnancy, the first 6 months of continuous breastfeeding (from elevated prolactin), and natural menopause. Pharmacological etiologies, excluding hormonal treatment that suppresses ovulation (combined oral contraceptives, gonadotropin-releasing hormone agonist/antagonist, or danazol), include agents that inhibit dopamine thereby increasing serum prolactin, such as metoclopramide; phenothiazine antipsychotics, such as haloperidol; and tardive dystonia dopamine-depleting medications, such as reserpine. Pathological causes include pituitary adenomas, thyroid disease, functional hypothalamic amenorrhea from changes in weight, exercise regimen, and stress.

Management

About 50%-75% of women with 46,XX spontaneous POI experience intermittent ovarian function and 5%-10% of women remain able to conceive. Anecdotally, a 32-year-old woman presented to me with primary infertility, secondary amenorrhea, and suspected POI based on vasomotor symptoms and elevated FSH levels. Pelvic ultrasound showed a hemorrhagic cyst, suspicious for a corpus luteum. Two weeks thereafter she reported a positive home urine human chorionic gonadotropin test and ultimately delivered twins. Her diagnosis of POI with amenorrhea remained postpartum.

Unless there is an absolute contraindication, estrogen therapy should be prescribed to women with POI to reduce the risk of osteoporosis, cardiovascular disease, and urogenital atrophy as well as to maintain sexual health and quality of life. For those with an intact uterus, women should receive progesterone because of the risk of endometrial hyperplasia from unopposed estrogen. Rather than oral estrogen, the use of transdermal or vaginal delivery of estrogen is a more physiological approach and provides lower risks of venous thromboembolism and gallbladder disease. Of note, standard postmenopausal hormone therapy, which has a much lower dose of estrogen than combined estrogen-progestin contraceptives, does not provide effective contraception. Per ACOG, systemic hormone treatment should be prescribed until age 50-51 years to all women with POI.

For fertility, women with spontaneous POI can be offered oocyte or embryo donation. The uterus does not age reproductively, unlike oocytes, therefore women can achieve reasonable pregnancy success rates through egg donation despite experiencing menopause.
 

Future potential options

Female germline stem cells have been isolated from neonatal mice and transplanted into sterile adult mice, who then were able to produce offspring. In a second study, oogonial stem cells were isolated from neonatal and adult mouse ovaries; pups were subsequently born from the oocytes. Further experiments are needed before the implications for humans can be determined.

Emotionally traumatic for most women, POI disrupts life plans, hopes, and dreams of raising a family. The approach to the patient with POI involves the above evidence-based testing along with empathy from the health care provider.

Dr. Trolice is director of The IVF Center in Winter Park, Fla., and professor of obstetrics and gynecology at the University of Central Florida, Orlando.

Bone strength and microarchitecture remained stronger at 24 months after treatment with denosumab compared to risedronate, in a study of 110 adults using glucocorticoids.

Patients using glucocorticoids are at increased risk for vertebral and nonvertebral fractures at both the start of treatment or as treatment continues, wrote Piet Geusens, MD, of Maastricht University, the Netherlands, and colleagues.

Imaging data collected via high-resolution peripheral quantitative computed tomography (HR-pQCT) allow for the assessment of bone microarchitecture and strength, but specific data comparing the impact of bone treatment in patients using glucocorticoids are lacking, they said.

In a study published in the Journal of Bone and Mineral Research, the researchers identified a subset of 56 patients randomized to denosumab and 54 to risedronate patients out of a total of 590 patients who were enrolled in a phase 3 randomized, controlled trial of denosumab vs. risedronate for bone mineral density. The main results of the larger trial – presented at EULAR 2018 – showed greater increases in bone strength with denosumab over risedronate in patients receiving glucocorticoids.

In the current study, the researchers reviewed HR-pQCT scans of the distal radius and tibia at baseline, 12 months, and 24 months. Bone strength and microarchitecture were defined in terms of failure load (FL) as a primary outcome. Patients also were divided into subpopulations of those initiating glucocorticoid treatment (GC-I) and continuing treatment (GC-C).

Baseline characteristics were mainly balanced among the treatment groups within the GC-I and GC-C categories.

Among the GC-I patients, in the denosumab group, FL increased significantly from baseline to 12 months at the radius at tibia (1.8% and 1.7%, respectively) but did not change significantly in the risedronate group, which translated to a significant treatment difference between the drugs of 3.3% for radius and 2.5% for tibia.

At 24 months, the radius measure of FL was unchanged from baseline in denosumab patients but significantly decreased in risedronate patients, with a difference of –4.1%, which translated to a significant between-treatment difference at the radius of 5.6% (P < .001). Changes at the tibia were not significantly different between the groups at 24 months.

Among the GC-C patients, FL was unchanged from baseline to 12 months for both the denosumab and risedronate groups. However, FL significantly increased with denosumab (4.3%) and remained unchanged in the risedronate group.

The researchers also found significant differences between denosumab and risedronate in percentage changes in cortical bone mineral density, and less prominent changes and differences in trabecular bone mineral density.

The study findings were limited by several factors including the use of the HR-pQCT scanner, which limits the measurement of trabecular microarchitecture, and the use of only standard HR-pQCT parameters, which do not allow insight into endosteal changes, and the inability to correct for multiplicity of data, the researchers noted.

However, the results support the superiority of denosumab over risedronate for preventing FL and total bone mineral density loss at the radius and tibia in new glucocorticoid users, and for increasing FL and total bone mineral density at the radius in long-term glucocorticoid users, they said.

Denosumab therefore could be a useful therapeutic option and could inform decision-making in patients initiating GC-therapy or on long-term GC-therapy, they concluded.

The study was supported by Amgen. Dr. Geusens disclosed grants from Amgen, Celgene, Lilly, Merck, Pfizer, Roche, UCB, Fresenius, Mylan, and Sandoz, and grants and other funding from AbbVie, outside the current study.

Bone strength and microarchitecture remained stronger at 24 months after treatment with denosumab compared to risedronate, in a study of 110 adults using glucocorticoids.

Patients using glucocorticoids are at increased risk for vertebral and nonvertebral fractures at both the start of treatment or as treatment continues, wrote Piet Geusens, MD, of Maastricht University, the Netherlands, and colleagues.

Imaging data collected via high-resolution peripheral quantitative computed tomography (HR-pQCT) allow for the assessment of bone microarchitecture and strength, but specific data comparing the impact of bone treatment in patients using glucocorticoids are lacking, they said.

In a study published in the Journal of Bone and Mineral Research, the researchers identified a subset of 56 patients randomized to denosumab and 54 to risedronate patients out of a total of 590 patients who were enrolled in a phase 3 randomized, controlled trial of denosumab vs. risedronate for bone mineral density. The main results of the larger trial – presented at EULAR 2018 – showed greater increases in bone strength with denosumab over risedronate in patients receiving glucocorticoids.

In the current study, the researchers reviewed HR-pQCT scans of the distal radius and tibia at baseline, 12 months, and 24 months. Bone strength and microarchitecture were defined in terms of failure load (FL) as a primary outcome. Patients also were divided into subpopulations of those initiating glucocorticoid treatment (GC-I) and continuing treatment (GC-C).

Baseline characteristics were mainly balanced among the treatment groups within the GC-I and GC-C categories.

Among the GC-I patients, in the denosumab group, FL increased significantly from baseline to 12 months at the radius at tibia (1.8% and 1.7%, respectively) but did not change significantly in the risedronate group, which translated to a significant treatment difference between the drugs of 3.3% for radius and 2.5% for tibia.

At 24 months, the radius measure of FL was unchanged from baseline in denosumab patients but significantly decreased in risedronate patients, with a difference of –4.1%, which translated to a significant between-treatment difference at the radius of 5.6% (P < .001). Changes at the tibia were not significantly different between the groups at 24 months.

Among the GC-C patients, FL was unchanged from baseline to 12 months for both the denosumab and risedronate groups. However, FL significantly increased with denosumab (4.3%) and remained unchanged in the risedronate group.

The researchers also found significant differences between denosumab and risedronate in percentage changes in cortical bone mineral density, and less prominent changes and differences in trabecular bone mineral density.

The study findings were limited by several factors including the use of the HR-pQCT scanner, which limits the measurement of trabecular microarchitecture, and the use of only standard HR-pQCT parameters, which do not allow insight into endosteal changes, and the inability to correct for multiplicity of data, the researchers noted.

However, the results support the superiority of denosumab over risedronate for preventing FL and total bone mineral density loss at the radius and tibia in new glucocorticoid users, and for increasing FL and total bone mineral density at the radius in long-term glucocorticoid users, they said.

Denosumab therefore could be a useful therapeutic option and could inform decision-making in patients initiating GC-therapy or on long-term GC-therapy, they concluded.

The study was supported by Amgen. Dr. Geusens disclosed grants from Amgen, Celgene, Lilly, Merck, Pfizer, Roche, UCB, Fresenius, Mylan, and Sandoz, and grants and other funding from AbbVie, outside the current study.

Bone strength and microarchitecture remained stronger at 24 months after treatment with denosumab compared to risedronate, in a study of 110 adults using glucocorticoids.

Patients using glucocorticoids are at increased risk for vertebral and nonvertebral fractures at both the start of treatment or as treatment continues, wrote Piet Geusens, MD, of Maastricht University, the Netherlands, and colleagues.

Imaging data collected via high-resolution peripheral quantitative computed tomography (HR-pQCT) allow for the assessment of bone microarchitecture and strength, but specific data comparing the impact of bone treatment in patients using glucocorticoids are lacking, they said.

In a study published in the Journal of Bone and Mineral Research, the researchers identified a subset of 56 patients randomized to denosumab and 54 to risedronate patients out of a total of 590 patients who were enrolled in a phase 3 randomized, controlled trial of denosumab vs. risedronate for bone mineral density. The main results of the larger trial – presented at EULAR 2018 – showed greater increases in bone strength with denosumab over risedronate in patients receiving glucocorticoids.

In the current study, the researchers reviewed HR-pQCT scans of the distal radius and tibia at baseline, 12 months, and 24 months. Bone strength and microarchitecture were defined in terms of failure load (FL) as a primary outcome. Patients also were divided into subpopulations of those initiating glucocorticoid treatment (GC-I) and continuing treatment (GC-C).

Baseline characteristics were mainly balanced among the treatment groups within the GC-I and GC-C categories.

Among the GC-I patients, in the denosumab group, FL increased significantly from baseline to 12 months at the radius at tibia (1.8% and 1.7%, respectively) but did not change significantly in the risedronate group, which translated to a significant treatment difference between the drugs of 3.3% for radius and 2.5% for tibia.

At 24 months, the radius measure of FL was unchanged from baseline in denosumab patients but significantly decreased in risedronate patients, with a difference of –4.1%, which translated to a significant between-treatment difference at the radius of 5.6% (P < .001). Changes at the tibia were not significantly different between the groups at 24 months.

Among the GC-C patients, FL was unchanged from baseline to 12 months for both the denosumab and risedronate groups. However, FL significantly increased with denosumab (4.3%) and remained unchanged in the risedronate group.

The researchers also found significant differences between denosumab and risedronate in percentage changes in cortical bone mineral density, and less prominent changes and differences in trabecular bone mineral density.

The study findings were limited by several factors including the use of the HR-pQCT scanner, which limits the measurement of trabecular microarchitecture, and the use of only standard HR-pQCT parameters, which do not allow insight into endosteal changes, and the inability to correct for multiplicity of data, the researchers noted.

However, the results support the superiority of denosumab over risedronate for preventing FL and total bone mineral density loss at the radius and tibia in new glucocorticoid users, and for increasing FL and total bone mineral density at the radius in long-term glucocorticoid users, they said.

Denosumab therefore could be a useful therapeutic option and could inform decision-making in patients initiating GC-therapy or on long-term GC-therapy, they concluded.

The study was supported by Amgen. Dr. Geusens disclosed grants from Amgen, Celgene, Lilly, Merck, Pfizer, Roche, UCB, Fresenius, Mylan, and Sandoz, and grants and other funding from AbbVie, outside the current study.

The hormones thyroxine (T4) and triiodothyronine (T3), produced by the thyroid gland, are crucial for maintaining metabolism. A deficit of thyroid hormone production—hypothyroidism—is a common endocrine disorder seen in primary care.

Many patients with hypothyroidism do not achieve optimal treatment goals or see an improvement in their quality of life.

Although the diagnosis and management of hypothyroidism are considered straightforward, many patients with hypothyroidism do not achieve optimal treatment goals or see an improvement in their quality of life. In this article, we address the questionable utility of screening; outline the diagnostic approach, including the central role of laboratory testing; and explain why treatment requires a precise approach to address the range of patient types.

Epidemiology and classification

Estimates are that almost 5% of Americans 12 years or older have hypothyroidism; older people and women are more likely to develop the condition. ¹ In the US National Health and Nutrition Examination Survey (NHANES III) of 13,344 people without known thyroid disease or a family history, hypothyroidism was found in 4.6% (overt [clinical] in 0.3% and subclinical in 4.3%); 11% had a high serum thyroid peroxidase antibody level, which increases their risk of hypothyroidism, and is treated the same as hypothyroidism of other causes; and, overall, lower serum thyroid-stimulating hormone (TSH) levels were seen in Blacks, compared to Whites and Mexican Americans.¹

Copyright Steve and Myriam Oh

Primary hypothyroidism accounts for > 95% of cases of hypothyroidism, representing a failure of the thyroid gland to produce sufficient hormone. It has been shown that, in iodine-replete countries such as the United States, the prevalence of spontaneous hypothyroidism is 1% to 2%, and it is 10 times more common in women.^2,3

Central hypothyroidism is caused by insufficient stimulation of the thyroid gland by TSH, due to pituitary (secondary hypothyroidism) or hypothalamic (tertiary hypothyroidism) disease and is estimated to occur in 1 in every 20,000 to 80,000 people in the general population.⁴

How does hypothyroidism manifest?

Signs and symptoms. Manifestations of hypothyroidism range from life-threatening to minimal or no clinical signs and symptoms (TABLE W1). Signs and symptoms of low thyroid function vary by the degree of hypothyroidism at presentation.

Common signs and symptoms of low thyroid function include fatigue, weight gain, dry skin, brittle hair, hair loss, morning stiffness, muscle aches, joint pain, cold intolerance, diffuse headache, constipation, difficulty concentrating, low libido, depression, and menstrual irregularities. On physical examination, a patient might present with bradycardia, hypotension, hypothermia with slow speech or movement, coarse facial appearance, goiter, diffuse hair loss, cold hands and feet, and a prolonged Achilles tendon reflex.⁵ Skin findings, such as keratosis pilaris, palmoplantar keratoderma (thickening of the skin), and pityriasis rubra pilar, can be associated with autoimmune hypothyroidism.^6,7

Continue to: Carpal tunnel syndrome...

Carpal tunnel syndrome, plantar fasciitis, infertility or miscarriage, dyspepsia, and small intestinal bacterial overgrowth can be associated with hypothyroidism; thyroid function should therefore be assessed in patients who have any of these conditions, along with other signs and symptoms of low thyroid function.^8,9 A patient with severe hypothyroidism might present with hemodynamic instability, pericardial or pleural effusion, and myxedema coma.¹⁰

Clues in the history and from the lab. A history of radiation to the head, neck, or chest area and a history or family history of autoimmune disorders are risk factors for autoimmune thyroid disease.^11,12 Laboratory findings can include markers of oxidative stress, such as elevated levels of low-density lipoprotein cholesterol and serum malondialdehyde.^13-15

Screening and diagnosis

Screening. The US Preventive Services Task Force has asserted that evidence is insufficient by which to evaluate the benefits and risks of routine screening for thyroid dysfunction in nonpregnant, asymptomatic adults.¹⁶ According to the American Thyroid Association and the American Association of Clinical Endocrinologists, screening should be considered in high-risk patients, including those who take medication that affects thyroid function or the results of thyroid hormone assays (TABLE W2, available at mdedge.com/familymedicine).^17-20

Screening inpatients is challenging and usually not recommended unless thyroid disease is strongly suspected. This is because changes in the levels of thyroid hormones, binding proteins, and the TSH concentration can occur in severe nonthyroidal illness; in addition, assay interference by antibodies and other substances can affect thyroid hormone measurement.²¹

Testing strategy. Generally, screening and diagnosis of hypothyroidism are based primarily on laboratory testing, because signs and symptoms are nonspecific (FIGURE 1⁵). A serum TSH level is usually the initial test when screening for thyroid dysfunction. A normal serum TSH value ranges from 0.5-5.0 mIU/L.

A patient with severe hypothyroidism might present with hemodynamic instability, pericardial or pleural effusion, or myxedema coma.

When an abnormal serum TSH level is found, further tests can be performed to investigate, including a serum free thyroxine (FT4) test. (Our preference is to order TSH and FT4 assays simultaneously to facilitate and confirm the diagnosis.) An FT4 test measures the amount of unattached, or free, thyroxine in blood by immunoassay. A normal FT4 value usually ranges from 0.7-1.9 ng/dL.

The combination of a high TSH level and a low FT4 level could be an indication of an underactive thyroid gland (ie, clinical or overt hypothyroidism). Milder, subclinical hypothyroidism is characterized by a ­higher-than-normal TSH level but a normal FT4 level.²² Central (secondary) hypothyroidism is characterized by a low serum FT4 level and a serum TSH level that can be below the reference range, low normal, or even slightly high.⁴

Continue to: These measurements...

These measurements must be interpreted within the context of the laboratory-specific normal range for each test. Third-generation serum TSH assays are more sensitive and specific than serum FT4 measurements for hypothyroidism. FT4 is usually measured by automated analogue immunoassay, which generally provides reliable results; abnormal binding proteins or other interferences occur in some patients, however, resulting in reporting of a falsely high, or falsely low, FT4 level. In such cases, FT4 by direct dialysis, or total T4, can be measured for further evaluation. In primary care, you are most likely to encounter primary hypothyroidism; secondary (central) hypothyroidism is much rarer (< 5% of cases).⁴

The ins and outs of treatment

For most patients, hypothyroidism is a permanent disorder requiring lifelong thyroid hormone replacement therapy—unless the disease is transient (ie, painless or subacute thyroiditis); reversible, because it is caused by medication; or responsive to medical intervention that addresses the underlying autoimmune condition.¹⁹ Goals of treatment (Figure 2^5,23) are to:

• normalize the TSH level to 0.5-5.0 mIU/L (the main goal), with an age-related shift toward a higher TSH goal in older patients (and an upper limit of normal of 7.5 mIU/L in patients who are ≥ 80 years of age)²⁰
• restore the euthyroid state
• relieve symptoms
• reduce any goiter
• avoid overtreatment (iatrogenic thyrotoxicosis).

Desiccated thyroid extract (DTE), developed in the late 1880s and made from the dried thyroid gland of pigs, sheep, or cows, was the earliest treatment for hypothyroidism. The use of DTE has declined since the introduction of synthetic thyroxine (T4, or levothyroxine [here, referred to as LT4]), which is now the standard treatment.^20-22 LT4 is deiodinated in peripheral tissues to form T3, the active thyroid hormone; this process accounts for 80% of total T3 production daily.²⁴

LT4 formulations. LT4 is commercially available in tablet, soft-gel, and liquid preparations. Most patients are treated with the tablet; the soft-gel capsule or liquid is an option for patients who absorb the tablet poorly (because of atrophic gastritis, celiac disease, or gluten sensitivity or because they are post bariatric surgery). Increasing the dosage of the tablet form of LT4, with ongoing TSH monitoring, is more cost effective than moving to an alternative preparation.

If a switch of LT4 formulation is made (ie, from one manufacturer to another), test the serum TSH level to ensure that the therapeutic goal is being reached. Also, in our experience, it is best to prescribe a brand-name preparation of levothyroxine, not a generic, whenever possible, due to the variability in generic formulations and the potential presence of other (inert) ingredients.²⁵

Dosing (TABLE 3^20,23). The average full replacement dosage of LT4 for a young, healthy adult is approximately 1.6 mcg/kg/d. Older patients (> 65 years) or those with coronary artery disease (CAD) should be started on a lower dosage (25-50 mcg/d) and titrated to goal accordingly.

LT4 (tablets, soft-gel capsules, or liquid) should be administered on an empty stomach, with water only, 30 to 60 minutes before breakfast. Medications that interfere with LT4 absorption (eg, bile acid resins, calcium carbonate, ferrous sulfate) should be taken several hours after LT4. For patients who cannot take LT4 in the morning, taking it at bedtime (≥ 2-3 hours after the last meal) is acceptable.

Continue to: Monitoring and titrating

Monitoring and titrating. Hypothyroid symptoms usually improve after 2 or 3 weeks of LT4 treatment; in severe hypothyroidism, complete recovery might take months. Approximately 6 weeks after LT4 therapy is initiated, serum TSH should be measured. After assessing whether administration of LT4 at the starting dosage is appropriate, that dosage can be increased, or decreased, every 4 to 6 weeks until the TSH goal is reached. Once the patient is maintained at a given dosage, measure serum TSH once a year—more often if there is an abnormal result or a change in the patient’s health status.²³

Adverse effects of LT4 therapy are rare, unless over-replacement occurs. Rarely, patients have an allergy to the dye or an excipient (filler) in the tablet.^26-28 The white, 50-mcg tablets can be given safely to patients with dye sensitivity. For those who have an allergy to an excipient (except gelatin) or gluten intolerance, the LT4 soft-gel capsule or liquid preparation (Tirosint) can be prescribed.

Pure LT4, in a capsule made from vegetable sources, can be ordered through a compounding pharmacy for patients who are allergic to animal products.

Anemia, especially iron-deficiency anemia, can cause intolerance to LT4 therapy; in such patients, lowering the starting dosage and treating anemia are indicated.²⁹

Persistent symptoms (despite a normal TSH level). Because many hypothyroid symptoms are nonspecific, patients might come to think that their LT4 dosage is inadequate if they feel tired or gain weight. Persistent hypothyroid symptoms despite a normal serum TSH level might be due to (1) the inability of LT4 therapy to restore tissue thyroid hormone levels to normal or (2) other variables unrelated to hypothyroidism, including disorders associated with inflammation or autoimmune disease, certain medications, diet, lifestyle, and environmental toxins.

These patients might benefit from a detailed history to identify other causes and a switch to either LT4 + liothyronine (LT3; synthetic T3) combination therapy or DTE^26,30-33 (TABLE 4³⁴), although a beneficial effect of LT4 + LT3 therapy was not seen in several studies.^35,36 Over-replacement with LT4 should be discouraged, due to concerns about thyrotoxicosis and its complications (eg, atrial fibrillation, accelerated bone loss).

DTE and LT4 + LT3. Use of DTE has decreased since the 1970s, when LT4 became the therapy of choice. Subsequently, anecdotal evidence emerged that some patients did not feel well on LT4 and preferred to return to DTE.^32,33

Continue to: Several clinical trials...

Several clinical trials addressed the question of whether residual symptoms could be resolved through LT4 + LT3 combination therapy^31-39 (TABLE 4³⁴), but evidence of any consistent superiority of combination therapy was not demonstrated.^35-39 In selected cases, patients might prefer the combination approach.^31,33,39 The quality of life of hypothyroid patients was found to be similarly improved with LT4 or DTE, but the latter was associated with modest weight loss (approximately 4 lbs); nearly 50% of study patients preferred treatment with DTE over LT4.³³ A follow-up study did not confirm weight loss with DTE, however.³⁴

When LT4 monotherapy and LT4 + LT3 combination therapy were compared, results were mixed^31-39; responsiveness to therapy containing LT3 might therefore depend on multiple variables, including genetic background, nutritional and lifestyle factors, stress, presence of comorbidities and autoimmune disorders, and other unidentified or poorly defined variables.^40-48

Consider screening for hypothyroidism in patients who take medication that affects either their thyroid function or the results of thyroid hormone assays.

Although combination therapy and DTE are not generally recommended over LT4 monotherapy, they might offer better options for patients who are still symptomatic when being treated with LT4 only: In a randomized, double-blind, crossover study that compared LT4 with DTE and with LT4 + LT3, one-third of the most highly symptomatic patients who had low scores on mood, cognitive, and quality-of-life assessments improved significantly after they were switched to combination therapy or DTE.³⁴

The 2014 American Thyroid Association guidelines²⁴ do not support routine use of LT4 + LT3 in hypothyroid patients who have residual symptoms after LT4 monotherapy; however, a therapeutic trial of LT4 + LT3, while maintaining a normal serum TSH, is reasonable in selected patients. Candidates for DTE or LT4 + LT3 might include patients who do not feel well on LT4 monotherapy, are post thyroidectomy or post radioiodine therapy, or have a low serum T3 level. DTE and combination therapy are discouraged in older patients, patients who have underlying CAD, and pregnant patients.

Special treatment circumstances

A number of patient variables have the potential to alter management strategies for hypothyroidism.^{18,20,23,40,49-53}

Age, comorbidity. Older patients (> 65 years) and patients with cardiopulmonary disease or CAD should be treated with LT4, 25 to 50 mcg/d, initially; that dosage can be titrated upward by 12.5 to 25 mcg/d every 4 to 6 weeks until the TSH goal is reached—preferably, in the range of 4 to 8 mIU/L. An increase in the dosage of LT4 might be required in the presence of malabsorption (eg, gastrointestinal disorders, celiac disease) and in nephrotic syndrome.^18,20,23

Body weight. A decrease in the dosage of LT4 might be indicated in the setting of significant weight loss (> 10% body weight).²³

Continue to: Co-pharmacy

Co-pharmacy. An increase in the dosage of LT4 might be required when other drugs (eg, phenytoin, phenobarbital, rifampin, and carbamazepine) have led to an increased rate of thyroid hormone metabolism. A decrease in the dosage of LT4 might be necessary after initiation of androgen therapy.²³

Pregnancy. Women with pre-e­xisting hypothyroidism require an increase of 25% to 50% in their LT4 dosage during pregnancy to maintain a TSH level in the recommended pregnancy reference range. Thyroid function should be monitored every 4 to 6 weeks to ensure that the TSH target for each trimester is reached (first trimester, 0.1-4 mIU/L; second trimester, 0.2-4 mIU/L; third trimester, 0.3-4 mIU/L). Postpartum, LT4 can be reduced to the prepartum dosage; TSH should be checked every 4 to 6 weeks to maintain the TSH goal.²³

Estrogen therapy. Hypothyroid women who are receiving estrogen therapy might require an increase in their LT4 dosage because serum thyroxine-binding globulin levels are increased by estrogens or through other mechanisms that have not been identified.²³

Surgical candidacy. Observational studies show few adverse outcomes in surgical patients with mild (subclinical) hypothyroidism or moderate hypothyroidism; however, the risk of adverse surgical outcome might be increased in patients with severe hypothyroidism. For patients in whom surgery is planned and who have:

• subclinical hypothyroidism (elevated TSH and normal FT4), we recommend that surgery—urgent or elective—not be posptoned but proceed.
• moderate (overt) hypothyroidism who require urgent surgery, we recommend not postponing surgery, even though minor perioperative complications might develop. Such patients should be treated with LT4 as soon as the diagnosis for which surgery is required has been made. Alternatively, when moderate hypothyroidism is discovered in a patient who is being evaluated for elective surgery, we recommend postponing surgery until the euthyroid state is restored.
• severe hypothyroidism (myxedema coma [discussed in a bit]; severe clinical symptoms of chronic hypothyroidism, such as altered mental status, pericardial effusion, or heart failure; or a very low level of T4), surgery should be delayed until hypothyroidism has been treated. When emergency surgery is required for a severely hypothyroid patient, they should be treated with LT4 as soon as the diagnosis for which surgery is indicated has been made. When emergency surgery must be performed in a patient with myxedema coma, we recommend treatment with LT4 + LT3, rather than LT4 alone, often administered intravenously because LT4 is poorly absorbed in these patients.

Nonadherence. For patients who do not take LT4 regularly or do not respond to efforts to improve adherence, LT4 can be given weekly, instead of daily, although this interval is not ideal. Weekly dosing should not be used in older patients with CAD.²³

Thyroid cancer. Patients who are post total thyroidectomy for thyroid cancer need to take LT4 to treat hypothyroidism and to prevent recurrence of thyroid cancer. The goal TSH level should be based on the cancer stage and risk of recurrence and should be monitored by an endocrinologist.

Myxedema coma. This medical emergency has high mortality. Myxedema coma occurs when severe hypothyroidism leads to any, or a combination, of the following: diminished mentation; hypothermia; bradycardia; hyponatremia; hypotension; cardiovascular, respiratory, and gastrointestinal dysfunction; and renal insufficiency. LT4, LT3, and glucocorticoids should be administered intravenously and the patient monitored closely—preferably in consultation with an endocrinologist.

Continue to: When to seek consultation

A patient with hypothyroidism should be referred to Endocrinology if they are < 18 years of age, pregnant, unresponsive to therapy, or have cardiac disease, coexisting endocrine disease, suspected myxedema coma, goiter or thyroid nodules, or a structural thyroid abnormality.

What we know about nutrition and hypothyroidism

Although it is commonly recognized that iodine is essential for production of thyroid hormone, other nutritional factors might contribute to proper production of thyroid hormones, including:

• adequate intake of iron, tyrosine, selenium, zinc, and vitamins E, B₂, B₃, B₆, C, and D^44,45
• selenium and zinc, which increase conversion of T4 to T3 and might be important in the management of hypothyroid patients^40,46
• vitamin A, zinc, and regular exercise, which have been shown to improve cellular sensitivity to thyroid hormones.

Low iron stores can contribute to persistent symptoms and poor quality of life in patients with hypothyroidism, despite their being treated according to guidelines.^29,47

Despite what is known about these nutritional connections, there is insufficient evidence that improving nutrition can reverse hypothyroidism.

Prevention

Prevention of hypothyroidism should take into account variables that affect or inhibit thyroid function, such as stress, infection (eg, Epstein-Barr virus), excessive fluoride intake, toxins (eg, pesticides, solvents, mercury, cadmium, and lead), autoimmune disease (eg, celiac disease), and food sensitivity.^54,55 Oxidative stress can also cause thyroid impairment.^40-48,54-58

Otherwise, there are, at present, no effective strategies for preventing thyroid disorders.

Subclinical hypothyroidism: Elusive management target

Subclinical hypothyroidism is defined as a normal serum FT4 level in the presence of an elevated serum TSH level. The prevalence of subclinical hypothyroidism varies from 3% to 15%, depending on the population studied; a higher incidence has been noted in women and older people.⁵⁹ In the NHANES III,¹ which excluded people with previously diagnosed thyroid disease, the incidence of subclinical hypothyroidism was 4.3%.

Continue to: Causes of subclinical...

Causes of subclinical hypothyroidism are the same as those of overt hypothyroidism, and include Hashimoto disease. The combination of an elevated TSH level and a normal FT4 level is associated with disorders characterized by protein-binding variations (eg, pregnancy, genetic disorders, drugs), TSH-secreting pituitary adenoma, class II and III obesity (respectively, body mass index, ≥ 35 but < 40 and ≥ 40), and assay variability.^49,51

Lab diagnosis: Fraught with difficulty

The serum TSH level and either the total T4 level or the FT4 level should be measured to make a diagnosis of subclinical hypothyroidism. Most laboratories use a 1-step analogue immunoassay to determine free thyroid hormones; protein-binding variations can thus affect measurement of FT4.

Increasing the dosage of the tablet form of LT4 (while monitoring the TSH level), is more cost effective than moving to an alternative preparation, such as a softgel or liquid.

Several scenarios that can result in inaccurate measurement of FT4 by radioimmunoassay include genetic disorders that affect binding proteins; pregnancy; use of certain drugs, including heparin, furosemide, antiepileptic agents, salicylate, ferrous sulfate, and cholesterol-binding resins; and some medical conditions, including cardiac surgery, critical illness, and renal failure. Variables that inhibit proper production of thyroid hormones—stress, infection, fluoride (an iodine antagonist), toxins (pesticides, mercury, cadmium, lead) and autoimmune conditions, such as celiac disease—should be considered when attempting to determine the cause of subclinical hypothyroidism.

Liquid chromatography–mass spectrometry measurement of thyroid hormones might be more accurate than immunoassay.⁵³ Measuring serum total T4 and FT4 by dialysis, free from interfering proteins, might also be useful when measurement of FT4 by immunoassay is affected by binding-protein variations.

Prescribe a brand-name preparation of levothyroxine whenever possible; generic formulations might have variable potency or contain other ingredients.

Features of subclinical hypothyroidism

Most patients who have subclinical hypothyroidism and a serum TSH level < 10 mIU/L are asymptomatic. Some might have nonspecific symptoms of hypothyroidism, however, such as reduced quality of life, poor cognitive function, and poor memory—symptoms that do not typically correlate with the serum TSH level.

An increase in the dosage of LT4 might be required in pregnancy or when weight gain is significant (> 10% of body weight).

It has been suggested that some elderly people normally have a higher level of serum TSH, and that they might have even a prolonged lifespan.⁵¹ Additionally, it has been shown that, in nonpregnant adult patients with subclinical hypothyroidism and a serum TSH level of 4.5 to 10 mIU/L, treatment with LT4 was not associated with improvement in thyroid-related symptoms or general quality of life.⁵²

Treat, or don't treat, subclinical hypothyroidism?

It is well accepted that the goal of therapy in hypothyroid patients is to normalize the serum TSH level; however, the American Thyroid Association and the American Association of Clinical Endocrinology recommend starting LT4 in patients with a serum TSH level ≥ 10 mIU/L (TABLE 5).^59-62 The principal reason for not treating subclinical hypothyroidism is the lack of benefit in reducing the risk of cardiovascular morbidity and mortality when the TSH level is between 7.5 and 10 mIU/L.⁶²

Continue to: Routine treatment

Routine treatment of patients with a serum TSH level of 4.5 to 10 mIU/L remains controversial. When TSH is 7.0 to 9.9 mIU/L, treatment is recommended for (1) patients < 65 years and (2) for older patients (> 65 years) only when there are convincing hypothyroid symptoms because of concern about unintended overtreatment.

When the TSH level is anywhere above the upper limit of normal to 6.9 mIU/L, treatment is recommended for patients < 65 years old, patients who have a high titer of thyroid peroxidase antibodies, and patients with goiter—but not for patients > 65 years (and, especially, not for octogenarians) because their upper limit of normal could be as high as 6 to 8 mIU/L, especially if they are otherwise healthy.

Treatment should be considered for women with subclinical hypothyroidism who are trying to conceive or experiencing an infertility problem.

For patients with subclinical hypothyroidism who are not being treated, monitor thyroid function every 6 to 12 months by testing TSH and FT4.

CORRESPONDENCE
Thanh D. Hoang, DO, Division of Endocrinology, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda, MD 20889; [email protected]

The hormones thyroxine (T4) and triiodothyronine (T3), produced by the thyroid gland, are crucial for maintaining metabolism. A deficit of thyroid hormone production—hypothyroidism—is a common endocrine disorder seen in primary care.

Many patients with hypothyroidism do not achieve optimal treatment goals or see an improvement in their quality of life.

Although the diagnosis and management of hypothyroidism are considered straightforward, many patients with hypothyroidism do not achieve optimal treatment goals or see an improvement in their quality of life. In this article, we address the questionable utility of screening; outline the diagnostic approach, including the central role of laboratory testing; and explain why treatment requires a precise approach to address the range of patient types.

Epidemiology and classification

Estimates are that almost 5% of Americans 12 years or older have hypothyroidism; older people and women are more likely to develop the condition. ¹ In the US National Health and Nutrition Examination Survey (NHANES III) of 13,344 people without known thyroid disease or a family history, hypothyroidism was found in 4.6% (overt [clinical] in 0.3% and subclinical in 4.3%); 11% had a high serum thyroid peroxidase antibody level, which increases their risk of hypothyroidism, and is treated the same as hypothyroidism of other causes; and, overall, lower serum thyroid-stimulating hormone (TSH) levels were seen in Blacks, compared to Whites and Mexican Americans.¹

Copyright Steve and Myriam Oh

Primary hypothyroidism accounts for > 95% of cases of hypothyroidism, representing a failure of the thyroid gland to produce sufficient hormone. It has been shown that, in iodine-replete countries such as the United States, the prevalence of spontaneous hypothyroidism is 1% to 2%, and it is 10 times more common in women.^2,3

Central hypothyroidism is caused by insufficient stimulation of the thyroid gland by TSH, due to pituitary (secondary hypothyroidism) or hypothalamic (tertiary hypothyroidism) disease and is estimated to occur in 1 in every 20,000 to 80,000 people in the general population.⁴

How does hypothyroidism manifest?

Signs and symptoms. Manifestations of hypothyroidism range from life-threatening to minimal or no clinical signs and symptoms (TABLE W1). Signs and symptoms of low thyroid function vary by the degree of hypothyroidism at presentation.

Common signs and symptoms of low thyroid function include fatigue, weight gain, dry skin, brittle hair, hair loss, morning stiffness, muscle aches, joint pain, cold intolerance, diffuse headache, constipation, difficulty concentrating, low libido, depression, and menstrual irregularities. On physical examination, a patient might present with bradycardia, hypotension, hypothermia with slow speech or movement, coarse facial appearance, goiter, diffuse hair loss, cold hands and feet, and a prolonged Achilles tendon reflex.⁵ Skin findings, such as keratosis pilaris, palmoplantar keratoderma (thickening of the skin), and pityriasis rubra pilar, can be associated with autoimmune hypothyroidism.^6,7

Continue to: Carpal tunnel syndrome...

Carpal tunnel syndrome, plantar fasciitis, infertility or miscarriage, dyspepsia, and small intestinal bacterial overgrowth can be associated with hypothyroidism; thyroid function should therefore be assessed in patients who have any of these conditions, along with other signs and symptoms of low thyroid function.^8,9 A patient with severe hypothyroidism might present with hemodynamic instability, pericardial or pleural effusion, and myxedema coma.¹⁰

Clues in the history and from the lab. A history of radiation to the head, neck, or chest area and a history or family history of autoimmune disorders are risk factors for autoimmune thyroid disease.^11,12 Laboratory findings can include markers of oxidative stress, such as elevated levels of low-density lipoprotein cholesterol and serum malondialdehyde.^13-15

Screening and diagnosis

Screening. The US Preventive Services Task Force has asserted that evidence is insufficient by which to evaluate the benefits and risks of routine screening for thyroid dysfunction in nonpregnant, asymptomatic adults.¹⁶ According to the American Thyroid Association and the American Association of Clinical Endocrinologists, screening should be considered in high-risk patients, including those who take medication that affects thyroid function or the results of thyroid hormone assays (TABLE W2, available at mdedge.com/familymedicine).^17-20

Screening inpatients is challenging and usually not recommended unless thyroid disease is strongly suspected. This is because changes in the levels of thyroid hormones, binding proteins, and the TSH concentration can occur in severe nonthyroidal illness; in addition, assay interference by antibodies and other substances can affect thyroid hormone measurement.²¹

Testing strategy. Generally, screening and diagnosis of hypothyroidism are based primarily on laboratory testing, because signs and symptoms are nonspecific (FIGURE 1⁵). A serum TSH level is usually the initial test when screening for thyroid dysfunction. A normal serum TSH value ranges from 0.5-5.0 mIU/L.

A patient with severe hypothyroidism might present with hemodynamic instability, pericardial or pleural effusion, or myxedema coma.

When an abnormal serum TSH level is found, further tests can be performed to investigate, including a serum free thyroxine (FT4) test. (Our preference is to order TSH and FT4 assays simultaneously to facilitate and confirm the diagnosis.) An FT4 test measures the amount of unattached, or free, thyroxine in blood by immunoassay. A normal FT4 value usually ranges from 0.7-1.9 ng/dL.

The combination of a high TSH level and a low FT4 level could be an indication of an underactive thyroid gland (ie, clinical or overt hypothyroidism). Milder, subclinical hypothyroidism is characterized by a ­higher-than-normal TSH level but a normal FT4 level.²² Central (secondary) hypothyroidism is characterized by a low serum FT4 level and a serum TSH level that can be below the reference range, low normal, or even slightly high.⁴

Continue to: These measurements...

These measurements must be interpreted within the context of the laboratory-specific normal range for each test. Third-generation serum TSH assays are more sensitive and specific than serum FT4 measurements for hypothyroidism. FT4 is usually measured by automated analogue immunoassay, which generally provides reliable results; abnormal binding proteins or other interferences occur in some patients, however, resulting in reporting of a falsely high, or falsely low, FT4 level. In such cases, FT4 by direct dialysis, or total T4, can be measured for further evaluation. In primary care, you are most likely to encounter primary hypothyroidism; secondary (central) hypothyroidism is much rarer (< 5% of cases).⁴

The ins and outs of treatment

For most patients, hypothyroidism is a permanent disorder requiring lifelong thyroid hormone replacement therapy—unless the disease is transient (ie, painless or subacute thyroiditis); reversible, because it is caused by medication; or responsive to medical intervention that addresses the underlying autoimmune condition.¹⁹ Goals of treatment (Figure 2^5,23) are to:

• normalize the TSH level to 0.5-5.0 mIU/L (the main goal), with an age-related shift toward a higher TSH goal in older patients (and an upper limit of normal of 7.5 mIU/L in patients who are ≥ 80 years of age)²⁰
• restore the euthyroid state
• relieve symptoms
• reduce any goiter
• avoid overtreatment (iatrogenic thyrotoxicosis).

Desiccated thyroid extract (DTE), developed in the late 1880s and made from the dried thyroid gland of pigs, sheep, or cows, was the earliest treatment for hypothyroidism. The use of DTE has declined since the introduction of synthetic thyroxine (T4, or levothyroxine [here, referred to as LT4]), which is now the standard treatment.^20-22 LT4 is deiodinated in peripheral tissues to form T3, the active thyroid hormone; this process accounts for 80% of total T3 production daily.²⁴

LT4 formulations. LT4 is commercially available in tablet, soft-gel, and liquid preparations. Most patients are treated with the tablet; the soft-gel capsule or liquid is an option for patients who absorb the tablet poorly (because of atrophic gastritis, celiac disease, or gluten sensitivity or because they are post bariatric surgery). Increasing the dosage of the tablet form of LT4, with ongoing TSH monitoring, is more cost effective than moving to an alternative preparation.

If a switch of LT4 formulation is made (ie, from one manufacturer to another), test the serum TSH level to ensure that the therapeutic goal is being reached. Also, in our experience, it is best to prescribe a brand-name preparation of levothyroxine, not a generic, whenever possible, due to the variability in generic formulations and the potential presence of other (inert) ingredients.²⁵

Dosing (TABLE 3^20,23). The average full replacement dosage of LT4 for a young, healthy adult is approximately 1.6 mcg/kg/d. Older patients (> 65 years) or those with coronary artery disease (CAD) should be started on a lower dosage (25-50 mcg/d) and titrated to goal accordingly.

LT4 (tablets, soft-gel capsules, or liquid) should be administered on an empty stomach, with water only, 30 to 60 minutes before breakfast. Medications that interfere with LT4 absorption (eg, bile acid resins, calcium carbonate, ferrous sulfate) should be taken several hours after LT4. For patients who cannot take LT4 in the morning, taking it at bedtime (≥ 2-3 hours after the last meal) is acceptable.

Continue to: Monitoring and titrating

Monitoring and titrating. Hypothyroid symptoms usually improve after 2 or 3 weeks of LT4 treatment; in severe hypothyroidism, complete recovery might take months. Approximately 6 weeks after LT4 therapy is initiated, serum TSH should be measured. After assessing whether administration of LT4 at the starting dosage is appropriate, that dosage can be increased, or decreased, every 4 to 6 weeks until the TSH goal is reached. Once the patient is maintained at a given dosage, measure serum TSH once a year—more often if there is an abnormal result or a change in the patient’s health status.²³

Adverse effects of LT4 therapy are rare, unless over-replacement occurs. Rarely, patients have an allergy to the dye or an excipient (filler) in the tablet.^26-28 The white, 50-mcg tablets can be given safely to patients with dye sensitivity. For those who have an allergy to an excipient (except gelatin) or gluten intolerance, the LT4 soft-gel capsule or liquid preparation (Tirosint) can be prescribed.

Pure LT4, in a capsule made from vegetable sources, can be ordered through a compounding pharmacy for patients who are allergic to animal products.

Anemia, especially iron-deficiency anemia, can cause intolerance to LT4 therapy; in such patients, lowering the starting dosage and treating anemia are indicated.²⁹

Persistent symptoms (despite a normal TSH level). Because many hypothyroid symptoms are nonspecific, patients might come to think that their LT4 dosage is inadequate if they feel tired or gain weight. Persistent hypothyroid symptoms despite a normal serum TSH level might be due to (1) the inability of LT4 therapy to restore tissue thyroid hormone levels to normal or (2) other variables unrelated to hypothyroidism, including disorders associated with inflammation or autoimmune disease, certain medications, diet, lifestyle, and environmental toxins.

These patients might benefit from a detailed history to identify other causes and a switch to either LT4 + liothyronine (LT3; synthetic T3) combination therapy or DTE^26,30-33 (TABLE 4³⁴), although a beneficial effect of LT4 + LT3 therapy was not seen in several studies.^35,36 Over-replacement with LT4 should be discouraged, due to concerns about thyrotoxicosis and its complications (eg, atrial fibrillation, accelerated bone loss).

DTE and LT4 + LT3. Use of DTE has decreased since the 1970s, when LT4 became the therapy of choice. Subsequently, anecdotal evidence emerged that some patients did not feel well on LT4 and preferred to return to DTE.^32,33

Continue to: Several clinical trials...

Several clinical trials addressed the question of whether residual symptoms could be resolved through LT4 + LT3 combination therapy^31-39 (TABLE 4³⁴), but evidence of any consistent superiority of combination therapy was not demonstrated.^35-39 In selected cases, patients might prefer the combination approach.^31,33,39 The quality of life of hypothyroid patients was found to be similarly improved with LT4 or DTE, but the latter was associated with modest weight loss (approximately 4 lbs); nearly 50% of study patients preferred treatment with DTE over LT4.³³ A follow-up study did not confirm weight loss with DTE, however.³⁴

When LT4 monotherapy and LT4 + LT3 combination therapy were compared, results were mixed^31-39; responsiveness to therapy containing LT3 might therefore depend on multiple variables, including genetic background, nutritional and lifestyle factors, stress, presence of comorbidities and autoimmune disorders, and other unidentified or poorly defined variables.^40-48

Consider screening for hypothyroidism in patients who take medication that affects either their thyroid function or the results of thyroid hormone assays.

Although combination therapy and DTE are not generally recommended over LT4 monotherapy, they might offer better options for patients who are still symptomatic when being treated with LT4 only: In a randomized, double-blind, crossover study that compared LT4 with DTE and with LT4 + LT3, one-third of the most highly symptomatic patients who had low scores on mood, cognitive, and quality-of-life assessments improved significantly after they were switched to combination therapy or DTE.³⁴

The 2014 American Thyroid Association guidelines²⁴ do not support routine use of LT4 + LT3 in hypothyroid patients who have residual symptoms after LT4 monotherapy; however, a therapeutic trial of LT4 + LT3, while maintaining a normal serum TSH, is reasonable in selected patients. Candidates for DTE or LT4 + LT3 might include patients who do not feel well on LT4 monotherapy, are post thyroidectomy or post radioiodine therapy, or have a low serum T3 level. DTE and combination therapy are discouraged in older patients, patients who have underlying CAD, and pregnant patients.

Special treatment circumstances

A number of patient variables have the potential to alter management strategies for hypothyroidism.^{18,20,23,40,49-53}

Age, comorbidity. Older patients (> 65 years) and patients with cardiopulmonary disease or CAD should be treated with LT4, 25 to 50 mcg/d, initially; that dosage can be titrated upward by 12.5 to 25 mcg/d every 4 to 6 weeks until the TSH goal is reached—preferably, in the range of 4 to 8 mIU/L. An increase in the dosage of LT4 might be required in the presence of malabsorption (eg, gastrointestinal disorders, celiac disease) and in nephrotic syndrome.^18,20,23

Body weight. A decrease in the dosage of LT4 might be indicated in the setting of significant weight loss (> 10% body weight).²³

Continue to: Co-pharmacy

Co-pharmacy. An increase in the dosage of LT4 might be required when other drugs (eg, phenytoin, phenobarbital, rifampin, and carbamazepine) have led to an increased rate of thyroid hormone metabolism. A decrease in the dosage of LT4 might be necessary after initiation of androgen therapy.²³

Pregnancy. Women with pre-e­xisting hypothyroidism require an increase of 25% to 50% in their LT4 dosage during pregnancy to maintain a TSH level in the recommended pregnancy reference range. Thyroid function should be monitored every 4 to 6 weeks to ensure that the TSH target for each trimester is reached (first trimester, 0.1-4 mIU/L; second trimester, 0.2-4 mIU/L; third trimester, 0.3-4 mIU/L). Postpartum, LT4 can be reduced to the prepartum dosage; TSH should be checked every 4 to 6 weeks to maintain the TSH goal.²³

Estrogen therapy. Hypothyroid women who are receiving estrogen therapy might require an increase in their LT4 dosage because serum thyroxine-binding globulin levels are increased by estrogens or through other mechanisms that have not been identified.²³

Surgical candidacy. Observational studies show few adverse outcomes in surgical patients with mild (subclinical) hypothyroidism or moderate hypothyroidism; however, the risk of adverse surgical outcome might be increased in patients with severe hypothyroidism. For patients in whom surgery is planned and who have:

• subclinical hypothyroidism (elevated TSH and normal FT4), we recommend that surgery—urgent or elective—not be posptoned but proceed.
• moderate (overt) hypothyroidism who require urgent surgery, we recommend not postponing surgery, even though minor perioperative complications might develop. Such patients should be treated with LT4 as soon as the diagnosis for which surgery is required has been made. Alternatively, when moderate hypothyroidism is discovered in a patient who is being evaluated for elective surgery, we recommend postponing surgery until the euthyroid state is restored.
• severe hypothyroidism (myxedema coma [discussed in a bit]; severe clinical symptoms of chronic hypothyroidism, such as altered mental status, pericardial effusion, or heart failure; or a very low level of T4), surgery should be delayed until hypothyroidism has been treated. When emergency surgery is required for a severely hypothyroid patient, they should be treated with LT4 as soon as the diagnosis for which surgery is indicated has been made. When emergency surgery must be performed in a patient with myxedema coma, we recommend treatment with LT4 + LT3, rather than LT4 alone, often administered intravenously because LT4 is poorly absorbed in these patients.

Nonadherence. For patients who do not take LT4 regularly or do not respond to efforts to improve adherence, LT4 can be given weekly, instead of daily, although this interval is not ideal. Weekly dosing should not be used in older patients with CAD.²³

Thyroid cancer. Patients who are post total thyroidectomy for thyroid cancer need to take LT4 to treat hypothyroidism and to prevent recurrence of thyroid cancer. The goal TSH level should be based on the cancer stage and risk of recurrence and should be monitored by an endocrinologist.

Myxedema coma. This medical emergency has high mortality. Myxedema coma occurs when severe hypothyroidism leads to any, or a combination, of the following: diminished mentation; hypothermia; bradycardia; hyponatremia; hypotension; cardiovascular, respiratory, and gastrointestinal dysfunction; and renal insufficiency. LT4, LT3, and glucocorticoids should be administered intravenously and the patient monitored closely—preferably in consultation with an endocrinologist.

Continue to: When to seek consultation

A patient with hypothyroidism should be referred to Endocrinology if they are < 18 years of age, pregnant, unresponsive to therapy, or have cardiac disease, coexisting endocrine disease, suspected myxedema coma, goiter or thyroid nodules, or a structural thyroid abnormality.

What we know about nutrition and hypothyroidism

Although it is commonly recognized that iodine is essential for production of thyroid hormone, other nutritional factors might contribute to proper production of thyroid hormones, including:

• adequate intake of iron, tyrosine, selenium, zinc, and vitamins E, B₂, B₃, B₆, C, and D^44,45
• selenium and zinc, which increase conversion of T4 to T3 and might be important in the management of hypothyroid patients^40,46
• vitamin A, zinc, and regular exercise, which have been shown to improve cellular sensitivity to thyroid hormones.

Low iron stores can contribute to persistent symptoms and poor quality of life in patients with hypothyroidism, despite their being treated according to guidelines.^29,47

Despite what is known about these nutritional connections, there is insufficient evidence that improving nutrition can reverse hypothyroidism.

Prevention

Prevention of hypothyroidism should take into account variables that affect or inhibit thyroid function, such as stress, infection (eg, Epstein-Barr virus), excessive fluoride intake, toxins (eg, pesticides, solvents, mercury, cadmium, and lead), autoimmune disease (eg, celiac disease), and food sensitivity.^54,55 Oxidative stress can also cause thyroid impairment.^40-48,54-58

Otherwise, there are, at present, no effective strategies for preventing thyroid disorders.

Subclinical hypothyroidism: Elusive management target

Subclinical hypothyroidism is defined as a normal serum FT4 level in the presence of an elevated serum TSH level. The prevalence of subclinical hypothyroidism varies from 3% to 15%, depending on the population studied; a higher incidence has been noted in women and older people.⁵⁹ In the NHANES III,¹ which excluded people with previously diagnosed thyroid disease, the incidence of subclinical hypothyroidism was 4.3%.

Continue to: Causes of subclinical...

Causes of subclinical hypothyroidism are the same as those of overt hypothyroidism, and include Hashimoto disease. The combination of an elevated TSH level and a normal FT4 level is associated with disorders characterized by protein-binding variations (eg, pregnancy, genetic disorders, drugs), TSH-secreting pituitary adenoma, class II and III obesity (respectively, body mass index, ≥ 35 but < 40 and ≥ 40), and assay variability.^49,51

Lab diagnosis: Fraught with difficulty

The serum TSH level and either the total T4 level or the FT4 level should be measured to make a diagnosis of subclinical hypothyroidism. Most laboratories use a 1-step analogue immunoassay to determine free thyroid hormones; protein-binding variations can thus affect measurement of FT4.

Increasing the dosage of the tablet form of LT4 (while monitoring the TSH level), is more cost effective than moving to an alternative preparation, such as a softgel or liquid.

Several scenarios that can result in inaccurate measurement of FT4 by radioimmunoassay include genetic disorders that affect binding proteins; pregnancy; use of certain drugs, including heparin, furosemide, antiepileptic agents, salicylate, ferrous sulfate, and cholesterol-binding resins; and some medical conditions, including cardiac surgery, critical illness, and renal failure. Variables that inhibit proper production of thyroid hormones—stress, infection, fluoride (an iodine antagonist), toxins (pesticides, mercury, cadmium, lead) and autoimmune conditions, such as celiac disease—should be considered when attempting to determine the cause of subclinical hypothyroidism.

Liquid chromatography–mass spectrometry measurement of thyroid hormones might be more accurate than immunoassay.⁵³ Measuring serum total T4 and FT4 by dialysis, free from interfering proteins, might also be useful when measurement of FT4 by immunoassay is affected by binding-protein variations.

Prescribe a brand-name preparation of levothyroxine whenever possible; generic formulations might have variable potency or contain other ingredients.

Features of subclinical hypothyroidism

Most patients who have subclinical hypothyroidism and a serum TSH level < 10 mIU/L are asymptomatic. Some might have nonspecific symptoms of hypothyroidism, however, such as reduced quality of life, poor cognitive function, and poor memory—symptoms that do not typically correlate with the serum TSH level.

An increase in the dosage of LT4 might be required in pregnancy or when weight gain is significant (> 10% of body weight).

It has been suggested that some elderly people normally have a higher level of serum TSH, and that they might have even a prolonged lifespan.⁵¹ Additionally, it has been shown that, in nonpregnant adult patients with subclinical hypothyroidism and a serum TSH level of 4.5 to 10 mIU/L, treatment with LT4 was not associated with improvement in thyroid-related symptoms or general quality of life.⁵²

Treat, or don't treat, subclinical hypothyroidism?

It is well accepted that the goal of therapy in hypothyroid patients is to normalize the serum TSH level; however, the American Thyroid Association and the American Association of Clinical Endocrinology recommend starting LT4 in patients with a serum TSH level ≥ 10 mIU/L (TABLE 5).^59-62 The principal reason for not treating subclinical hypothyroidism is the lack of benefit in reducing the risk of cardiovascular morbidity and mortality when the TSH level is between 7.5 and 10 mIU/L.⁶²

Continue to: Routine treatment

Routine treatment of patients with a serum TSH level of 4.5 to 10 mIU/L remains controversial. When TSH is 7.0 to 9.9 mIU/L, treatment is recommended for (1) patients < 65 years and (2) for older patients (> 65 years) only when there are convincing hypothyroid symptoms because of concern about unintended overtreatment.

When the TSH level is anywhere above the upper limit of normal to 6.9 mIU/L, treatment is recommended for patients < 65 years old, patients who have a high titer of thyroid peroxidase antibodies, and patients with goiter—but not for patients > 65 years (and, especially, not for octogenarians) because their upper limit of normal could be as high as 6 to 8 mIU/L, especially if they are otherwise healthy.

Treatment should be considered for women with subclinical hypothyroidism who are trying to conceive or experiencing an infertility problem.

For patients with subclinical hypothyroidism who are not being treated, monitor thyroid function every 6 to 12 months by testing TSH and FT4.

CORRESPONDENCE
Thanh D. Hoang, DO, Division of Endocrinology, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda, MD 20889; [email protected]

The hormones thyroxine (T4) and triiodothyronine (T3), produced by the thyroid gland, are crucial for maintaining metabolism. A deficit of thyroid hormone production—hypothyroidism—is a common endocrine disorder seen in primary care.

Many patients with hypothyroidism do not achieve optimal treatment goals or see an improvement in their quality of life.

Although the diagnosis and management of hypothyroidism are considered straightforward, many patients with hypothyroidism do not achieve optimal treatment goals or see an improvement in their quality of life. In this article, we address the questionable utility of screening; outline the diagnostic approach, including the central role of laboratory testing; and explain why treatment requires a precise approach to address the range of patient types.

Epidemiology and classification

Estimates are that almost 5% of Americans 12 years or older have hypothyroidism; older people and women are more likely to develop the condition. ¹ In the US National Health and Nutrition Examination Survey (NHANES III) of 13,344 people without known thyroid disease or a family history, hypothyroidism was found in 4.6% (overt [clinical] in 0.3% and subclinical in 4.3%); 11% had a high serum thyroid peroxidase antibody level, which increases their risk of hypothyroidism, and is treated the same as hypothyroidism of other causes; and, overall, lower serum thyroid-stimulating hormone (TSH) levels were seen in Blacks, compared to Whites and Mexican Americans.¹

Copyright Steve and Myriam Oh

Primary hypothyroidism accounts for > 95% of cases of hypothyroidism, representing a failure of the thyroid gland to produce sufficient hormone. It has been shown that, in iodine-replete countries such as the United States, the prevalence of spontaneous hypothyroidism is 1% to 2%, and it is 10 times more common in women.^2,3

Central hypothyroidism is caused by insufficient stimulation of the thyroid gland by TSH, due to pituitary (secondary hypothyroidism) or hypothalamic (tertiary hypothyroidism) disease and is estimated to occur in 1 in every 20,000 to 80,000 people in the general population.⁴

How does hypothyroidism manifest?

Signs and symptoms. Manifestations of hypothyroidism range from life-threatening to minimal or no clinical signs and symptoms (TABLE W1). Signs and symptoms of low thyroid function vary by the degree of hypothyroidism at presentation.

Common signs and symptoms of low thyroid function include fatigue, weight gain, dry skin, brittle hair, hair loss, morning stiffness, muscle aches, joint pain, cold intolerance, diffuse headache, constipation, difficulty concentrating, low libido, depression, and menstrual irregularities. On physical examination, a patient might present with bradycardia, hypotension, hypothermia with slow speech or movement, coarse facial appearance, goiter, diffuse hair loss, cold hands and feet, and a prolonged Achilles tendon reflex.⁵ Skin findings, such as keratosis pilaris, palmoplantar keratoderma (thickening of the skin), and pityriasis rubra pilar, can be associated with autoimmune hypothyroidism.^6,7

Continue to: Carpal tunnel syndrome...

Carpal tunnel syndrome, plantar fasciitis, infertility or miscarriage, dyspepsia, and small intestinal bacterial overgrowth can be associated with hypothyroidism; thyroid function should therefore be assessed in patients who have any of these conditions, along with other signs and symptoms of low thyroid function.^8,9 A patient with severe hypothyroidism might present with hemodynamic instability, pericardial or pleural effusion, and myxedema coma.¹⁰

Clues in the history and from the lab. A history of radiation to the head, neck, or chest area and a history or family history of autoimmune disorders are risk factors for autoimmune thyroid disease.^11,12 Laboratory findings can include markers of oxidative stress, such as elevated levels of low-density lipoprotein cholesterol and serum malondialdehyde.^13-15

Screening and diagnosis

Screening. The US Preventive Services Task Force has asserted that evidence is insufficient by which to evaluate the benefits and risks of routine screening for thyroid dysfunction in nonpregnant, asymptomatic adults.¹⁶ According to the American Thyroid Association and the American Association of Clinical Endocrinologists, screening should be considered in high-risk patients, including those who take medication that affects thyroid function or the results of thyroid hormone assays (TABLE W2, available at mdedge.com/familymedicine).^17-20

Screening inpatients is challenging and usually not recommended unless thyroid disease is strongly suspected. This is because changes in the levels of thyroid hormones, binding proteins, and the TSH concentration can occur in severe nonthyroidal illness; in addition, assay interference by antibodies and other substances can affect thyroid hormone measurement.²¹

Testing strategy. Generally, screening and diagnosis of hypothyroidism are based primarily on laboratory testing, because signs and symptoms are nonspecific (FIGURE 1⁵). A serum TSH level is usually the initial test when screening for thyroid dysfunction. A normal serum TSH value ranges from 0.5-5.0 mIU/L.

A patient with severe hypothyroidism might present with hemodynamic instability, pericardial or pleural effusion, or myxedema coma.

When an abnormal serum TSH level is found, further tests can be performed to investigate, including a serum free thyroxine (FT4) test. (Our preference is to order TSH and FT4 assays simultaneously to facilitate and confirm the diagnosis.) An FT4 test measures the amount of unattached, or free, thyroxine in blood by immunoassay. A normal FT4 value usually ranges from 0.7-1.9 ng/dL.

The combination of a high TSH level and a low FT4 level could be an indication of an underactive thyroid gland (ie, clinical or overt hypothyroidism). Milder, subclinical hypothyroidism is characterized by a ­higher-than-normal TSH level but a normal FT4 level.²² Central (secondary) hypothyroidism is characterized by a low serum FT4 level and a serum TSH level that can be below the reference range, low normal, or even slightly high.⁴

Continue to: These measurements...

These measurements must be interpreted within the context of the laboratory-specific normal range for each test. Third-generation serum TSH assays are more sensitive and specific than serum FT4 measurements for hypothyroidism. FT4 is usually measured by automated analogue immunoassay, which generally provides reliable results; abnormal binding proteins or other interferences occur in some patients, however, resulting in reporting of a falsely high, or falsely low, FT4 level. In such cases, FT4 by direct dialysis, or total T4, can be measured for further evaluation. In primary care, you are most likely to encounter primary hypothyroidism; secondary (central) hypothyroidism is much rarer (< 5% of cases).⁴

The ins and outs of treatment

For most patients, hypothyroidism is a permanent disorder requiring lifelong thyroid hormone replacement therapy—unless the disease is transient (ie, painless or subacute thyroiditis); reversible, because it is caused by medication; or responsive to medical intervention that addresses the underlying autoimmune condition.¹⁹ Goals of treatment (Figure 2^5,23) are to:

• normalize the TSH level to 0.5-5.0 mIU/L (the main goal), with an age-related shift toward a higher TSH goal in older patients (and an upper limit of normal of 7.5 mIU/L in patients who are ≥ 80 years of age)²⁰
• restore the euthyroid state
• relieve symptoms
• reduce any goiter
• avoid overtreatment (iatrogenic thyrotoxicosis).

Desiccated thyroid extract (DTE), developed in the late 1880s and made from the dried thyroid gland of pigs, sheep, or cows, was the earliest treatment for hypothyroidism. The use of DTE has declined since the introduction of synthetic thyroxine (T4, or levothyroxine [here, referred to as LT4]), which is now the standard treatment.^20-22 LT4 is deiodinated in peripheral tissues to form T3, the active thyroid hormone; this process accounts for 80% of total T3 production daily.²⁴

LT4 formulations. LT4 is commercially available in tablet, soft-gel, and liquid preparations. Most patients are treated with the tablet; the soft-gel capsule or liquid is an option for patients who absorb the tablet poorly (because of atrophic gastritis, celiac disease, or gluten sensitivity or because they are post bariatric surgery). Increasing the dosage of the tablet form of LT4, with ongoing TSH monitoring, is more cost effective than moving to an alternative preparation.

If a switch of LT4 formulation is made (ie, from one manufacturer to another), test the serum TSH level to ensure that the therapeutic goal is being reached. Also, in our experience, it is best to prescribe a brand-name preparation of levothyroxine, not a generic, whenever possible, due to the variability in generic formulations and the potential presence of other (inert) ingredients.²⁵

Dosing (TABLE 3^20,23). The average full replacement dosage of LT4 for a young, healthy adult is approximately 1.6 mcg/kg/d. Older patients (> 65 years) or those with coronary artery disease (CAD) should be started on a lower dosage (25-50 mcg/d) and titrated to goal accordingly.

LT4 (tablets, soft-gel capsules, or liquid) should be administered on an empty stomach, with water only, 30 to 60 minutes before breakfast. Medications that interfere with LT4 absorption (eg, bile acid resins, calcium carbonate, ferrous sulfate) should be taken several hours after LT4. For patients who cannot take LT4 in the morning, taking it at bedtime (≥ 2-3 hours after the last meal) is acceptable.

Continue to: Monitoring and titrating

Monitoring and titrating. Hypothyroid symptoms usually improve after 2 or 3 weeks of LT4 treatment; in severe hypothyroidism, complete recovery might take months. Approximately 6 weeks after LT4 therapy is initiated, serum TSH should be measured. After assessing whether administration of LT4 at the starting dosage is appropriate, that dosage can be increased, or decreased, every 4 to 6 weeks until the TSH goal is reached. Once the patient is maintained at a given dosage, measure serum TSH once a year—more often if there is an abnormal result or a change in the patient’s health status.²³

Adverse effects of LT4 therapy are rare, unless over-replacement occurs. Rarely, patients have an allergy to the dye or an excipient (filler) in the tablet.^26-28 The white, 50-mcg tablets can be given safely to patients with dye sensitivity. For those who have an allergy to an excipient (except gelatin) or gluten intolerance, the LT4 soft-gel capsule or liquid preparation (Tirosint) can be prescribed.

Pure LT4, in a capsule made from vegetable sources, can be ordered through a compounding pharmacy for patients who are allergic to animal products.

Anemia, especially iron-deficiency anemia, can cause intolerance to LT4 therapy; in such patients, lowering the starting dosage and treating anemia are indicated.²⁹

Persistent symptoms (despite a normal TSH level). Because many hypothyroid symptoms are nonspecific, patients might come to think that their LT4 dosage is inadequate if they feel tired or gain weight. Persistent hypothyroid symptoms despite a normal serum TSH level might be due to (1) the inability of LT4 therapy to restore tissue thyroid hormone levels to normal or (2) other variables unrelated to hypothyroidism, including disorders associated with inflammation or autoimmune disease, certain medications, diet, lifestyle, and environmental toxins.

These patients might benefit from a detailed history to identify other causes and a switch to either LT4 + liothyronine (LT3; synthetic T3) combination therapy or DTE^26,30-33 (TABLE 4³⁴), although a beneficial effect of LT4 + LT3 therapy was not seen in several studies.^35,36 Over-replacement with LT4 should be discouraged, due to concerns about thyrotoxicosis and its complications (eg, atrial fibrillation, accelerated bone loss).

DTE and LT4 + LT3. Use of DTE has decreased since the 1970s, when LT4 became the therapy of choice. Subsequently, anecdotal evidence emerged that some patients did not feel well on LT4 and preferred to return to DTE.^32,33

Continue to: Several clinical trials...

Several clinical trials addressed the question of whether residual symptoms could be resolved through LT4 + LT3 combination therapy^31-39 (TABLE 4³⁴), but evidence of any consistent superiority of combination therapy was not demonstrated.^35-39 In selected cases, patients might prefer the combination approach.^31,33,39 The quality of life of hypothyroid patients was found to be similarly improved with LT4 or DTE, but the latter was associated with modest weight loss (approximately 4 lbs); nearly 50% of study patients preferred treatment with DTE over LT4.³³ A follow-up study did not confirm weight loss with DTE, however.³⁴

When LT4 monotherapy and LT4 + LT3 combination therapy were compared, results were mixed^31-39; responsiveness to therapy containing LT3 might therefore depend on multiple variables, including genetic background, nutritional and lifestyle factors, stress, presence of comorbidities and autoimmune disorders, and other unidentified or poorly defined variables.^40-48

Consider screening for hypothyroidism in patients who take medication that affects either their thyroid function or the results of thyroid hormone assays.

Although combination therapy and DTE are not generally recommended over LT4 monotherapy, they might offer better options for patients who are still symptomatic when being treated with LT4 only: In a randomized, double-blind, crossover study that compared LT4 with DTE and with LT4 + LT3, one-third of the most highly symptomatic patients who had low scores on mood, cognitive, and quality-of-life assessments improved significantly after they were switched to combination therapy or DTE.³⁴

The 2014 American Thyroid Association guidelines²⁴ do not support routine use of LT4 + LT3 in hypothyroid patients who have residual symptoms after LT4 monotherapy; however, a therapeutic trial of LT4 + LT3, while maintaining a normal serum TSH, is reasonable in selected patients. Candidates for DTE or LT4 + LT3 might include patients who do not feel well on LT4 monotherapy, are post thyroidectomy or post radioiodine therapy, or have a low serum T3 level. DTE and combination therapy are discouraged in older patients, patients who have underlying CAD, and pregnant patients.

Special treatment circumstances

A number of patient variables have the potential to alter management strategies for hypothyroidism.^{18,20,23,40,49-53}

Age, comorbidity. Older patients (> 65 years) and patients with cardiopulmonary disease or CAD should be treated with LT4, 25 to 50 mcg/d, initially; that dosage can be titrated upward by 12.5 to 25 mcg/d every 4 to 6 weeks until the TSH goal is reached—preferably, in the range of 4 to 8 mIU/L. An increase in the dosage of LT4 might be required in the presence of malabsorption (eg, gastrointestinal disorders, celiac disease) and in nephrotic syndrome.^18,20,23

Body weight. A decrease in the dosage of LT4 might be indicated in the setting of significant weight loss (> 10% body weight).²³

Continue to: Co-pharmacy

Co-pharmacy. An increase in the dosage of LT4 might be required when other drugs (eg, phenytoin, phenobarbital, rifampin, and carbamazepine) have led to an increased rate of thyroid hormone metabolism. A decrease in the dosage of LT4 might be necessary after initiation of androgen therapy.²³

Pregnancy. Women with pre-e­xisting hypothyroidism require an increase of 25% to 50% in their LT4 dosage during pregnancy to maintain a TSH level in the recommended pregnancy reference range. Thyroid function should be monitored every 4 to 6 weeks to ensure that the TSH target for each trimester is reached (first trimester, 0.1-4 mIU/L; second trimester, 0.2-4 mIU/L; third trimester, 0.3-4 mIU/L). Postpartum, LT4 can be reduced to the prepartum dosage; TSH should be checked every 4 to 6 weeks to maintain the TSH goal.²³

Estrogen therapy. Hypothyroid women who are receiving estrogen therapy might require an increase in their LT4 dosage because serum thyroxine-binding globulin levels are increased by estrogens or through other mechanisms that have not been identified.²³

Surgical candidacy. Observational studies show few adverse outcomes in surgical patients with mild (subclinical) hypothyroidism or moderate hypothyroidism; however, the risk of adverse surgical outcome might be increased in patients with severe hypothyroidism. For patients in whom surgery is planned and who have:

• subclinical hypothyroidism (elevated TSH and normal FT4), we recommend that surgery—urgent or elective—not be posptoned but proceed.
• moderate (overt) hypothyroidism who require urgent surgery, we recommend not postponing surgery, even though minor perioperative complications might develop. Such patients should be treated with LT4 as soon as the diagnosis for which surgery is required has been made. Alternatively, when moderate hypothyroidism is discovered in a patient who is being evaluated for elective surgery, we recommend postponing surgery until the euthyroid state is restored.
• severe hypothyroidism (myxedema coma [discussed in a bit]; severe clinical symptoms of chronic hypothyroidism, such as altered mental status, pericardial effusion, or heart failure; or a very low level of T4), surgery should be delayed until hypothyroidism has been treated. When emergency surgery is required for a severely hypothyroid patient, they should be treated with LT4 as soon as the diagnosis for which surgery is indicated has been made. When emergency surgery must be performed in a patient with myxedema coma, we recommend treatment with LT4 + LT3, rather than LT4 alone, often administered intravenously because LT4 is poorly absorbed in these patients.

Nonadherence. For patients who do not take LT4 regularly or do not respond to efforts to improve adherence, LT4 can be given weekly, instead of daily, although this interval is not ideal. Weekly dosing should not be used in older patients with CAD.²³

Thyroid cancer. Patients who are post total thyroidectomy for thyroid cancer need to take LT4 to treat hypothyroidism and to prevent recurrence of thyroid cancer. The goal TSH level should be based on the cancer stage and risk of recurrence and should be monitored by an endocrinologist.

Myxedema coma. This medical emergency has high mortality. Myxedema coma occurs when severe hypothyroidism leads to any, or a combination, of the following: diminished mentation; hypothermia; bradycardia; hyponatremia; hypotension; cardiovascular, respiratory, and gastrointestinal dysfunction; and renal insufficiency. LT4, LT3, and glucocorticoids should be administered intravenously and the patient monitored closely—preferably in consultation with an endocrinologist.

Continue to: When to seek consultation

A patient with hypothyroidism should be referred to Endocrinology if they are < 18 years of age, pregnant, unresponsive to therapy, or have cardiac disease, coexisting endocrine disease, suspected myxedema coma, goiter or thyroid nodules, or a structural thyroid abnormality.

What we know about nutrition and hypothyroidism

Although it is commonly recognized that iodine is essential for production of thyroid hormone, other nutritional factors might contribute to proper production of thyroid hormones, including:

• adequate intake of iron, tyrosine, selenium, zinc, and vitamins E, B₂, B₃, B₆, C, and D^44,45
• selenium and zinc, which increase conversion of T4 to T3 and might be important in the management of hypothyroid patients^40,46
• vitamin A, zinc, and regular exercise, which have been shown to improve cellular sensitivity to thyroid hormones.

Low iron stores can contribute to persistent symptoms and poor quality of life in patients with hypothyroidism, despite their being treated according to guidelines.^29,47

Despite what is known about these nutritional connections, there is insufficient evidence that improving nutrition can reverse hypothyroidism.

Prevention

Prevention of hypothyroidism should take into account variables that affect or inhibit thyroid function, such as stress, infection (eg, Epstein-Barr virus), excessive fluoride intake, toxins (eg, pesticides, solvents, mercury, cadmium, and lead), autoimmune disease (eg, celiac disease), and food sensitivity.^54,55 Oxidative stress can also cause thyroid impairment.^40-48,54-58

Otherwise, there are, at present, no effective strategies for preventing thyroid disorders.

Subclinical hypothyroidism: Elusive management target

Subclinical hypothyroidism is defined as a normal serum FT4 level in the presence of an elevated serum TSH level. The prevalence of subclinical hypothyroidism varies from 3% to 15%, depending on the population studied; a higher incidence has been noted in women and older people.⁵⁹ In the NHANES III,¹ which excluded people with previously diagnosed thyroid disease, the incidence of subclinical hypothyroidism was 4.3%.

Continue to: Causes of subclinical...

Causes of subclinical hypothyroidism are the same as those of overt hypothyroidism, and include Hashimoto disease. The combination of an elevated TSH level and a normal FT4 level is associated with disorders characterized by protein-binding variations (eg, pregnancy, genetic disorders, drugs), TSH-secreting pituitary adenoma, class II and III obesity (respectively, body mass index, ≥ 35 but < 40 and ≥ 40), and assay variability.^49,51

Lab diagnosis: Fraught with difficulty

The serum TSH level and either the total T4 level or the FT4 level should be measured to make a diagnosis of subclinical hypothyroidism. Most laboratories use a 1-step analogue immunoassay to determine free thyroid hormones; protein-binding variations can thus affect measurement of FT4.

Increasing the dosage of the tablet form of LT4 (while monitoring the TSH level), is more cost effective than moving to an alternative preparation, such as a softgel or liquid.

Several scenarios that can result in inaccurate measurement of FT4 by radioimmunoassay include genetic disorders that affect binding proteins; pregnancy; use of certain drugs, including heparin, furosemide, antiepileptic agents, salicylate, ferrous sulfate, and cholesterol-binding resins; and some medical conditions, including cardiac surgery, critical illness, and renal failure. Variables that inhibit proper production of thyroid hormones—stress, infection, fluoride (an iodine antagonist), toxins (pesticides, mercury, cadmium, lead) and autoimmune conditions, such as celiac disease—should be considered when attempting to determine the cause of subclinical hypothyroidism.

Liquid chromatography–mass spectrometry measurement of thyroid hormones might be more accurate than immunoassay.⁵³ Measuring serum total T4 and FT4 by dialysis, free from interfering proteins, might also be useful when measurement of FT4 by immunoassay is affected by binding-protein variations.

Prescribe a brand-name preparation of levothyroxine whenever possible; generic formulations might have variable potency or contain other ingredients.

Features of subclinical hypothyroidism

Most patients who have subclinical hypothyroidism and a serum TSH level < 10 mIU/L are asymptomatic. Some might have nonspecific symptoms of hypothyroidism, however, such as reduced quality of life, poor cognitive function, and poor memory—symptoms that do not typically correlate with the serum TSH level.

An increase in the dosage of LT4 might be required in pregnancy or when weight gain is significant (> 10% of body weight).

It has been suggested that some elderly people normally have a higher level of serum TSH, and that they might have even a prolonged lifespan.⁵¹ Additionally, it has been shown that, in nonpregnant adult patients with subclinical hypothyroidism and a serum TSH level of 4.5 to 10 mIU/L, treatment with LT4 was not associated with improvement in thyroid-related symptoms or general quality of life.⁵²

Treat, or don't treat, subclinical hypothyroidism?

It is well accepted that the goal of therapy in hypothyroid patients is to normalize the serum TSH level; however, the American Thyroid Association and the American Association of Clinical Endocrinology recommend starting LT4 in patients with a serum TSH level ≥ 10 mIU/L (TABLE 5).^59-62 The principal reason for not treating subclinical hypothyroidism is the lack of benefit in reducing the risk of cardiovascular morbidity and mortality when the TSH level is between 7.5 and 10 mIU/L.⁶²

Continue to: Routine treatment

Routine treatment of patients with a serum TSH level of 4.5 to 10 mIU/L remains controversial. When TSH is 7.0 to 9.9 mIU/L, treatment is recommended for (1) patients < 65 years and (2) for older patients (> 65 years) only when there are convincing hypothyroid symptoms because of concern about unintended overtreatment.

When the TSH level is anywhere above the upper limit of normal to 6.9 mIU/L, treatment is recommended for patients < 65 years old, patients who have a high titer of thyroid peroxidase antibodies, and patients with goiter—but not for patients > 65 years (and, especially, not for octogenarians) because their upper limit of normal could be as high as 6 to 8 mIU/L, especially if they are otherwise healthy.

Treatment should be considered for women with subclinical hypothyroidism who are trying to conceive or experiencing an infertility problem.

For patients with subclinical hypothyroidism who are not being treated, monitor thyroid function every 6 to 12 months by testing TSH and FT4.

CORRESPONDENCE
Thanh D. Hoang, DO, Division of Endocrinology, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda, MD 20889; [email protected]

Overwhelming numbers of early puberty cases among girls have been reported during the pandemic, according a report copublished by the Washington Post and The Fuller Project.

Early puberty is uncommon, affecting about 1 in every 5,000 to 10,000 children, with cases about 10 times higher in girls than boys. But since the pandemic started, doctors and parents around the world have noted a substantial surge in early puberty.

In some cases, girls as young as 5 have begun developing breasts and girls younger than 8 have started menstruation.

“I noticed that quite a few of my [girl patients] got their period after a lockdown,” Adiaha Spinks-Franklin, MD, a pediatrician at Texas Children’s Hospital, Houston, told the news outlets.

The condition, also called precocious puberty, is defined as puberty-related changes earlier than normal or expected, which starts around age 8 for girls and age 9 for boys. It can sometimes be caused by genetic syndromes, central nervous system issues, or tumors on the ovaries, adrenal glands, pituitary gland, or brain.

Pediatricians across the world have reported more precocious puberty cases, the news outlets reported, including in the United States, India, Italy, and Turkey.

A recent study found that more than 300 girls were referred to five pediatric endocrinology centers in Italy between March and September 2020, as opposed to 140 referrals during the same time period in 2019.

In another study, a Turkish pediatric endocrinology clinic reported 58 cases during the first year of the pandemic, as compared with 66 total cases during the 3 previous years.

Early puberty tends to mean there are other mental and physical issues, though in most cases, an exact cause can’t be found. Doctors have tied the current uptick to the stress of the pandemic and lockdowns, including reduced physical activity and increased consumption of unhealthy food, which are things linked to a higher risk of early puberty.

“I think it’s directly related to the amount of stress that the children have gone through,” Vaishakhi Rustagi, MD, a pediatric endocrinologist in Delhi, India, told the news outlets.

In a typical year, Dr. Rustagi sees about 20 patients with early puberty. Since mid-2020, she’s seen more than 300 girls with the condition. Imaging scans and ultrasounds haven’t found tumors, and the cause has been mostly unidentifiable, though Dr. Rustagi attributed it to stress and grief.

“These children have lost family members,” she said.

Early puberty is known to increase depression, eating disorders, substance abuse, and antisocial behavior, the news outlets reported.

The main treatment for the condition, a form of hormone therapy known as gonadotropin-releasing hormone analogue therapy, is known to work very well. But some patients and families may not seek treatment because of a lack of awareness or stigmas that come with menstruation.

A version of this article first appeared on WebMD.com.

Overwhelming numbers of early puberty cases among girls have been reported during the pandemic, according a report copublished by the Washington Post and The Fuller Project.

Early puberty is uncommon, affecting about 1 in every 5,000 to 10,000 children, with cases about 10 times higher in girls than boys. But since the pandemic started, doctors and parents around the world have noted a substantial surge in early puberty.

In some cases, girls as young as 5 have begun developing breasts and girls younger than 8 have started menstruation.

“I noticed that quite a few of my [girl patients] got their period after a lockdown,” Adiaha Spinks-Franklin, MD, a pediatrician at Texas Children’s Hospital, Houston, told the news outlets.

The condition, also called precocious puberty, is defined as puberty-related changes earlier than normal or expected, which starts around age 8 for girls and age 9 for boys. It can sometimes be caused by genetic syndromes, central nervous system issues, or tumors on the ovaries, adrenal glands, pituitary gland, or brain.

Pediatricians across the world have reported more precocious puberty cases, the news outlets reported, including in the United States, India, Italy, and Turkey.

A recent study found that more than 300 girls were referred to five pediatric endocrinology centers in Italy between March and September 2020, as opposed to 140 referrals during the same time period in 2019.

In another study, a Turkish pediatric endocrinology clinic reported 58 cases during the first year of the pandemic, as compared with 66 total cases during the 3 previous years.

Early puberty tends to mean there are other mental and physical issues, though in most cases, an exact cause can’t be found. Doctors have tied the current uptick to the stress of the pandemic and lockdowns, including reduced physical activity and increased consumption of unhealthy food, which are things linked to a higher risk of early puberty.

“I think it’s directly related to the amount of stress that the children have gone through,” Vaishakhi Rustagi, MD, a pediatric endocrinologist in Delhi, India, told the news outlets.

In a typical year, Dr. Rustagi sees about 20 patients with early puberty. Since mid-2020, she’s seen more than 300 girls with the condition. Imaging scans and ultrasounds haven’t found tumors, and the cause has been mostly unidentifiable, though Dr. Rustagi attributed it to stress and grief.

“These children have lost family members,” she said.

Early puberty is known to increase depression, eating disorders, substance abuse, and antisocial behavior, the news outlets reported.

The main treatment for the condition, a form of hormone therapy known as gonadotropin-releasing hormone analogue therapy, is known to work very well. But some patients and families may not seek treatment because of a lack of awareness or stigmas that come with menstruation.

A version of this article first appeared on WebMD.com.

Overwhelming numbers of early puberty cases among girls have been reported during the pandemic, according a report copublished by the Washington Post and The Fuller Project.

Early puberty is uncommon, affecting about 1 in every 5,000 to 10,000 children, with cases about 10 times higher in girls than boys. But since the pandemic started, doctors and parents around the world have noted a substantial surge in early puberty.

In some cases, girls as young as 5 have begun developing breasts and girls younger than 8 have started menstruation.

“I noticed that quite a few of my [girl patients] got their period after a lockdown,” Adiaha Spinks-Franklin, MD, a pediatrician at Texas Children’s Hospital, Houston, told the news outlets.

The condition, also called precocious puberty, is defined as puberty-related changes earlier than normal or expected, which starts around age 8 for girls and age 9 for boys. It can sometimes be caused by genetic syndromes, central nervous system issues, or tumors on the ovaries, adrenal glands, pituitary gland, or brain.

Pediatricians across the world have reported more precocious puberty cases, the news outlets reported, including in the United States, India, Italy, and Turkey.

A recent study found that more than 300 girls were referred to five pediatric endocrinology centers in Italy between March and September 2020, as opposed to 140 referrals during the same time period in 2019.

In another study, a Turkish pediatric endocrinology clinic reported 58 cases during the first year of the pandemic, as compared with 66 total cases during the 3 previous years.

Early puberty tends to mean there are other mental and physical issues, though in most cases, an exact cause can’t be found. Doctors have tied the current uptick to the stress of the pandemic and lockdowns, including reduced physical activity and increased consumption of unhealthy food, which are things linked to a higher risk of early puberty.

“I think it’s directly related to the amount of stress that the children have gone through,” Vaishakhi Rustagi, MD, a pediatric endocrinologist in Delhi, India, told the news outlets.

In a typical year, Dr. Rustagi sees about 20 patients with early puberty. Since mid-2020, she’s seen more than 300 girls with the condition. Imaging scans and ultrasounds haven’t found tumors, and the cause has been mostly unidentifiable, though Dr. Rustagi attributed it to stress and grief.

“These children have lost family members,” she said.

Early puberty is known to increase depression, eating disorders, substance abuse, and antisocial behavior, the news outlets reported.

The main treatment for the condition, a form of hormone therapy known as gonadotropin-releasing hormone analogue therapy, is known to work very well. But some patients and families may not seek treatment because of a lack of awareness or stigmas that come with menstruation.

A version of this article first appeared on WebMD.com.

The Food and Drug Administration has recommended thyroid monitoring for newborns and children through 3 years of age within 3 weeks of receiving injections of iodine-containing contrast media as part of imaging procedures.

A recent FDA review showed that “underactive thyroid or a temporary decrease in thyroid hormone levels were uncommon,” according to an updated Drug Safety Communication issued on March 30, 2022.

However, early monitoring will help identify and treat any thyroid abnormalities as a result of the injections to help prevent potential complications in the future, according to the FDA, as babies and children do not generally show visible signs of thyroid problems and may not do so after an iodinated contrast media (ICM) injection.

ICM have been approved and used for decades to enhance images on x-rays or computed tomography (CT) scans, according to the communication.

The new FDA warning and recommendation for monitoring applies to the prescribing information for the entire class of ICM products. The new communication is an update to the 2015 Drug Safety Communication that advised medical professionals of the potential for underactive thyroid in response to ICM injections in newborns and young children. The update reflects new studies since that time.

The recent research showed that most reported cases of adverse effects were transient subclinical hypothyroidism and did not require treatment, according to the FDA. “The reported rate ranged from 1 percent to 15 percent and tended to be higher in neonates, particularly preterm neonates,” they said. Others at increased risk are those with underlying medical conditions, especially those with cardiac conditions who often require higher doses of contrast during invasive procedures.

In the recent studies, the time from ICM exposure to a diagnosis of thyroid dysfunction ranged from 8.5 to 138 days, but most occurred within 3 weeks, according to the update.

Patients and clinicians can report any adverse events from ICM or other medications to the FDA via FDA MedWatch program.

For more information, read the complete Drug Safety Communication.

The Food and Drug Administration has recommended thyroid monitoring for newborns and children through 3 years of age within 3 weeks of receiving injections of iodine-containing contrast media as part of imaging procedures.

A recent FDA review showed that “underactive thyroid or a temporary decrease in thyroid hormone levels were uncommon,” according to an updated Drug Safety Communication issued on March 30, 2022.

However, early monitoring will help identify and treat any thyroid abnormalities as a result of the injections to help prevent potential complications in the future, according to the FDA, as babies and children do not generally show visible signs of thyroid problems and may not do so after an iodinated contrast media (ICM) injection.

ICM have been approved and used for decades to enhance images on x-rays or computed tomography (CT) scans, according to the communication.

The new FDA warning and recommendation for monitoring applies to the prescribing information for the entire class of ICM products. The new communication is an update to the 2015 Drug Safety Communication that advised medical professionals of the potential for underactive thyroid in response to ICM injections in newborns and young children. The update reflects new studies since that time.

The recent research showed that most reported cases of adverse effects were transient subclinical hypothyroidism and did not require treatment, according to the FDA. “The reported rate ranged from 1 percent to 15 percent and tended to be higher in neonates, particularly preterm neonates,” they said. Others at increased risk are those with underlying medical conditions, especially those with cardiac conditions who often require higher doses of contrast during invasive procedures.

In the recent studies, the time from ICM exposure to a diagnosis of thyroid dysfunction ranged from 8.5 to 138 days, but most occurred within 3 weeks, according to the update.

Patients and clinicians can report any adverse events from ICM or other medications to the FDA via FDA MedWatch program.

For more information, read the complete Drug Safety Communication.

The Food and Drug Administration has recommended thyroid monitoring for newborns and children through 3 years of age within 3 weeks of receiving injections of iodine-containing contrast media as part of imaging procedures.

A recent FDA review showed that “underactive thyroid or a temporary decrease in thyroid hormone levels were uncommon,” according to an updated Drug Safety Communication issued on March 30, 2022.

However, early monitoring will help identify and treat any thyroid abnormalities as a result of the injections to help prevent potential complications in the future, according to the FDA, as babies and children do not generally show visible signs of thyroid problems and may not do so after an iodinated contrast media (ICM) injection.

ICM have been approved and used for decades to enhance images on x-rays or computed tomography (CT) scans, according to the communication.

The new FDA warning and recommendation for monitoring applies to the prescribing information for the entire class of ICM products. The new communication is an update to the 2015 Drug Safety Communication that advised medical professionals of the potential for underactive thyroid in response to ICM injections in newborns and young children. The update reflects new studies since that time.

The recent research showed that most reported cases of adverse effects were transient subclinical hypothyroidism and did not require treatment, according to the FDA. “The reported rate ranged from 1 percent to 15 percent and tended to be higher in neonates, particularly preterm neonates,” they said. Others at increased risk are those with underlying medical conditions, especially those with cardiac conditions who often require higher doses of contrast during invasive procedures.

In the recent studies, the time from ICM exposure to a diagnosis of thyroid dysfunction ranged from 8.5 to 138 days, but most occurred within 3 weeks, according to the update.

Patients and clinicians can report any adverse events from ICM or other medications to the FDA via FDA MedWatch program.

For more information, read the complete Drug Safety Communication.

The widely used antidiabetic drug metformin may cause genital birth defects such as undescended testicles and urethral problems in the male offspring of men who take the medication, researchers have found.

The association appears to involve the effects of metformin on the development of sperm during a critical window prior to conception. Female offspring were not affected. Although previous studies have linked diabetes with fertility problems in men, the latest study is the first to show that these problems can result from treatment rather than the disease itself, according to the researchers, whose findings appear in Annals of Internal Medicine.

“This is the first data to suggest that paternal metformin [use] may be associated with birth defects in children. As such, it would be early to begin to alter clinical practice,” Michael Eisenberg, MD, director of male reproductive medicine and surgery, department of urology, Stanford (Calif.) University, who is a coauthor of the study, said in an interview. “However, if it is confirmed in other populations, then it may begin to enter counseling discussions.”

Dr. Eisenberg added that eating a nutritious diet, exercising, and maintaining a healthy body weight “can improve a man’s health and likely his fertility as well.”

For the new study, Dr. Eisenberg and colleagues analyzed records in a registry of all 1.25 million births that occurred in Denmark between 1997 and 2016. The registry included information on birth defects and parental drug prescriptions.

Offspring were considered exposed to a diabetes drug if a father had filled one or more prescriptions for the medications during the 3 months prior to conception, when the fertilizing sperm would have been produced.

The final analysis included 1,116,779 offspring – all singleton births to women without a history of diabetes or essential hypertension – of whom 7,029 were exposed to diabetes drugs via the father, and 3.3% (n = 36,585) had one or more major birth defects.

Among male offspring whose fathers had taken metformin (n = 1,451), there was a 3.4-fold greater incidence of major genitourinary birth defects, according to the researchers. The study failed to find associations between birth defects and the use of insulin. Although a signal did emerge for sulfonylurea-based drugs, it did not reach statistical significance.

The risk associated with metformin did not appear for men who were prescribed the drug in the year before or after sperm development. Nor was it evident in siblings of the boys with birth defects who were not considered to have been exposed to the medication, the researchers reported.

In an editorial accompanying the journal article, Germaine Buck Louis, PhD, a reproductive and perinatal epidemiologist, wrote: “Given the prevalence of metformin use as first-line therapy for type 2 diabetes, corroboration of these findings is urgently needed.”

Dr. Louis, dean of the College of Health and Human Services at George Mason University, Washington, said a key limitation of the research is the lack of data on how well men in the study adhered to their diabetes treatment. Nevertheless, “clinical guidance is needed to help couples planning pregnancy weigh the risks and benefits of paternal metformin use relative to other medications.”

The researchers received funding from the National Institutes of Health and the Centers for Disease Control and Prevention.

A version of this article first appeared on Medscape.com.

The widely used antidiabetic drug metformin may cause genital birth defects such as undescended testicles and urethral problems in the male offspring of men who take the medication, researchers have found.

The association appears to involve the effects of metformin on the development of sperm during a critical window prior to conception. Female offspring were not affected. Although previous studies have linked diabetes with fertility problems in men, the latest study is the first to show that these problems can result from treatment rather than the disease itself, according to the researchers, whose findings appear in Annals of Internal Medicine.

“This is the first data to suggest that paternal metformin [use] may be associated with birth defects in children. As such, it would be early to begin to alter clinical practice,” Michael Eisenberg, MD, director of male reproductive medicine and surgery, department of urology, Stanford (Calif.) University, who is a coauthor of the study, said in an interview. “However, if it is confirmed in other populations, then it may begin to enter counseling discussions.”

Dr. Eisenberg added that eating a nutritious diet, exercising, and maintaining a healthy body weight “can improve a man’s health and likely his fertility as well.”

For the new study, Dr. Eisenberg and colleagues analyzed records in a registry of all 1.25 million births that occurred in Denmark between 1997 and 2016. The registry included information on birth defects and parental drug prescriptions.

Offspring were considered exposed to a diabetes drug if a father had filled one or more prescriptions for the medications during the 3 months prior to conception, when the fertilizing sperm would have been produced.

The final analysis included 1,116,779 offspring – all singleton births to women without a history of diabetes or essential hypertension – of whom 7,029 were exposed to diabetes drugs via the father, and 3.3% (n = 36,585) had one or more major birth defects.

Among male offspring whose fathers had taken metformin (n = 1,451), there was a 3.4-fold greater incidence of major genitourinary birth defects, according to the researchers. The study failed to find associations between birth defects and the use of insulin. Although a signal did emerge for sulfonylurea-based drugs, it did not reach statistical significance.

The risk associated with metformin did not appear for men who were prescribed the drug in the year before or after sperm development. Nor was it evident in siblings of the boys with birth defects who were not considered to have been exposed to the medication, the researchers reported.

In an editorial accompanying the journal article, Germaine Buck Louis, PhD, a reproductive and perinatal epidemiologist, wrote: “Given the prevalence of metformin use as first-line therapy for type 2 diabetes, corroboration of these findings is urgently needed.”

Dr. Louis, dean of the College of Health and Human Services at George Mason University, Washington, said a key limitation of the research is the lack of data on how well men in the study adhered to their diabetes treatment. Nevertheless, “clinical guidance is needed to help couples planning pregnancy weigh the risks and benefits of paternal metformin use relative to other medications.”

The researchers received funding from the National Institutes of Health and the Centers for Disease Control and Prevention.

A version of this article first appeared on Medscape.com.

The widely used antidiabetic drug metformin may cause genital birth defects such as undescended testicles and urethral problems in the male offspring of men who take the medication, researchers have found.

The association appears to involve the effects of metformin on the development of sperm during a critical window prior to conception. Female offspring were not affected. Although previous studies have linked diabetes with fertility problems in men, the latest study is the first to show that these problems can result from treatment rather than the disease itself, according to the researchers, whose findings appear in Annals of Internal Medicine.

“This is the first data to suggest that paternal metformin [use] may be associated with birth defects in children. As such, it would be early to begin to alter clinical practice,” Michael Eisenberg, MD, director of male reproductive medicine and surgery, department of urology, Stanford (Calif.) University, who is a coauthor of the study, said in an interview. “However, if it is confirmed in other populations, then it may begin to enter counseling discussions.”

Dr. Eisenberg added that eating a nutritious diet, exercising, and maintaining a healthy body weight “can improve a man’s health and likely his fertility as well.”

For the new study, Dr. Eisenberg and colleagues analyzed records in a registry of all 1.25 million births that occurred in Denmark between 1997 and 2016. The registry included information on birth defects and parental drug prescriptions.

Offspring were considered exposed to a diabetes drug if a father had filled one or more prescriptions for the medications during the 3 months prior to conception, when the fertilizing sperm would have been produced.

The final analysis included 1,116,779 offspring – all singleton births to women without a history of diabetes or essential hypertension – of whom 7,029 were exposed to diabetes drugs via the father, and 3.3% (n = 36,585) had one or more major birth defects.

Among male offspring whose fathers had taken metformin (n = 1,451), there was a 3.4-fold greater incidence of major genitourinary birth defects, according to the researchers. The study failed to find associations between birth defects and the use of insulin. Although a signal did emerge for sulfonylurea-based drugs, it did not reach statistical significance.

The risk associated with metformin did not appear for men who were prescribed the drug in the year before or after sperm development. Nor was it evident in siblings of the boys with birth defects who were not considered to have been exposed to the medication, the researchers reported.

In an editorial accompanying the journal article, Germaine Buck Louis, PhD, a reproductive and perinatal epidemiologist, wrote: “Given the prevalence of metformin use as first-line therapy for type 2 diabetes, corroboration of these findings is urgently needed.”

Dr. Louis, dean of the College of Health and Human Services at George Mason University, Washington, said a key limitation of the research is the lack of data on how well men in the study adhered to their diabetes treatment. Nevertheless, “clinical guidance is needed to help couples planning pregnancy weigh the risks and benefits of paternal metformin use relative to other medications.”

The researchers received funding from the National Institutes of Health and the Centers for Disease Control and Prevention.

A version of this article first appeared on Medscape.com.