Thyroid hyperfunction during pregnancy

Evaluation and Management of Thyrotoxicosis During Pregnancy

This review summarizes the diagnosis and management of thyrotoxicosis in pregnancy. The diagnostic clinical and biochemical considerations used to distinguish the various etiologies of hyperthyroidism from appropriate physiologic changes during pregnancy will be outlined. Finally, the review will discuss the risks and benefits of available options for the treatment of thyrotoxicosis during pregnancy, to mitigate the risks of fetal hyperthyroidism.

Maternal subclinical hyperthyroidism and adverse pregnancy outcomes considering the iodine status: Tehran thyroid and pregnancy study

BACKGROUND

Unlike overt thyroid diseases, the impacts of subclinical thyroid dysfunction, especially subclinical hyperthyroidism (SH), on adverse pregnancy outcomes are inconclusive.

OBJECTIVE

We aimed to investigate the effect of maternal SH on adverse maternal and neonatal outcomes based on urinary iodine concentration (UIC).

METHODS

A secondary analysis was run on data collected in the Tehran Thyroid and Pregnancy study (TTPs). We used the data of 131 women with SH and 1650 cases of euthyroid. Serum levels of thyroid-stimulating hormone (TSH), thyroxine (T4), free thyroxine index (FT4I), and thyroid peroxidase antibody (TPOAb) were assessed at the first prenatal visit. A generalized linear regression model was applied to identify the effect of SH on the pregnancy outcomes based on UIC, and the effects were estimated with a 95% confidence interval.

RESULTS

Preterm delivery was observed in 12.3% of women with SH and 6.7% of those with euthyroid (P = 0.03). Women with TSH< 0.3 mIU/L had a higher odds of preterm delivery than those with TSH≥ 0.3 regardless of urine iodine cut-off [OR= 2.27; 95% CI: (1.15, 4.48), p = 0.02]. Among those with UIC levels≥ 150 μg/L, the odds ratio of preterm delivery was 4.61 folds higher in the SH group compared to those with euthyroid [95%CI: (1.36, 15.71), p = 0.01)]. No significant difference between these two study groups was found in Neonatal Intensive Care Unit admission. Moreover, the results revealed no statistically significant difference in the means of neonatal anthropometric parameters in the SH and euthyroid groups in none of the subgroups of UIC (<150 or ≥150 µg/l).

CONCLUSIONS

According to our results, maternal SH appears to be a risk factor for preterm delivery. This effect is more pronounced in women with higher UIC than those with lower UIC.

Maternal Subclinical Hyperthyroidism and Adverse Pregnancy Outcomes: A Systematic Review and Meta-analysis of Observational Studies

CONTEXT

Findings from studies evaluating adverse pregnancy outcomes in pregnant women with subclinical hyperthyroidism are conflicting and inconclusive.

OBJECTIVES

In this systematic review and meta-analysis, our aim was to evaluate the pooled odds ratio (OR) of adverse pregnancy outcomes in women with subclinical hyperthyroidism, compared to euthyroid women.

DATA SOURCES

Scopus, PubMed (including Medline), and Web of Science databases were systemically searched for regaining published studies to January 2022 examining adverse pregnancy outcomes in women with subclinical hyperthyroidism.

STUDY SELECTION

Outcomes of interest were classified into seven composite outcomes, including hypertensive disorders, preterm delivery, macrosomia/large for gestational age (LGA), pregnancy loss, adverse maternal outcomes, adverse neonatal outcomes, and adverse fetal outcomes.

DATA EXTRACTION

In this meta-analysis, both fixed and random effect models were used. Publication bias was also evaluated by Egger test and the funnel plot, and the trim and fill method was conducted in case of a significant result, to adjust the bias.

RESULTS

Of 202 records retrieved through searching databases, 11 studies were selected for the final analyses. There were no significant differences in pooled ORs of hypertensive disorders, preterm delivery, macrosomia/LGA, and pregnancy loss in pregnant women with subclinical hyperthyroidism, compared to the euthyroid controls. The pooled OR of adverse maternal, neonatal, and fetal outcomes in pregnant women with subclinical hyperthyroidism was not statistically significantly different from that of the euthyroid control group.

CONCLUSIONS

The current meta-analysis demonstrated that subclinical hyperthyroidism in pregnancy is not related with adverse maternal and fetal outcomes. Therefore, clinicians should be avoided unnecessary treatments for pregnant women with subclinical hyperthyroidism.

Links between Thyroid Disorders and Glucose Homeostasis

Thyroid disorders and diabetes mellitus often coexist and are closely related. Several studies have shown a higher prevalence of thyroid disorders in patients with diabetes mellitus and vice versa. Thyroid hormone affects glucose homeostasis by impacting pancreatic β-cell development and glucose metabolism through several organs such as the liver, gastrointestinal tract, pancreas, adipose tissue, skeletal muscles, and the central nervous system. The present review discusses the effect of thyroid hormone on glucose homeostasis. We also review the relationship between thyroid disease and diabetes mellitus: type 1, type 2, and gestational diabetes, as well as guidelines for screening thyroid function with each disorder. Finally, we provide an overview of the effects of antidiabetic drugs on thyroid hormone and thyroid disorders.

Subclinical thyroid diseases and isolated hypothyroxinemia during pregnancy

Thyroid diseases in pregnancy are common. While data on management of overt diseases are clear, there is no consensus regarding subclinical thyroid disease. Many studies have tried to clarify the impact of subclinical thyroid disease on pregnancy outcomes without reaching universal conclusions. As several studies are present in literature, but no univocal indication is present to manage each condition, the present review tries to summarize the recent indications for such disease. The most updated guidelines are 2017 American thyroid association for thyroid disease during pregnancy, which at present represent the most accurate and reliable guide. Subclinical hyperthyroidism during pregnancy has not been associated with adverse outcomes and only needs follow up. Subclinical hypothyroidism is associated with adverse obstetric and offspring outcomes. At present thyroxine treatment is recommended in selected cases, as beneficial effects are not clear for all these patients. Data regarding the association between isolated hypothyroxinemia and adverse maternofetal outcome are controversial but treatment is not indicated. Autoimmune thyroid disease represents the main thyroid risk factor for adverse pregnancy outcomes. If patients have normal TSH values, treatment is not indicated. A possible thyroxine treatment can be evaluated on a case-by-case basis in euthyroid patients with history of abortion/infertility. In the last years, risks of subclinical thyroid dysfunction on the outcome of gestation and new-born have been scaled back. Further prospective studies are necessary to better understand thyroid dysfunction in pregnancy to perfectly target treatment in appropriate settings.

Definition and Multiple Factors of Recurrent Spontaneous Abortion

Recurrent spontaneous abortion (RSA) is usually defined as three or more spontaneous abortions prior to 20-28 weeks gestation. RSA affects approximately 2-5% of all women of childbearing age, and it brings tremendous psychological and psychiatric trauma to the women and also results in economic burden. The causes could be female age, anatomical and chromosomal abnormalities, genetic, endocrinological, placental anomalies, infection, smoking and alcohol consumption, psychological factor, exposure to environmental factors such as heavy metal, environment pollution, and radiation.

Safety of antithyroid drugs in pregnancy: update and therapy implications

Introduction: The thionamide antithyroid drugs, methimazole (MMI), its pro-drug derivative carbimazole (CMZ), and propylthiouracil (PTU) are the mainstay of treatment for hyperthyroidism in pregnancy. However, antithyroid drugs carry risks of adverse effects that can affect fetal and maternal well-being.Areas covered: This review provides an update on the safety of antithyroid drugs in pregnancy, focusing on the most serious concerns of severe liver disease and congenital anomalies.Expert opinion: PTU-induced liver disease is uncommon but can run a catastrophic course in pregnancy with a risk of liver failure and threats to maternal or fetal survival. Acute pancreatitis is a relatively rare occurrence that has been linked to thionamide use in a handful of reports in non-pregnant individuals. Observational studies on the risk of birth defects with antithyroid drug exposure in pregnancy overall show an increase in birth defect risk with exposure to CMZ/MMI, and to a lesser extent, PTU. Further studies are required to determine whether the currently recommended approach of switching between thionamide drugs in pregnancy improves outcomes. Ultimately, a preventative strategy of offering definitive therapy to hyperthyroid women of childbearing potential offers the best approach to truly reduce the risks of antithyroid drug adverse effects in pregnancy.

Assessment of thyroid functions and thyroid volume in normal pregnant Egyptian females

The normal range of thyroid functions during pregnancy differs between ethnic groups. This study assessed the thyroid functions in normal pregnant Egyptian females. Thyroid peroxidase antibodies (TPO Abs) and thyroid volume were also assessed. The study included 150 normal pregnant Egyptian females, recruited from Cairo University Hospital Antenatal Care Clinic (50 in each trimester), with 40 age-matched non-pregnant females, as a control group. Serum thyroid stimulating hormone (TSH) and TPO Abs were measured. Thyroid volume was assessed by ultrasonography. TSH ranges were 0.21-1.7, 0.52-3.2 and 0.72-2.6 mIU/L during first, second and third trimesters, respectively. The mean TSH level in pregnant females was significantly lower than that of non-pregnant women (1.2 ± 0.7 vs 2.7 ± 0.9 mIU/L, p < .001). TPO Abs were significantly higher in the first trimester compared to both second and third trimesters (p < .001 for both). Thyroid volume of pregnant females was non-significantly higher than that of non-pregnant control subjects (p = .126). A significant positive correlation was found between thyroid volume and body mass index in pregnant females (p < 0.001). Our study established trimester-specific reference ranges for thyroid functions in normal pregnant Egyptian females. A larger population-based study would help to confirm those ranges. Thyroid volume was non-significantly higher than that of non-pregnant control subjects.

Hyperthyroidism and Pregnancy

Clinical hyperthyroidism affects 0.1% to 0.4% of pregnancies. Gestational thyrotoxicosis is due to homology of the structure of TSH and HCG, which weakly stimulates the TSH receptor. Graves' disease (GD) most commonly causes clinically significant hyperthyroidism. Given concerns for teratogenicity from antithyroid drugs, these may be discontinued in low-risk GD patients. High-risk patients are treated with propylthiouracil in the first trimester then may transition to methimazole. Surgery is reserved for special circumstances; radioactive iodine is contraindicated. In late pregnancy, GD may remit; postpartum relapse is common. Measurement of serum thyrotropin receptor antibodies identifies pregnancies at-risk for fetal and neonatal hyperthyroidism.

Acute myocardial infarction in pregnancy: spasm caused by hyperthyroidism?

We present a 26-year-old woman with ST-segment elevation myocardial infarction in the 14th week of pregnancy. Coronary angiography revealed no abnormalities in the coronary arteries. She had no history of coronary risk factors such as smoking, diabetes mellitus, hypertension, or dyslipidemia. Although we do not have direct evidence of coronary spasm in this patient, several factors suggest that coronary spasm is the most likely cause of myocardial infarction. We suspect that hyperthyroidism may have played an important role in coronary spasm in this patient. Early use of coronary angiography is helpful to identify the types of coronary artery lesions.

Maternal Thyroid Function During Pregnancy or Neonatal Thyroid Function and Attention Deficit Hyperactivity Disorder: A Systematic Review

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is the most common neurobehavioral disorder in children, yet its etiology is poorly understood. Early thyroid hormone disruption may contribute to the development of ADHD. Disrupted maternal thyroid hormone function has been associated with adverse neurodevelopmental outcomes in children. Among newborns, early-treated congenital hypothyroidism has been consistently associated with later cognitive deficits.

METHODS

We systematically reviewed literature on the association between maternal or neonatal thyroid hormones and ADHD diagnosis or symptoms. We searched Embase, Pubmed, Cinahl, PsycInfo, ERIC, Medline, Scopus, and Web of Science for articles published or available ahead of print as of April 2018.

RESULTS

We identified 28 eligible articles: 16 studies of maternal thyroid hormones, seven studies of early-treated congenital hypothyroidism, and five studies of neonatal thyroid hormones. The studies provide moderate evidence for an association between maternal thyroid hormone levels and offspring ADHD, some evidence for an association between early-treated congenital hypothyroidism and ADHD, and little evidence for an association between neonatal thyroid hormone levels and later ADHD.

CONCLUSIONS

The reviewed articles suggest an association between maternal thyroid function and ADHD, and possibly between early-treated congenital hypothyroidism and ADHD. Study limitations, however, weaken the conclusions in our systematic review, underlining the need for more research. Importantly, there was much variation in the measurement of thyroid hormone function and of ADHD symptoms. Recommendations for future research include using population-based designs, attending to measurement issues for thyroid hormones and ADHD, considering biologically relevant covariates (e.g., iodine intake), and assessing nonlinear dose-responses.

Secondary and tertiary preventions of thyroid disease

INTRODUCTION

Secondary and tertiary preventions are concerned with the recognition of the disease process in a very early stage and delay in progression to complete disease and minimization of complications and the impact of illness.

METHODS

All articles related to secondary and tertiary prevention of thyroid diseases were reviewed. Using related key words, articles published between 2001 and 2015 were evaluated, categorized, and analyzed.

RESULTS

In secondary prevention, congenital hypothyroidism and subclinical hypo and hyperthyroidism are equally important. Routine screening of patients with multinodular goiter by either ultrasonography or calcitonin is a controversial issue, while calcitonin assessments in medullary cancer and RET in family members are recommended. Screening of thyroid disease in pregnancy is limited to those with risk factors. Views regarding the importance of thyroid autoimmunity in secondary prevention are also presented. In tertiary prevention, prescribing excessive doses of levothyroxine, in the elderly in particular and appropriate care of all patients to avoid progression and complications are the key issues.

CONCLUSION

Optimization of management of thyroid diseases requires timely screening, prevention of progression to more sever disease, optimal medical care, and avoidance of iatrogenic conditions.

Antithyroid drug therapy in pregnancy: a review of guideline recommendations

The antithyroid drugs, Carbimazole, Methimazole, and Propylthiouracil remain the mainstay of Graves' disease management in pregnancy. A series of Clinical Practice Guidelines aimed at optimising fetal and maternal outcomes in women with Graves' disease have been published in recent years. Areas covered: This review examines existing guideline recommendations on antithyroid drug management of Graves' disease in pregnancy. Expert commentary: Recent guidelines have been shaped by expanding knowledge of the adverse effect profiles of antithyroid drugs on the developing fetus. A core management strategy is to limit fetal exposure to excess thyroid hormones and to curtail adverse drug effects through effective preconception and peri-conception management. Propylthiouracil is the recommended treatment in the first trimester of pregnancy but there is uncertainty regarding antithyroid drug choices in women who continue to require treatment in later pregnancy. Further studies are needed to fully evaluate the risks of congenital anomalies following intrauterine thionamide exposure.

2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum

BACKGROUND

Thyroid disease in pregnancy is a common clinical problem. Since the guidelines for the management of these disorders by the American Thyroid Association (ATA) were first published in 2011, significant clinical and scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid disease in women during pregnancy, preconception, and the postpartum period.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations. The guideline task force had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid disease in pregnancy include recommendations regarding the interpretation of thyroid function tests in pregnancy, iodine nutrition, thyroid autoantibodies and pregnancy complications, thyroid considerations in infertile women, hypothyroidism in pregnancy, thyrotoxicosis in pregnancy, thyroid nodules and cancer in pregnant women, fetal and neonatal considerations, thyroid disease and lactation, screening for thyroid dysfunction in pregnancy, and directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid disease in pregnant and postpartum women. While all care must be individualized, such recommendations provide, in our opinion, optimal care paradigms for patients with these disorders.

Effects of In Utero Thyroxine Exposure on Murine Cranial Suture Growth

Large scale surveillance studies, case studies, as well as cohort studies have identified the influence of thyroid hormones on calvarial growth and development. Surveillance data suggests maternal thyroid disorders (hyperthyroidism, hypothyroidism with pharmacological replacement, and Maternal Graves Disease) are linked to as much as a 2.5 fold increased risk for craniosynostosis. Craniosynostosis is the premature fusion of one or more calvarial growth sites (sutures) prior to the completion of brain expansion. Thyroid hormones maintain proper bone mineral densities by interacting with growth hormone and aiding in the regulation of insulin like growth factors (IGFs). Disruption of this hormonal control of bone physiology may lead to altered bone dynamics thereby increasing the risk for craniosynostosis. In order to elucidate the effect of exogenous thyroxine exposure on cranial suture growth and morphology, wild type C57BL6 mouse litters were exposed to thyroxine in utero (control = no treatment; low ~167 ng per day; high ~667 ng per day). Thyroxine exposed mice demonstrated craniofacial dysmorphology (brachycranic). High dose exposed mice showed diminished area of the coronal and widening of the sagittal sutures indicative of premature fusion and compensatory growth. Presence of thyroid receptors was confirmed for the murine cranial suture and markers of proliferation and osteogenesis were increased in sutures from exposed mice. Increased Htra1 and Igf1 gene expression were found in sutures from high dose exposed individuals. Pathways related to the HTRA1/IGF axis, specifically Akt and Wnt, demonstrated evidence of increased activity. Overall our data suggest that maternal exogenous thyroxine exposure can drive calvarial growth alterations and altered suture morphology.

A rare case of gestational thyrotoxicosis as a cause of acute myocardial infarction

Angina pectoris in pregnancy is unusual and Prinzmetal's angina is much rarer. It accounts for 2% of all cases of angina. It is caused by vasospasm, but the mechanism of spasm is unknown but has been linked with hyperthyroidism in some studies. Patients with thyrotoxicosis-induced acute myocardial infarction are unusual and almost all reported cases have been associated with Graves' disease. Human chorionic gonadotropin hormone-induced hyperthyroidism occurs in about 1.4% of pregnant women, mostly when hCG levels are above 70-80 000 IU/L. Gestational transient thyrotoxicosis is transient and generally resolves spontaneously in the latter half of pregnancy, and specific antithyroid treatment is not required. Treatment with calcium channel blockers or nitrates reduces spasm in most of these patients. Overall, the prognosis for hyperthyroidism-associated coronary vasospasm is good. We describe a very rare case of an acute myocardial infarction in a 27-year-old female, at 9 weeks of gestation due to right coronary artery spasm secondary to gestational hyperthyroidism with free thyroxine of 7.7 ng/dL and TSH <0.07 IU/L.

LEARNING POINTS

AMI and cardiac arrest due to GTT despite optimal medical therapy is extremely rare.Gestational hyperthyroidism should be considered in pregnant patients presenting with ACS-like symptoms especially in the setting of hyperemesis gravidarum.Our case highlights the need for increased awareness of general medical community that GTT can lead to significant cardiac events. Novel methods of controlling GTT as well as medical interventions like ICD need further study.

Current challenges in the pharmacological management of thyroid dysfunction in pregnancy

INTRODUCTION

Thyroid dysfunction is common in pregnancy and has adverse fetal and maternal health consequences. A number of challenges in the management of gestational thyroid dysfunction remain unresolved including uncertainties in optimal thresholds for correction of hypothyroidism and strategies for pharmacological management of hyperthyroidism. Areas covered: We addressed key challenges and areas of uncertainty in the management of thyroid dysfunction in pregnancy. Expert commentary: Gestational thyroid hormone reference intervals vary according to population ethnicity, iodine nutrition, and assay method and each population should derive trimester specific reference intervals for use in pregnancy. Subclinical hypothyroidism and isolated hypothyroxinaemia are common in pregnancy but there is no consensus on the benefits of correcting these conditions. Although observational studies show potential benefits of levothyroxine on child neurocognitive function these benefits are have not been supported by two controlled trials. Carbimazole should be avoided in the first trimester of pregnancy due to risk of congenital anomalies but recent studies would suggest that this risk is present to a lesser magnitude with propylthiouracil. Current international guidelines recommend the use of propylthiouracil in the first trimester and switching to carbimazole for the remainder of pregnancy but the benefits and practicalities of this approach is unproven.

Update on the Management of Thyroid Disease during Pregnancy

Thyroid dysfunction during pregnancy can result in serious complications for both the mother and infant; however, these complications can be prevented by optimal treatment of maternal overt thyroid dysfunction. Although several studies have demonstrated that maternal subclinical hypothyroidism is associated with obstetric complications and neurocognitive impairments in offspring, there is limited evidence that levothyroxine treatment can improve these complications. Therefore, most professional societies do not recommend universal screening for thyroid dysfunction during pregnancy, and instead recommend a case-finding approach in which only high-risk women are tested. However, recent studies have estimated that targeted thyroid function testing misses approximately 30% to 55% of hypothyroidism cases in pregnant women, and some associations and researchers have recommended universal screening of pregnant women to facilitate the early detection and treatment of overt hypothyroidism. This review summarizes recent data on thyroid function test changes, thyroid functional disorder management, and thyroid screening during pregnancy.

Endocrine dysfunction and recurrent spontaneous abortion: An overview

Miscarriage is the spontaneous loss of a fetus before it is viable, occurring at a rate of 15–20%. Recurrent spontaneous abortion (RSA) or habitual miscarriage is defined as repeated occurrence of 3 or more miscarriages before 20^th week of gestation accounting for the most common complication of early pregnancy in humans. Various etiological factors responsible for recurrent miscarriage are anatomical, genetical, endocrinological, immunological, and infectious. The endocrinological abnormalities may be polycystic ovarian syndrome, hyperprolactinemia, luteal phase defect, thyroid dysfunction, diabetes, or hyperandrogenism contributing to recurrent pregnancy loss. In the present article, the role of endocrinological disorders in patients with RSA has been reviewed. The article search was done using electronic databases, Google scholarly articles, and PubMed based on different key words. We have further combined the searches and made grouping as per various endocrine abnormalities, which might be responsible to cause spontaneous loss of fetus.

Gestational thyrotoxicosis, antithyroid drug use and neonatal outcomes within an integrated healthcare delivery system

BACKGROUND

Increasing attention has focused on the prevalence and outcomes of hyperthyroidism in pregnancy, given concerns for hepatotoxicity and embryopathy associated with antithyroid drugs (ATDs).

METHODS

In an integrated health care delivery system, we examined the prevalence of thyrotoxicosis and gestational ATD use (propylthiouracil [PTU] or methimazole [MMI]) in women with delivered pregnancies from 1996 to 2010. Birth outcomes were compared among all infants and those born to mothers with diagnosed thyrotoxicosis or ATD therapy during gestation, with examination of ATD-associated hepatotoxicity and congenital malformations in the latter subgroups.

RESULTS

Among 453,586 mother-infant pairs (maternal age 29.7±6.0 years, 57.1% nonwhite), 3.77 per 1000 women had diagnosed thyrotoxicosis and 1.29 per 1000 had gestational ATD exposure (86.5% PTU, 5.1% MMI, 8.4% both). Maternal PTU-associated hepatotoxicity occurred with a frequency of 1.80 per 1000 pregnancies. Infants of mothers with diagnosed thyrotoxicosis (odds ratio [OR] 1.28, 95% confidence interval [CI 1.05-1.55]) or gestational ATD use (OR 1.31 [1.00-1.72]) had an increased risk of preterm birth compared to those born to mothers without thyrotoxicosis or ATD. The risk of neonatal intensive care unit (NICU) admission was also higher with maternal thyrotoxicosis (OR 1.30 [1.07-1.59]) and ATD exposure (OR 1.64 [CI 1.26-2.13]), adjusting for prematurity. Congenital malformation rates were low and similar among infants born to mothers with thyrotoxicosis or ATD exposure (30-44 per 1000 infants).

CONCLUSIONS

Gestational ATD exposure occurred in 1.29 per 1000 mother-infant pairs while a much larger number had maternal diagnosed thyrotoxicosis but no drug exposure during pregnancy. Infants of mothers with gestational ATD use or diagnosed thyrotoxicosis were more likely to be preterm and admitted to the NICU. The rates of congenital malformation were low for mothers diagnosed with thyrotoxicosis and did not differ by ATD use. Among women with gestational PTU therapy, the frequency of PTU-associated hepatotoxicity was 1.8 per 1000 delivered pregnancies. These findings from a large, population-based cohort provide generalizable estimates of maternal and infant risks associated with maternal thyrotoxicosis and related pharmacotherapy.

Fetal right-ventricular hypertrophy with pericardial effusion and maternal untreated hyperthyroidism

Uncontrolled/untreated maternal hyperthyroidism has been associated with fetal tachycardia. We report a case of right-ventricular (RV) hypertrophy with pericardial effusion related to untreated maternal Graves' disease. A 33-year-old G4P1021 woman with uncontrolled Graves' disease presented at 29 weeks gestation with abdominal pain and vaginal bleeding. Fetal echocardiogram showed severe RV hypertrophy and a pericardial effusion. The infant was born prematurely, and initial transthoracic echocardiogram showed severe RV hypertrophy and a small pericardial effusion. The infant had clinical findings consistent with congenital thyrotoxicosis and was treated for this. Follow-up imaging at 4 weeks showed improvement of the cardiac hypertrophy and pericardial effusion. This article describes the presentation of fetal RV hypertrophy with congenital thyrotoxicosis and underscores the importance of screening for this prenatally in mothers with uncontrolled or untreated hyperthyroidism.

Thyroid disorders during pregnancy

Thyroid disorders are common in pregnancy and in nonpregnant women of childbearing age, but can be missed because of nonspecific symptoms and normal changes in thyroid gland physiology during pregnancy. The prevalence of overt hyperthyroidism complicating pregnancy has been reported to range between 0.4% and 1.7%, and an estimated 2% to 3% of women are hypothyroid during pregnancy. Abnormalities in maternal thyroid function are associated with complications during pregnancy, and may affect maternal and fetal outcomes. Thus it is important to identify thyroid disorders before pregnancy or early in pregnancy so that appropriate treatment can be initiated.

Prevalence of overt and subclinical thyroid dysfunction among pregnant women and its effect on maternal and fetal outcome

AIM

To determine the current prevalence of thyroid dysfunction in normal pregnant women and to study the impact of thyroid dysfunction on maternal and fetal outcome.

METHODS

400 pregnant women between 13 and 26 weeks of gestation were registered for the study. Apart from routine obstetrical investigations, TSH tests were done. Free T4 and anti-TPO antibody tests were done in patients with deranged TSH. Patients were followed up till delivery. Their obstetrical and perinatal outcomes were noted.

RESULTS

The prevalence of hypothyroidism and hyperthyroidism was 12 and 1.25 %, respectively. Adverse maternal effects in overt hypothyroidism included preeclampsia (16.6 vs. 7.8 %) and placental abruption (16.6 vs. 0.8 %). Subclinical hypothyroidism was associated with preeclampsia (22.3 vs. 7.8 %) as compared to the euthyroid patients. Adverse fetal outcomes in overt hypothyroidism included spontaneous abortion (16.6 vs. 2.39 %), preterm birth (33.3 vs. 5.8 %), low birth weight (50 vs. 12.11 %), intrauterine growth retardation (25 vs. 4.9 %), and fetal death (16.6 vs. 1.7 %) as compared to the euthyroid women. Adverse fetal outcomes in subclinical hypothyroidism included spontaneous abortion (5.5 vs. 2.39 %), preterm delivery (11.2 vs. 5.8 %), low birth weight (25 vs. 12.11 %), and intrauterine growth retardation (8.4 vs. 4.9 %) as compared to the euthyroid women.

CONCLUSIONS

The prevalence of thyroid disorders was high in our study with associated adverse maternal and fetal outcomes. Routine screening of thyroid dysfunction is recommended to prevent adverse fetal and maternal outcome.

Management of hyperthyroidism in pregnancy: comparison of recommendations of american thyroid association and endocrine society

Appropriate diagnosis and treatment of hyperthyroidism during pregnancy are of outmost importance, because hyperthyroidism has major adverse impact on both mother and fetus. Since data on the management of thyroid dysfunction during pregnancy is rapidly evolving, two guidelines have been developed by the American Thyroid Association and the Endocrine society in the last 2 years. We compare here the recommendations of these two guidelines regarding management of hyperthyroidism during pregnancy. The comparison reveals no disagreement or controversy on the various aspects of diagnosis and treatment of hyperthyroidism during pregnancy between the two guidelines. Propylthiouracil has been considered as the first-line drug for treatment of hyperthyroidism in the first trimester of pregnancy. In the second trimester, consideration should be given to switching to methimazole for the rest of pregnancy. Methimazole is also the drug of choice in lactating hyperthyroid women.

Screening for maternal thyroid dysfunction in pregnancy: a review of the clinical evidence and current guidelines

Observational studies have demonstrated that maternal thyroid dysfunction and thyroid autoimmunity in pregnancy may be associated with adverse obstetric and fetal outcomes. Treatment of overt maternal hyperthyroidism and overt hypothyroidism clearly improves outcomes. To date there is limited evidence that levothyroxine treatment of pregnant women with subclinical hypothyroidism, isolated hypothyroxinemia, or thyroid autoimmunity is beneficial. Therefore, there is ongoing debate regarding the need for universal screening for thyroid dysfunction during pregnancy. Current guidelines differ; some recommend an aggressive case-finding approach, whereas others advocate testing only symptomatic women or those with a personal history of thyroid disease or other associated medical conditions.

Effectiveness of preoperative plasmapheresis in a pregnancy complicated by hyperthyroidism and anti-thyroid drug-associated angioedema

Hyperthyroidism is not a rare entity in pregnancy and 85% of these cases attributed to Graves' disease (GD). There is no therapeutic modality for GD considered as totally safe in pregnancy. Fetal and neonatal risks of maternal hyperthyroid disease are related to the hyperthyroidism itself and/or to the medical treatment of the disease. There are no data supporting an association between congenital anomalies in the fetus and propylthiouracil (PTU). Hepatotoxicity, cytopenias--especially agranulocytosis and quite rarely, angioedema, may be seen as side effects of PTU. In this case report, we examine an instance of Graves' hyperthyroidism diagnosed during pregnancy. In this case, a serious side effect during anti-thyroid drug usage was encountered, eventually resulting in surgery in the second trimester. This intervention was assisted by the use of plasmapheresis to obtain rapid normalization of serum thyroid hormone levels.

Prevalance of gestational diabetes mellitus in patients with gestational transient thyrotoxicosis

OBJECTIVE

To investigate prevalence of gestational diabetes mellitus (GDM) in patients with gestational transient thyroxicosis (GTT).

METHODS

Fifty two patients with GTT and 100 age matched healthy pregnant women were included. Fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), LDL-cholesterol, HDL-cholesterol, triglyceride, thyrotrophin (TSH) and thyroid hormones were measured at thyrotoxic state in GTT patients and at 6-12th weeks of pregnancy in control group. Oral glucose tolerance test (OGTT) with 100 g glucose was performed and laboratory parameters were re-evaluated at 24-28th weeks of pregnancy in all subjects.

RESULTS

Mean age of patients with GTT was 28.46 ± 5.45 and control group was 27.78 ± 3.75(p = 0.085). Patients with GTT had significantly higher HbA1c, LDL-cholesterol and HDL-cholesterol at 6-12th weeks of pregnancy (p < 0.01, p < 0.01 and p = 0.034, respectively). TSH was negatively correlated with HbA1c and LDL-cholesterol in thyrotoxic state in GTT patients (r = -0.393, p < 0.001 and r = -0.293, p < 0.001, respectively). OGTT showed GDM in 7 (13.5%) GTT patients and 4 (4%) healthy pregnants (p = 0.047). HbA1c, LDL-cholesterol and HDL-cholesterol were higher in GTT patients compared to healthy pregnants also at 24-28th weeks of pregnancy (p < 0.001, p < 0.001 and p = 0.024).

CONCLUSION

Although GTT is known to be a transient state that can resolve spontaneously, it might have negative effect on carbohydrate metabolism like other causes of hyperthyroidism.

The interplay of Graves' disease and twin molar pregnancy

Twin molar pregnancy with coexistent viable fetus in a patient with Graves' disease is a rare entity. The patient is a 37-year-old woman who was hospitalised owing to persistent vomiting and vaginal bleeding. The pregnancy test was positive and the pelvic ultrasound disclosed twin gestation of complete mole and a coexistent viable 12-week fetus. β-Human chorionic gonadotropin (β-HCG) and free thyroid hormones were both elevated. The patient was also a diagnosed case of Graves' disease prior to this pregnancy. Given the risks for perinatal complications, the patient was offered early termination of pregnancy. She, however, decided to continue her pregnancy and control the hyperthyroidism with an antithyroid drug (ATD). A week after her discharge from the hospital, she had spontaneous abortion and the histopathology of the abortus revealed complete hydatidiform mole and a 13-week fetus.

Embryonic exposure to propylthiouracil disrupts left-right patterning in Xenopus embryos

Antithyroid medications are the preferred therapy for the treatment of Graves' disease during pregnancy. Propylthiouracil (PTU) is favored over methimazole (MMI) due to potential teratogenic concerns with MMI. This study was to determine the teratogenic potential of MMI and PTU using a validated Xenopus tropicalis embryo model. Embryos were exposed to 1 mM PTU (EC(50)=0.88 mM), 1 mM MMI, or vehicle control (water) from stages 2 to 45. Treated embryos were examined for gross morphological defects, ciliary function, and gene expression by in situ hybridization. Exposure to PTU, but not MMI, led to cardiac and gut looping defects and shortening along the anterior-posterior axis. PTU exposure during gastrulation (stage 8-12.5) was identified as the critical period of exposure leading to left-right (LR) patterning defects. Abnormal cilia polarization, abnormal cilia-driven leftward flow at the gastrocoel roof plate (GRP), and aberrant expression of both Coco and Pitx2c were associated with abnormal LR symmetry observed following PTU exposure. PTU is teratogenic during late blastula, gastrulation, and neurulation; whereas MMI is not. PTU alters ciliary-driven flow and disrupts the normal genetic program involved in LR axis determination. These studies have important implications for women taking PTU during early pregnancy.

Thyroid disorders in pregnancy

The thyroid gland is substantially challenged during pregnancy. Total T(3) and T(4) levels increase by 50% during pregnancy owing to a 50% increase in thyroxine-binding globulin levels. Serum TSH levels decrease in the first trimester and increase in the second and third trimesters; however, not to prepregnancy levels. Hypothyroidism is present in up to 3% of all pregnant women. Subclinical hypothyroidism during pregnancy is associated with an increased rate of miscarriage and preterm delivery, and a decrease in the IQ of the child. Overt hyperthyroidism is present in less than 1% of pregnant women but is linked to increased rates of miscarriage, preterm delivery and maternal congestive heart failure. In women who are euthyroid, thyroid autoantibodies are associated with an increased risk of spontaneous miscarriage and preterm delivery. Postpartum thyroiditis occurs in 5.4% of all women following pregnancy; moreover, 50% of women who are euthyroid in the first trimester of pregnancy but test positive for thyroid autoantibodies will develop postpartum thyroiditis. The need for the essential nutrient iodine increases during pregnancy and in women who are breastfeeding, and the effect of treatment of mild iodine deficiency on maternal and fetal outcomes is consequently being evaluated in a prospective study. The debate regarding the pros and cons of universal screening for thyroid disease during pregnancy is ongoing.

Management of thyroid dysfunction during pregnancy and postpartum: an Endocrine Society clinical practice guideline

OBJECTIVE

The aim was to update the guidelines for the management of thyroid dysfunction during pregnancy and postpartum published previously in 2007. A summary of changes between the 2007 and 2012 version is identified in the Supplemental Data (published on The Endocrine Society's Journals Online web site at http://jcem.endojournals.org).

EVIDENCE

This evidence-based guideline was developed according to the U.S. Preventive Service Task Force, grading items level A, B, C, D, or I, on the basis of the strength of evidence and magnitude of net benefit (benefits minus harms) as well as the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence.

CONSENSUS PROCESS

The guideline was developed through a series of e-mails, conference calls, and one face-to-face meeting. An initial draft was prepared by the Task Force, with the help of a medical writer, and reviewed and commented on by members of The Endocrine Society, Asia and Oceania Thyroid Association, and the Latin American Thyroid Society. A second draft was reviewed and approved by The Endocrine Society Council. At each stage of review, the Task Force received written comments and incorporated substantive changes.

CONCLUSIONS

Practice guidelines are presented for diagnosis and treatment of patients with thyroid-related medical issues just before and during pregnancy and in the postpartum interval. These include evidence-based approaches to assessing the cause of the condition, treating it, and managing hypothyroidism, hyperthyroidism, gestational hyperthyroidism, thyroid autoimmunity, thyroid tumors, iodine nutrition, postpartum thyroiditis, and screening for thyroid disease. Indications and side effects of therapeutic agents used in treatment are also presented.

Targeting the thyrotropin receptor in thyroid disease

INTRODUCTION

The thyrotropin receptor (TSHR) is essential for thyroid growth and for the production of thyroid hormones. It is unique among the glycoprotein hormone receptors, in that some of the TSHRs undergo cleavage and shedding of the alpha subunit.

AREAS COVERED

This review discusses the structure and function of the TSHR, followed by an evaluation of its role in thyroid disease. Possible limitations of the TSHR as a therapeutic target are also discussed.

EXPERT OPINION

The TSHR is involved in a number of hereditary and acquired disorders of the thyroid making it of potential importance as a therapeutic target in thyroid disease. Expression of the TSHR in several non-thyroidal tissues and the development of systemic manifestations of thyroid disease suggest that the TSHR is also of interest as a therapeutic target outside the thyroid.

Thyroid disorders during pregnancy

Thyroid disorders are common in women during pregnancy. If left untreated, both hypothyroidism and hyperthyroidism are associated with adverse effects on pregnancy and fetal outcomes. It is important to correctly identify these disorders and treat them appropriately to prevent pregnancy-related complications. Levothyroxine is the indicated treatment for hypothyroidism, and thionamides are the treatment of choice for hyperthyroidism; thyroidectomy may be indicated in select cases. When thyroid cancer is diagnosed during pregnancy, a decision must be made regarding performing thyroidectomy during the pregnancy or postponing surgical resection until the postpartum period. Radioactive iodine is absolutely contraindicated during pregnancy and lactation.

Do Thyroid Disrupting Chemicals Influence Foetal Development during Pregnancy?

Maternal euthyroidism during pregnancy is crucial for normal development and, in particular, neurodevelopment of the foetus. Up to 3.5 percent of pregnant women suffer from hypothyroidism. Industrial use of various chemicals—endocrine disrupting chemicals (EDCs)—has been shown to cause almost constant exposure of humans with possible harmful influence on health and hormone regulation. EDCs may affect thyroid hormone homeostasis by different mechanisms, and though the effect of each chemical seems scarce, the added effects may cause inappropriate consequences on, for example, foetal neurodevelopment. This paper focuses on thyroid hormone influence on foetal development in relation to the chemicals suspected of thyroid disrupting properties with possible interactions with maternal thyroid homeostasis. Knowledge of the effects is expected to impact the general debate on the use of these chemicals. However, more studies are needed to elucidate the issue, since human studies are scarce.

Antithyroid drug-induced fetal goitrous hypothyroidism

Maternal overtreatment with antithyroid drugs can induce fetal goitrous hypothyroidism. This condition can have a critical effect on pregnancy outcome, as well as on fetal growth and neurological development. The purpose of this Review is to clarify if and how fetal goitrous hypothyroidism can be prevented, and how to react when prevention has failed. Understanding the importance of pregnancy-related changes in maternal thyroid status when treating a pregnant woman is crucial to preventing fetal goitrous hypothyroidism. Maternal levels of free T(4) are the most consistent indication of maternal and fetal thyroid status. In patients with fetal goitrous hypothyroidism, intra-amniotic levothyroxine injections improve fetal outcome. The best way to avoid maternal overtreatment with antithyroid drugs is to monitor closely the maternal thyroid status, especially estimates of free T(4) levels.

Graves' disease in two pregnancies complicated by fetal goitrous hypothyroidism: successful in utero treatment with levothyroxine

BACKGROUND

Treatment of Graves' disease during pregnancy with antithyroid drugs (ATDs) poses a risk of inducing hypothyroidism and, thus, development of a goiter to the fetus.

PATIENT FINDINGS

We report two patients referred to our department after discovery of a fetal goiter by ultrasound examination in the second trimester of pregnancy. The women receiving 400 mg/day propylthiouracil and 10 mg/day thiamizole, respectively, had thyrotropin and total thyroxine values within the normal reference range but a lowered free thyroxine level. Fetal blood sampling by cordocentesis revealed severe fetal hypothyroidism as the cause of goiter development. Reduction of maternal ATD dose and injection of levothyroxine intra-amniotically quickly reduced the goiter size, and both babies were born euthyroid and without goiters.

SUMMARY

Two pregnant women with Graves' disease were overtreated with ATDs inducing iatrogenic goiter in the fetuses. Successful treatment with intra-amniotic levothyroxine injections rendered the babies euthyroid and nongoitrous at birth.

CONCLUSIONS

Correct interpretation of thyroid function tests during pregnancy in general--and during ATD therapy of Graves' disease in particular--is difficult. Awareness of pregnancy-related changes in maternal thyroid status, and a close teamwork among endocrinologists, obstetricians, and experts in fetal medicine, is pivotal in ensuring normal growth and development of the unborn child of these patients.

Thyroid function and human reproductive health

Via its interaction in several pathways, normal thyroid function is important to maintain normal reproduction. In both genders, changes in SHBG and sex steroids are a consistent feature associated with hyper- and hypothyroidism and were already reported many years ago. Male reproduction is adversely affected by both thyrotoxicosis and hypothyroidism. Erectile abnormalities have been reported. Thyrotoxicosis induces abnormalities in sperm motility, whereas hypothyroidism is associated with abnormalities in sperm morphology; the latter normalize when euthyroidism is reached. In females, thyrotoxicosis and hypothyroidism can cause menstrual disturbances. Thyrotoxicosis is associated mainly with hypomenorrhea and polymenorrhea, whereas hypothyroidism is associated mainly with oligomenorrhea. Thyroid dysfunction has also been linked to reduced fertility. Controlled ovarian hyperstimulation leads to important increases in estradiol, which in turn may have an adverse effect on thyroid hormones and TSH. When autoimmune thyroid disease is present, the impact of controlled ovarian hyperstimulation may become more severe, depending on preexisting thyroid abnormalities. Autoimmune thyroid disease is present in 5-20% of unselected pregnant women. Isolated hypothyroxinemia has been described in approximately 2% of pregnancies, without serum TSH elevation and in the absence of thyroid autoantibodies. Overt hypothyroidism has been associated with increased rates of spontaneous abortion, premature delivery and/or low birth weight, fetal distress in labor, and perhaps gestation-induced hypertension and placental abruption. The links between such obstetrical complications and subclinical hypothyroidism are less evident. Thyrotoxicosis during pregnancy is due to Graves' disease and gestational transient thyrotoxicosis. All antithyroid drugs cross the placenta and may potentially affect fetal thyroid function.

Screening for thyroid disease: defining high-risk populations

The pros and cons of population screening for thyroid disease have been hotly debated over the past several decades. This article addresses the issue from the point of view of the potential benefit of screening, that is, disease detection. Earlier diagnoses of hypothyroidism, hyperthyroidism, thyroid nodules, thyroid cancer and so on, with implementation of the indicated diagnostic and therapeutic interventions, avoid the adverse consequences of unrecognized and untreated progressive disease. Arguments against screening and case-finding often focus on cost considerations. To achieve the greatest yield at the lowest cost, our emphasis is on vulnerable populations with associated risk factors, and special situations such as pregnancy.

Thyroid hormone testing by tandem mass spectrometry

In the euthyroid person, absolute free thyroxine concentrations remain constant and correlate with the tissue hormone level, its biologic effect and the metabolic status of the patient. However, most circulating thyroid hormone is bound to plasma proteins and only a minute amount is in the unbound free form. Studies have shown that current free thyroxine immunoassays are binding protein dependent. Novel high-performance liquid chromatography tandem mass spectrometry (LC/MS/MS) methods have successfully dealt with problems inherent in many immunoassays for thyroid hormones and afforded improved specificity and accuracy in thyroid hormone measurements. We emphasize problems with thyroid hormone testing employing immunoassays including direct and indirect thyroid hormone immunoassays, sample processing, methods of free hormone separation and review the emerging role of liquid chromatography-tandem mass spectrometry in thyroid hormone testing. The latest generation of tandem mass spectrometers has superior limits of quantification, permitting omission of previously employed derivatization steps. Liquid chromatography-tandem mass spectrometry affords the specificity, precision, and limits of quantification necessary for the reliable measurement of thyroid hormones, enhancing diagnostic capabilities, and affording the profiles of the iodothyronines and thyronamines. These methods are especially important in states of disease and during pregnancy when protein binding is a factor that interferes with other methods for thyroid hormone analysis.

Thyroid function tests during first-trimester of pregnancy: a review of literature

This literature review was conducted to summarize the main points of maternal thyroid function tests, with particular attention in the first trimester of pregnancy which accompanied with significant biochemical and metabolic alteration. The evaluation of thyroid function of either hyperthyroidism and hypothyroidism should be assessed by determination of serum Thyroid Stimulating Hormone (TSH), Thyroxine (T4), Triiodothyronine (T3), Iodine and Thyroid Autoantibodies. Glomerular filtration rate is increased during pregnancy; therefor iodine deficiency should be evaluated during the pregnancy to prevent hypothyroidism. The role which can be played by Human Chronic Gonadotropin (hCG) on stimulating the thyroid gland to become over-active was investigated. Serum level ofthyroglobulin (Tg) and Thyroxin Binding Globulin (TBG) should be assessed for proper assessments of thyroid gland during pregnancy. Thyroid function tests during first-trimester of pregnancy and particularly the reference interval for thyroid function tests for pregnant women in each region has to be established, to prevent mis-diagnosis and irreversible mental and physical adverse affect for growing fetus.

Graves hyperthyroidism and pregnancy: a clinical update

OBJECTIVE

To provide a clinical update on Graves' hyperthyroidism and pregnancy with a focus on treatment with antithyroid drugs.

METHODS

We searched the English-language literature for studies published between 1929 and 2009 related to management of hyperthyroidism in pregnancy. In this review, we discuss differential diagnosis of hyperthyroidism, management, importance of early diagnosis, and importance of achieving proper control to avoid maternal and fetal complications.

RESULTS

Diagnosing hyperthyroidism during pregnancy can be challenging because many of the signs and symptoms are similar to normal physiologic changes that occur in pregnancy. Patients with Graves disease require prompt treatment with antithyroid drugs and should undergo frequent monitoring for signs of fetal and maternal hyperthyroidism and hypothyroidism. Rates of maternal and perinatal complications are directly related to control of hyperthyroidism in the mother. Thyroid receptor antibodies should be assessed in all women with hyperthyroidism to help predict and reduce the risk of fetal or neonatal hyperthyroidism or hypothyroidism. The maternal thyroxine level should be kept in the upper third of the reference range or just above normal, using the lowest possible antithyroid drug dosage. Hyperthyroidism may recur in the postpartum period as Graves disease or postpartum thyroiditis; thus, it is prudent to evaluate thyroid function 6 weeks after delivery. Preconception counseling, a multidisciplinary approach to care, and patient education regarding potential maternal and fetal complications that can occur with different types of treatment are important.

CONCLUSION

Preconception counseling and a multifaceted approach to care by the endocrinologist and the obstetric team are imperative for a successful pregnancy in women with Graves hyperthyroidism.

Autoimmune thyroid disease in pregnancy: a review

The maternal physiological changes that occur in normal pregnancy induce complex endocrine and immune responses. During a normal pregnancy, thyroid gland volume may enlarge, and thyroid hormone production increases. Hence, the interpretation of thyroid function during gestation needs to be adjusted according to pregnancy-specific ranges. The elevated prevalence of gestation-related thyroid disorders (10%-15%) and the important repercussions for both mother and fetus reported in multiple studies throughout the world denote, in our opinion, the necessity for routine thyroid function screening both before and during pregnancy. Once thyroid dysfunction is suspected or confirmed, management of the thyroid disorder necessitates regular monitoring in order to ensure a successful outcome. The aim of treating hyperthyroidism in pregnancy with antithyroid drugs is to maintain serum thyroxine (T(4)) in the upper normal range of the assay used with the lowest possible dose of drug, whereas in hypothyroidism, the goal is to return serum thyroid-stimulating hormone (TSH) to the range between 0.5 and 2.5 mU/L.