Antithyroid drug-induced fetal goitrous hypothyroidism

Fetal Hyperthyroidism with Maternal Hypothyroidism: Two Cases of Intrauterine Therapy

Fetal hyperthyroidism can occur secondary to maternal autoimmune hyperthyroidism. The thyroid-stimulating hormone receptor antibody (TRAb) transferred from the mother to the fetus stimulates the fetal thyroid and causes fetal thyrotoxicosis. Fetuses with this condition are difficult to detect, especially after maternal Graves disease therapy. Here, we present two cases of fetal hyperthyroidism with maternal hypothyroidism and review the assessment and intrauterine therapy for fetal hyperthyroidism. Both women were referred at 22+ and 23+ weeks of gestation with abnormal ultrasound findings, including fetal heart enlargement, pericardial effusion, and fetal tachycardia. Both women had a history of Graves disease while in a state of hypothyroidism with a high titer of TRAb. A sonographic examination showed a diffusely enlarged fetal thyroid with abundant blood flow. Invasive prenatal testing revealed no significant chromosomal aberration. Low fetal serum TSH and high TRAb levels were detected in the cord blood. Fetal hyperthyroidism was considered, and maternal oral methimazole (MMI) was administered as intrauterine therapy, with the slowing of fetal tachycardia, a reduction in fetal heart enlargement, and thyroid hyperemia. During therapy, maternal thyroid function was monitored, and the dosage of maternal levothyroxine was adjusted accordingly. Both women delivered spontaneously at 36+ weeks of gestation, and neonatal hyperthyroidism was confirmed in both newborns. After methimazole and propranolol drug treatment with levothyroxine for 8 and 12 months, both babies became euthyroid with normal growth and development.

Recommendations of the AGG (Working Group for Obstetrics, Department of Maternal Diseases) on How to Treat Thyroid Function Disorders in Pregnancy

Objective These recommendations from the AGG (Committee for Obstetrics, Department of Maternal Diseases) on how to treat thyroid function disorder during pregnancy aim to improve the diagnosis and management of thyroid anomalies during pregnancy.

Methods Based on the current literature, the task force members have developed the following recommendations and statements. These recommendations were adopted after a consensus by the members of the working group.

Recommendations The following manuscript gives an insight into physiological and pathophysiological thyroid changes during pregnancy, recommendations for clinical and subclinical hypo- and hyperthyroidism, as well as fetal and neonatal diagnostic and management strategies.

Analysis of Risk Factors and Screening Results of Neonatal Congenital Hypothyroidism in a Tertiary Care Center of Southern China

Objective

To explore the risk factors for neonatal congenital hypothyroidism (CH) and the influencing factors of false-positive results in CH screening.

Methods

In this study, 255 neonatal patients with CH who completed the screening and further diagnosis and 366 neonates with positive CH screening results and normal thyroid function were selected as the case group. 246 healthy neonates with normal thyroid function were selected as the control group. Gestational age, birth-weight, maternal age, small for gestational age (SGA), perinatal factors (gestational thyroid dysfunction, gestational diabetes mellitus, etc.) were used as influencing factors, using χ ² tests were performed for comparison. The statistically significant variables were analyzed with Logistic multiple regression models, and the difference was considered statistically significant (P<0.05).

Results

There were statistical differences in the SGA, maternal gestational diabetes mellitus, thyroid disease, and the proportion using assisted reproduction technology among the case group, false-positive screening group, and control group (χ ² was 11.943, 6.857, 6.999, 9.732, respectively, P < 0.05). The results of multivariate logistic regression analysis showed that the gestational thyroid disease (OR = 8.452, 95% CI:1.051-67.982), gestational diabetes mellitus (OR = 2.654, 95% CI:1.051-6.706), and assisted reproduction (OR = 0.194, 95% CI:0.041-0.911) were the influencing factors for neonatal CH, and the difference was statistically significant (P < 0.05). The SGA (OR = 2.556, 95% CI:1.027-6.361), gestational thyroid disease (OR = 7.801, 95% CI:1.03-59.057), gestational diabetes mellitus (OR = 2.731, 95% CI:1.18-6.322), and assisted reproduction (OR = 0.28, 95% CI:0.102-0.765) were the influencing factors of the false-positive screening results of neonatal CH. The difference was statistically significant (P < 0.05).

Conclusion

Neonatal CH and positive screening results are influenced by assisted reproduction, gestational thyroid dysfunction, gestational diabetes mellitus, and SGA.

Immediate postnatal central hypothyroidism caused by maternal Graves' disease: Importance of early screening

This report illustrates a case of central hypothyroidism in a newborn immediately after birth caused by maternal Graves' disease. Infants from mothers with Graves' disease require careful examination without waiting for neonatal screening results, even though the mother's thyroid function is normal at birth or the newborn does not have goiter.

Thyroid Disease in Pregnancy: A Descriptive Review of Guidelines

Importance

Thyroid disorders represent one of the most frequent complications of pregnancy associated with adverse obstetric, fetal, and neonatal outcomes, especially in case of delayed diagnosis and suboptimal management.

Objective

The aim of this study was to review and compare the recommendations of the most recently published guidelines on the diagnosis and management of these common conditions.

Evidence Acquisition

A descriptive review of guidelines from the Endocrine Society, the European Thyroid Association, the Royal Australian and New Zealand College of Obstetricians and Gynecologists, the American Thyroid Association, and the American College of Obstetricians and Gynecologists on thyroid disease in pregnancy was carried out.

Results

There is an overall consensus regarding the diagnosis of overt and subclinical hypothyroidism and hyperthyroidism in pregnancy using the pregnancy-specific reference ranges and the definition of postpartum thyroiditis. The reviewed guidelines unanimously discourage universal screening for thyroid function abnormalities before and during pregnancy and support targeted screening of high-risk patients by measuring serum thyroid-stimulating hormone levels. Moreover, they all highlight the need of treating overt hypothyroidism and hyperthyroidism, not only during pregnancy, but also before conception, suggesting similar management policies and treatment targets. There is also agreement regarding the management of gestational transient hyperthyroidism with hyperemesis gravidarum, suspected fetal thyrotoxicosis, postpartum thyroiditis, and thyroid malignancy. Scanning or treating with radioactive iodine is contraindicated during pregnancy and breastfeeding. On the other hand, there is controversy on the management of subclinical thyroid disease, thyroid function surveillance protocols, and iodine nutrition recommendations. Of note, the American College of Obstetricians and Gynecologists makes some specific recommendations on the treatment of thyroid storm and thyrotoxic heart failure in pregnant women, whereas the American Thyroid Association makes a special reference to the management of women with thyroid cancer.

Conclusions

As the disorders of the thyroid gland affect a significant proportion of pregnant women, it is of paramount importance to develop uniform international evidence-based protocols for their accurate diagnosis and optimal management, in order to safely guide clinical practice and eventually improve perinatal outcomes.

Hyperthyroidism in Pregnancy: The Delicate Balance between Too Much or Too Little Antithyroid Drug

Overt hyperthyroidism (HT) during pregnancy is associated with a risk of maternal–fetal complications. Antithyroid drugs (ATD) have a potential risk for teratogenic effects and fetal–neonatal hypothyroidism. This study evaluated ATD treatment and thyroid function control during pregnancy, and pregnancy outcome in women with HT. Patients and methods: A retrospective analysis of 36 single fetus pregnancies in 29 consecutive women (median age 30.3 ± 4.7 years) with HT diagnosed before or during pregnancy; a control group of 39 healthy euthyroid pregnant women was used. Results: Twenty-six women had Graves’ disease (GD, 33 pregnancies), 1 had a hyperfunctioning autonomous nodule, and 2 had gestational transient thyrotoxicosis (GTT). Methimazole (MMI) was administered in 22 pregnancies (78.5%), Propylthiouracil (PTU) in 2 (7.1%), switch from MMI to PTU in 4 (14.2%), no treatment in 8 pregnancies (3 with subclinical HT, 5 euthyroid with previous GD remission before conception). In the 8 pregnancies of GD patients diagnosed during gestation or shortly before (<6 weeks), i.e., with fetal exposure to uncontrolled HT, there was 1 spontaneous abortion at 5 weeks (3.4% of all ATD-treated pregnancies), and 1 premature delivery at 32 weeks with neonatal death in 24 h (3.4%); 1 child had neonatal hyperthyroidism (3.3% of live children in GD women) and a small atrial sept defect (4% of live children in ATD treated women). In women treated more than 6 months until conception (20 pregnancies): (a) median ATD doses were lower than those in women diagnosed shortly before or during pregnancy; (b) ATD was withdrawn in 40% of pregnancies in trimester (T)1, all on MMI < 10 mg/day (relapse in 14.2%), and in up to 55% in T3; (c) TSH level was below normal in 37%, 35% and 22% of pregnancies in T1, T2 and T3 respectively; FT4 was increased in 5.8% (T1) and subnormal in 11.75% in T2 and T3; (d) no fetal birth defects were recorded; one fetal death due to a true umbilical cord knot was registered. Mean birth weight was similar in both ATD-treated and control groups. Hyperthyroidism relapsed postpartum in 83% of GD patients (at median 3 ± 2.6 months). Conclusion: In hyperthyroid women with long-term ATD treatment before conception, drugs could be withdrawn in T1 in 40% of them, the thyroid function control was better, and pregnancy and fetal complications were rarer, compared to women diagnosed during pregnancy. Frequent serum TSH and FT4 monitoring is needed to maintain optimal thyroid function during pregnancy.

Dose-Dependent Influence of Antithyroid Drugs on the Difference in Free Thyroxine Levels between Mothers with Graves' Hyperthyroidism and Their Neonates

BACKGROUND

Several guidelines have recommended that the use of the lowest effective dose of antithyroid drugs (ATDs) that maintains maternal serum free thyroxine (FT4) levels at or moderately above the upper limit of the reference range is appropriate for fetal euthyroid status. However, little is known about whether ATD dosage affects the difference in serum FT4 levels between the mother and neonate. We conducted a retrospective study at a tertiary hospital in Japan to investigate the dose-dependent influence of ATDs on both maternal and fetal thyroid hormone status.

MATERIALS AND METHODS

We retrospectively examined 62 pregnant women who delivered between 2007 and 2016 and were treated for Graves' hyperthyroidism with ATD at any stage during pregnancy. We selected individuals whose data on maternal FT4 level within 4 weeks of their deliveries and cord FT4 level of their infants at the time of delivery were available. Those with multiple pregnancies, iodine or glucocorticoid treatment, and fetal goiter detected by ultrasonography were excluded.

RESULTS

After the exclusion criteria were applied, we recruited 40 individuals. The cord FT4 levels were significantly lower than the maternal FT4 levels in patients treated with high-dosage ATDs (methimazole >5 mg daily or propylthiouracil >100 mg daily). However, there were no significant differences between maternal and cord FT4 levels in patients treated with low-dosage ATDs (methimazole ≤5 mg daily or propylthiouracil ≤100 mg daily). We selected 35 individuals whose data on maternal thyrotropin receptor-binding inhibitory immunoglobulin (TBII) level were available. Multiple linear regression analysis adjusted for ATD dosage, maternal TBII level, and gestational period found that ATD dosage was a significant predictor of the difference in serum FT4 levels between the mother and neonate. In terms of maternal complications, multiple logistic regression analysis identified maternal free triiodothyronine (FT3) level as a significant predictor of the incidence of preterm delivery.

CONCLUSIONS

We found a dose-dependent influence of ATDs on the difference in serum FT4 levels between mothers with Graves' hyperthyroidism and their neonates. Further studies to evaluate the optimal target FT4 and FT3 levels for the mother and neonate during pregnancy may improve the outcome of pregnant women with Graves' hyperthyroidism.

Thyroid and Eye: Where They Meet in Clinical Practice

OBJECTIVE

Thyroid Hormones (TH) are essential for normal growth, development and continued optimal function of most of the body organs including the eye. TH signaling plays a central role in the regulation of retinal development and maturation. Deficiency in TH during fetal and early postnatal development impairs growth of the eye and proliferation of all retinal cell types. The present article reviews the most important topics of the different derangements in thyroid function and structure and its relation with eye diseases.

METHODS

A literature search strategy was conducted for all English-language literature.

RESULTS

From a clinical practice viewpoint, it should be mentioned that both hypothyroidism and hyperthyroidism are accompanied by ocular diseases i.e. thyroid-associated ophthalmopathy, diabetic retinopathy and age-related macular degeneration. Although the orbit and globe are not common sites for metastatic thyroid cancers, orbital metastasis may be the primary clinical manifestation of thyroid carcinoma. Finally, some medications as amiodarone may be accompanied by both thyroid dysfunction and adverse ocular events.

CONCLUSION

Thyroid disorders and eye diseases are interrelated through several mechanisms thus, awareness of this relation has a great impact on early diagnosis and treatment.

Management of thyrotoxicosis during pregnancy

Thyrotoxicosis during pregnancy should be adequately managed and controlled to prevent maternal and fetal complications. The evaluation of thyroid function in pregnant women is challenged by the physiological adaptations associated with pregnancy, and the treatment with antithyroid drugs (ATD) raises concerns for the pregnant woman and the fetus. Thyrotoxicosis in pregnant women is mainly of autoimmune origin, and the measurement of thyroid stimulating hormone-receptor antibodies (TRAb) plays a key role. TRAb helps to distinguish the hyperthyroidism of Graves' disease from gestational hyperthyroidism in early pregnancy, and to evaluate the risk of fetal and neonatal hyperthyroidism in late pregnancy. Furthermore, the measurement of TRAb in early pregnancy is recommended to evaluate the need for ATD during the teratogenic period of pregnancy. Observational studies have raised concern about the risk of birth defects associated with the use of ATD in early pregnancy and challenged the clinical management and choice of treatment.

Perinatal risk factors for congenital hypothyroidism: A retrospective cohort study performed at a tertiary hospital in China

Congenital hypothyroidism (CH) is one of the most common neonatal endocrine diseases. This retrospective cohort study aimed to identify the potential perinatal risk factors for CH and to differentiate between transient and permanent CH (TCH and PCH, respectively) as well as determine their prevalence in a southeastern Chinese population.This study was based on an 18-year surveillance of a neonatal CH screening program in a large tertiary hospital. A retrospective review of the maternal and neonatal perinatal exposures was conducted.Of the 205,834 newborns screened between 2000 and 2018, 189 were diagnosed with CH (1/1089). Among the 131 CH patients who again underwent thyroid function testing (TFT) after discontinuation of levothyroxine at the age of 3 years, 61 (46.6%) were diagnosed with PCH and 70 (53.4%) were diagnosed with TCH. In the maternal characteristics model, women aged 35 years or older and those who had thyroid disease and/or diabetes mellitus during pregnancy had increased risk of having an offspring with CH (P = .001, .000, and .001, respectively). Significant associations were found with regard to parity and the risk of CH in the offspring (P = .000). In the neonatal characteristics model, infants with female sex, preterm birth, post-term birth, low birth weight, other birth defects, and those born as part of multiple births (P = .011, .034, .001, .000, .000, and .003, respectively) had increased risk of CH. The rate of newborns with other birth defects was higher in the PCH group than that in the TCH group (P = .008), whereas the rate of maternal thyroid disease, newborns with low birth weight, and newborns with preterm birth was higher in the TCH group than that in the PCH group (P = .041, .020, and .013, respectively). The levothyroxine dose (μg/kg/day) at 1 year, 2 years, and 3 years old was significantly lower in the TCH group than that in the PCH group (P = .000, .000, and .000, respectively).Perinatal factors should be considered during the diagnosis and treatment of CH.

Maternal thyroid disease and its effects on the fetus and perinatal outcomes

Thyroid disease is common in women of childbearing age and can have significant effects on the development of the fetus and perinatal outcomes. Maternal thyroid hormone is critical for proper fetal neurodevelopment, and the fetus relies on thyroid hormone from its mother for the first half of pregnancy. Both overt maternal hypothyroidism and overt maternal hyperthyroidism have been shown to be associated with adverse effects on central nervous system gray matter and neurocognitive development of offspring as well as increased obstetrical risks. Treatment of overt thyroid conditions improves outcomes. Subclinical maternal hypothyroidism may increase adverse neurocognitive and obstetrical outcomes although data are conflicting. To date, treatment of subclinical hypothyroidism has not shown benefit. Subclinical hyperthyroidism is well tolerated in pregnancy. Thyroid autoantibodies alone may also affect neurodevelopment and obstetrical outcomes; however, recent data have shown no improvement with levothyroxine treatment. Several rare maternal genetic thyroid conditions can affect the fetus including a thyroid-stimulating hormone receptor mutation leading to hypersensitivity to human chorionic gonadotropin and thyroid hormone resistance. The thyroid plays a crucial role in fetal health and understanding it is important for optimal care.

Graves' hyperthyroidism in pregnancy

PURPOSE OF REVIEW

Graves' hyperthyroidism is associated with significant obstetric, maternal, fetal, and neonatal complications. Early diagnosis and an understanding of the management of Graves' hyperthyroidism in pregnancy can help to prevent these complications. Antithyroid drugs (ATD) should be avoided in early pregnancy, given their association with congenital malformations.

RECENT FINDINGS

TSH-receptor antibodies (TRAb) are integral in the management of Graves' hyperthyroidism in pregnancy and in the preconception period. TRAb are indicative of the current activity of Graves' hyperthyroidism and the likelihood of relapse. Furthermore, TRAb predicts the risk of fetal and neonatal hyperthyroidism.The incidence of congenital malformations is roughly the same for propylthiouracil (PTU) and methimazole (MMZ). Exposure to both ATDs in early pregnancy has been associated with increased incidence of congenital malformations compared with exposure to either ATD alone.

SUMMARY

The goal of the physician is maintaining euthyroidism throughout pregnancy and delivery of a healthy, euthyroid baby. An understanding of the natural progression of Graves' hyperthyroidism in pregnancy and the proper utilization of TRAb enables the physician to minimize the risks associated with Graves' hyperthyroidism and side effects of ATDs unique to pregnancy. The physician should prioritize preconception counseling in women with Graves' hyperthyroidism in order to avoid hyperthyroidism and having to use ATDs in pregnancy.

Graves' disease complicated by fetal goitrous hypothyroidism treated with intra-amniotic administration of levothyroxine

Fetal goitrous hypothyroidism is a rare entity and is caused mainly by maternal treatment of Graves' disease (GD). We report a case of a 22-year-old woman referred at 12 weeks of gestation due to hyperthyroidism subsequent to recently diagnosed GD. She started treatment with propylthiouracil and, at 21 weeks of gestation, fetal goitre was detected. A cordocentesis confirmed the diagnosis of fetal goitrous hypothyroidism, and intra-amniotic administration of levothyroxine (LT4) was performed and repeated through the pregnancy due to maintenance of fetal goitre. The pregnancy proceeded without further complications and a healthy female infant was born at 37 weeks of gestation, with visible goitre and thyroid function within the normal range at birth. Although there is no consensus on the optimal dose, the number of injections and the interval between them, intra-amniotic LT4 administration is recommended once fetal goitrous hypothyroidism is suspected, in order to prevent long-term complications of fetal hypothyroidism.

Current knowledge about the in utero and peripartum management of fetal goiter associated with maternal Graves' disease

Maternal Graves’ disease is the most common cause of fetal goiter. Fetal goiter can cause complications attributable either to the physical effects of the goiter itself or to thyroid dysfunction, which can be life-threatening and cause neurological impairment. Determining whether a goiter is caused by fetal hyperthyroidism or hypothyroidism is the main clinical problem, and in utero evaluations and management are essential. Ultrasonography combined with color Doppler and magnetic resonance imaging are helpful for the initial diagnosis and monitoring, but these imaging techniques have a limited ability to discriminate between fetal hyperthyroidism and hypothyroidism. To determine the fetal thyroid status, fetal blood sampling using cordocentesis is reliable but hazardous, and the indications must be considered carefully. Amniocentesis is an easier and safer alternative, but the correlations between the amniotic fluid and fetal serum thyroid hormone levels remain unclear. If a fetal goiter is accompanied by hypothyroidism, administering thyroid hormone intra-amniotically may be effective and relatively safe. However, the wide variety of approaches to treatment exemplifies the lack of guidelines, and no systematic studies have been conducted to date. Therefore, intrauterine treatment should be reserved for selected patients at a high risk of complications. Moreover, when intrauterine treatment fails and a fetal goiter can cause airway obstruction, intrapartum management, such as ex utero intrapartum treatment, may be required; however, reports describing the use of this procedure for fetal goiter are limited. This review summarizes the current knowledge about fetal goiter associated with maternal Graves’ disease and evaluates the most significant new findings regarding its in utero and peripartum management.

Hyperthyroidism in the pregnant woman: Maternal and fetal aspects

Hyperthyroidism during pregnancy is uncommon. Nonetheless, prompt identification and adequate management of hyperthyroidism in a pregnant woman is essential, because uncontrolled thyrotoxicosis significantly increases the risk of maternal and fetal complications. Also, fetal prognosis may be affected by the transplacental passage of maternal thyroid stimulating antibodies or thyrostatic agents, both of which may disrupt fetal thyroid function. Birth defects have been reported in association with the use of antithyroid drugs during early pregnancy. Although rarely, offspring of mothers with Graves’ disease may develop fetal/neonatal hyperthyroidism, the management of which requires a close collaboration between endocrinologists, obstetricians, and neonatologists.

Because of the above considerations, the management of pregnant and lactating women with hyperthyroidism requires special care, bearing in mind that both maternal thyroid excess per se and related treatments may adversely affect the newborn’s health.

In this review we discuss the diagnosis and management of hyperthyroidism in pregnancy, along with the impact of thyrotoxicosis and medications on fetal outcome.

A Practical Approach for the Verification and Determination of Site- and Trimester-Specific Reference Intervals for Thyroid Function Tests in Pregnancy

BACKGROUND

Population-, assay-, and trimester-specific reference intervals for thyroid function tests are necessary to assess thyroid status accurately and manage thyroid disease throughout pregnancy. This study's objective was to verify if the manufacturer's recommended trimester-specific reference intervals for thyroid tests and the American Thyroid Association's recommended total thyroxine (TT4) pregnancy reference intervals were verifiable and appropriate for use in the authors' multicultural population.

METHODS

Blood samples were obtained from the following sources: stored frozen surplus blood from women undergoing routine aneuploidy screening (first- and second-trimester samples, n = 274), women participating in an observational cohort study (second- and third-trimester samples, n = 135), and blood collected from women presenting for assessment to the labor and delivery ward (third-trimester samples, n = 35). Exclusions included thyroid medication or disease and positive thyroid peroxidase antibodies (anti-TPO). Samples were analyzed for thyrotropin (TSH), free T4 (fT4), free triiodothyronine (fT3), TT4, and anti-TPO using the Roche Cobas 8000 Modular e602 electrochemiluminescence immunoassay.

RESULTS

Nine percent of the aneuploidy screening samples were excluded prior to thyroid testing due to maternal use of thyroid medication. Six percent of analyzed samples were excluded: 5.9% with positive anti-TPO and one with a TSH >10 mIU/L. The manufacturer's recommended trimester-specific reference intervals for TSH were not verified by described standardized methods. Therefore, 95th percentile reference intervals were determined using a minimum number of samples. Reference intervals for TSH and fT4 were as follows: 9-12 weeks, 0.18-2.99 mIU/L and 11-19.2 pmol/L; second trimester, 0.11-3.98 mIU/L and 10.5-18.2 pmol/L; and third trimester, 0.48-4.71 mIU/L and 9.0-16.1 pmol/L, respectively. The TT4 reference interval after 19 weeks' gestation was 77-186 nmol/L.

CONCLUSIONS

This study provides a simple approach to verify or establish trimester-specific thyroid function reference intervals in local populations. The TT4 reference interval was lower than the interval proposed by the American Thyroid Association, suggesting the need for further study of TT4 in pregnancy and reliance on locally established fT4 reference intervals after 19 weeks, especially when there are no equivalent reference intervals for TT4.

MANAGEMENT OF THYROTOXICOSIS: PRECONCEPTION, PREGNANCY, AND THE POSTPARTUM PERIOD

OBJECTIVE

To review the diagnosis and management of thyrotoxicosis in women who are preconception, pregnant, and in the postpartum period.

METHODS

Literature review of English-language papers published between 1980 and 2018.

RESULTS

Overt thyrotoxicosis occurs in 0.2% of pregnancies and subclinical thyrotoxicosis in 2.5%. Hyperthyroidism in women of childbearing age most frequently is caused by Graves disease (GD). Gestational thyrotoxicosis, transient human chorionic gonadotropin (hCG)-mediated hyperthyroidism, may develop in the first trimester. In the first year following delivery, postpartum thyroiditis, which frequently includes a thyrotoxic phase, occurs in 5% of women. Hyperthyroidism from nodular autonomy is uncommon in women of childbearing age. It is essential to understand the underlying etiology for thyrotoxicosis in order to recommend appropriate treatment. Gestational thyrotoxicosis requires supportive care, without antithyroid drug therapy. GD may be treated with antithyroid drugs, radioactive iodine, or thyroidectomy. Pregnancy, plans for pregnancy, and lactation have important implications for the choice of GD treatment. When thyrotoxicosis presents following delivery, postpartum thyroiditis must be differentiated from GD.

CONCLUSION

The diagnosis and management of thyrotoxicosis in the peripregnancy period present specific challenges. In making management decisions, it is essential to weigh the risks and benefits of treatments not just for the mother but also for the fetus and for breastfed infants. A team approach to management is critical, with close collaboration among endocrinologists, maternal-fetal medicine specialists, and neonatologists.

ABBREVIATIONS

GD = Graves disease; hCG = human chorionic gonadotropin; MMI = methimazole; PPT = postpartum thyroiditis; PTU = propylthiouracil; T3 = triiodothyronine; T4 = thyroxine; TBG = thyroxine-binding globulin; TRAb = TSH receptor antibody; TSH = thyroid-stimulating hormone.

2018 European Thyroid Association Guideline for the Management of Graves' Hyperthyroidism

Graves' disease (GD) is a systemic autoimmune disorder characterized by the infiltration of thyroid antigen-specific T cells into thyroid-stimulating hormone receptor (TSH-R)-expressing tissues. Stimulatory autoantibodies (Ab) in GD activate the TSH-R leading to thyroid hyperplasia and unregulated thyroid hormone production and secretion. Diagnosis of GD is straightforward in a patient with biochemically confirmed thyrotoxicosis, positive TSH-R-Ab, a hypervascular and hypoechoic thyroid gland (ultrasound), and associated orbitopathy. In GD, measurement of TSH-R-Ab is recommended for an accurate diagnosis/differential diagnosis, prior to stopping antithyroid drug (ATD) treatment and during pregnancy. Graves' hyperthyroidism is treated by decreasing thyroid hormone synthesis with the use of ATD, or by reducing the amount of thyroid tissue with radioactive iodine (RAI) treatment or total thyroidectomy. Patients with newly diagnosed Graves' hyperthyroidism are usually medically treated for 12-18 months with methimazole (MMI) as the preferred drug. In children with GD, a 24- to 36-month course of MMI is recommended. Patients with persistently high TSH-R-Ab at 12-18 months can continue MMI treatment, repeating the TSH-R-Ab measurement after an additional 12 months, or opt for therapy with RAI or thyroidectomy. Women treated with MMI should be switched to propylthiouracil when planning pregnancy and during the first trimester of pregnancy. If a patient relapses after completing a course of ATD, definitive treatment is recommended; however, continued long-term low-dose MMI can be considered. Thyroidectomy should be performed by an experienced high-volume thyroid surgeon. RAI is contraindicated in Graves' patients with active/severe orbitopathy, and steroid prophylaxis is warranted in Graves' patients with mild/active orbitopathy receiving RAI.

Graves' hyperthyroidism in pregnancy: a clinical review

Background

Graves’ hyperthyroidism affects 0.2% of pregnant women. Establishing the correct diagnosis and effectively managing Graves’ hyperthyroidism in pregnancy remains a challenge for physicians.

Main

The goal of this paper is to review the diagnosis and management of Graves’ hyperthyroidism in pregnancy. The paper will discuss preconception counseling, etiologies of hyperthyroidism, thyroid function testing, pregnancy-related complications, maternal management, including thyroid storm, anti-thyroid drugs and the complications for mother and fetus, fetal and neonatal thyroid function, neonatal management, and maternal post-partum management.

Conclusion

Establishing the diagnosis of Graves’ hyperthyroidism early, maintaining euthyroidism, and achieving a serum total T4 in the upper limit of normal throughout pregnancy is key to reducing the risk of maternal, fetal, and newborn complications. The key to a successful pregnancy begins with preconception counseling.

FETAL GOITRE IN MATERNAL GRAVES' DISEASE

Fetal goitre is found in about 1 in 5,000 births, usually in association with maternal Graves' disease, due to transplacental passage of high levels of thyroid stimulating antibodies or of anti-thyroid drugs. A goitre can cause complications attributable to its size and to the associated thyroid dysfunction. Fetal ultrasound examination allows easy recognition of the goitre but is not reliable in distinguishing between fetal hypo- and hyperthyroidism. Assessment of the maternal condition and, in some cases, cordocentesis provide adequate diagnosis of the fetal thyroid function. First-line treatment consists of adjusting the dose of maternal anti-thyroid drugs. Delivery is aimed at term. In cases with large goitres, caesarean-section is indicated.

Maternal autoimmune disorders and fetal defects

Maternal autoantibodies can cross the placenta and cause fetal damage. This article summarizes the development and management of fetal thyroid goiter in response to maternal Graves' disease and/or its treatment with antithyroid medication, fetal heart block due to maternal anti-Ro and anti-La antibodies, fetal athrogryposis multiplex congenita in association with maternal myasthenia gravis and fetal brain hemorrhage due to maternal autoimmune thrombocytopenia.

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.

Managing hyperthyroidism in pregnancy: current perspectives

Hyperthyroidism in women who are of childbearing age is predominantly of autoimmune origin and caused by Graves' disease. The physiological changes in the maternal immune system during a pregnancy may influence the development of this and other autoimmune diseases. Furthermore, pregnancy-associated physiological changes influence the synthesis and metabolism of thyroid hormones and challenge the interpretation of thyroid function tests in pregnancy. Thyroid hormones are crucial regulators of early development and play an important role in the maintenance of a normal pregnancy and in the development of the fetus, particularly the fetal brain. Untreated or inadequately treated hyperthyroidism is associated with pregnancy complications and may even program the fetus to long-term development of disease. Thus, hyperthyroidism in pregnant women should be carefully managed and controlled, and proper management involves different medical specialties. The treatment of choice in pregnancy is antithyroid drugs (ATDs). These drugs are effective in the control of maternal hyperthyroidism, but they all cross the placenta, and so need careful management and control during the second half of pregnancy considering the risk of fetal hyper- or hypothyroidism. An important aspect in the early pregnancy is that the predominant side effect to the use of ATDs in weeks 6-10 of pregnancy is birth defects that may develop after exposure to available types of ATDs and may be severe. This review focuses on four current perspectives in the management of overt hyperthyroidism in pregnancy, including the etiology and incidence of the disease, how the diagnosis is made, the consequences of untreated or inadequately treated disease, and finally how to treat overt hyperthyroidism in pregnancy.

Sonographic Diagnosis of Fetal Goiter

The presence of a goiter in the fetus is an indication of maternal thyroid dysfunction. It carries an increased morbidity and mortality for the fetus and into the neonatal period. Maternal thyroid disease must be monitored closely and medications adjusted throughout pregnancy to prevent adverse outcomes. In females with poorly controlled thyroid disease, sonography is useful in the evaluation of the fetus at risk for goiter.

A rare case of dyshormonogenetic fetal goiter responding to intra-amniotic thyroxine injections

Fetal goiter was detected by routine ultrasound in early pregnancy, gestational week (GW) 18, in a 28-year-old woman with no thyroid history, normal thyroid hormone levels and no TSH receptor or thyroid peroxidase antibodies. An umbilical cord blood sample was drawn in GW 23. The analysis indicated fetal hypothyroidism with TSH >100 mU/l (reference value 6.8 ± 2.9, mean ± SD), fT4 3.8 pmol/l (reference value 16.5 ± 5.3, mean ± SD). Intra-amniotic injections of thyroxine were given in conjunction with ultrasound every 7-10 days, in total nine times during GW 24-33. A dose of 10 µg thyroxine/kg of estimated fetal weight per day was administered on six occasions, and 5 µg/kg/day the last three times. Upon injections of thyroxine further growth of the goiter was reduced. Elevated amniotic TSH levels fell from 13 to 2.5 mU/l (reference range 0.04-0.51). Throughout pregnancy, fetal heart rate and skeletal maturation were within normal limits. In week 34, chorioamnionitis was suspected and the child was delivered by cesarean section. Cord blood revealed TSH 596 mU/l (reference value 8.0 ± 5.12, mean ± SD), fT4 4.4 pmol/l (reference value 19.3 ± 4.3, mean ± SD) and total T3 1.18 nmol/l (reference value 0.5 ± 0.3, mean ± SD); the newborn was put on thyroxine supplementation. Psychomotor development of the child, now 3 years old, has been uneventful. The reported experience of treating dyshormonogenetic fetal goiter is limited but growing, creating a need for guidelines on administration of intra-amniotic thyroxine and monitoring treatment.

Gestational age-specific reference ranges from different laboratories misclassify pregnant women's thyroid status: comparison of two longitudinal prospective cohort studies

OBJECTIVES

Correct interpretation of thyroid status during pregnancy is vital to secure fetal development. Pregnancy-related changes in maternal thyroid status necessitate the use of gestational age-specific reference ranges. In this study, we investigated between-laboratory reproducibility of thyroid reference ranges in pregnant women.

DESIGN

Comparison of two longitudinal prospective cohort studies including 255 (cohort 1) and 101 (cohort 2) healthy antibody-negative Danish pregnant women attending prenatal care at Copenhagen University Hospital.

METHODS

Different immunoassays were used to measure thyroid hormone levels in the two cohorts. Thyroid hormone reference ranges were established for every 5 weeks of gestation. Differences between cohorts were explored through mixed-model repeated measures regression analyses. By applying reference ranges from one cohort to the other, the proportion of women who would be misclassified by doing so was investigated.

RESULTS

TSH increased and free thyroxine (FT4) decreased as pregnancy progressed. Results indicated highly significant differences between cohorts in free triiodothyronine (F=21.3, P<0.001) and FT4 (F=941, P<0.001). TSH levels were comparable (P=0.09). Up to 90.3% of the women had FT4 levels outside their laboratory's nonpregnant reference range, and up to 100% outside the other cohort's gestational-age-specific reference ranges. Z-score-based reference ranges markedly improved comparison between cohorts.

CONCLUSION

Even in the same region, the use of gestational-age-specific reference ranges from different laboratories led to misclassification. Up to 100% of maternal FT4 levels fell outside the other cohort's reference range despite similar TSH levels. In clinical practice, thyroid testing of pregnant women without adding method specificity to gestational age-dependent reference ranges will compromise patient safety.

Hyperthyroidism in pregnancy

Changes in thyroid hormone concentrations that are characteristic of hyperthyroidism must be distinguished from physiological changes in thyroid hormone economy that occur in pregnancy, especially in the first trimester. Approximately one to two cases of gestational hyperthyroidism occur per 1000 pregnancies. Identification of hyperthyroidism in a pregnant woman is important because adverse outcomes can occur in both the mother and the offspring. Graves' disease, which is autoimmune in nature, is the usual cause; but hyperthyroidism in pregnancy can be caused by any type of hyperthyroidism--eg, toxic multinodular goitre or solitary autonomously functioning nodule. Gestational transient thyrotoxicosis is typically reported in women with hyperemesis gravidarum, and is mediated by high circulating concentrations of human chorionic gonadotropin. Post-partum thyroiditis occurs in 5-10% of women, and many of those affected ultimately develop permanent hypothyroidism. Antithyroid drug treatment of hyperthyroidism in pregnant women is controversial because the usual drugs--methimazole or carbimazole--are occasionally teratogenic; and the alternative--propylthiouracil--can be hepatotoxic. Fetal hyperthyroidism can be life-threatening, and needs to be recognised as soon as possible so that treatment of the fetus with antithyroid drugs via the mother can be initiated. In this Review, we discuss physiological and pathophysiological changes in thyroid hormone economy in pregnancy, the diagnosis and management of hyperthyroidism during pregnancy, severe life-threatening thyrotoxicosis in pregnancy, neonatal thyrotoxicosis, and post-partum hyperthyroidism.

Side effects of anti-thyroid drugs and their impact on the choice of treatment for thyrotoxicosis in pregnancy

INTRODUCTION

Hyperthyroidism in pregnancy is a serious condition and its management is complex. Whilst carbimazole/methimazole (CBZ/MMI) and propylthiouracil (PTU) have similar efficacies in controlling hyperthyroidism, their risk of side effects such as major congenital abnormalities and hepatotoxicity are different.

METHODS

Various combinations of the terms 'anti-thyroid drugs', 'thionamide', 'carbimazole', 'methimazole', 'propylthiouracil', 'pregnancy', 'side effects', 'agranulocytosis', 'birth defects', 'congenital malformations', 'embryopathy', 'aplasia cutis', 'hepatotoxicity', 'hepatic failure', 'maternal' and 'fetus' were used to search MEDLINE and the Cochrane library. The references of retrieved papers were also reviewed.

RESULTS

There is increasing evidence for a CBZ/MMI embryopathy, whilst data remain lacking for major congenital abnormalities with PTU. In contrast, PTU is associated with increased risk of severe liver injury. Management strategies to reduce these risks by using PTU in the first trimester and CBZ/MMI in the later trimesters remain untested.

CONCLUSION

More evidence is still needed in defining the relative risks between CBZ/MMI and PTU of major congenital abnormalities and severe liver injury in pregnancy. Studies are also needed to establish the suitability of recent management suggestions in switching from PTU to CBZ/MMI after the first trimester. Major adverse outcomes secondary to CBZ/MMI and PTU are rare, and inadequately treated hyperthyroidism poses a far greater risk.

Propylthiouracil is teratogenic in murine embryos

Background

Hyperthyroidism during pregnancy is treated with the antithyroid drugs (ATD) propylthiouracil (PTU) and methimazole (MMI). PTU currently is recommended as the drug of choice during early pregnancy. Yet, despite widespread ATD use in pregnancy, formal studies of ATD teratogenic effects have not been performed.

Methods

We examined the teratogenic effects of PTU and MMI during embryogenesis in mice. To span different periods of embryogenesis, dams were treated with compounds or vehicle daily from embryonic day (E) 7.5 to 9.5 or from E3.5 to E7.5. Embryos were examined for gross malformations at E10.5 or E18.5 followed by histological and micro-CT analysis. Influences of PTU on gene expression levels were examined by RNA microarray analysis.

Results

When dams were treated from E7.5 to E9.5 with PTU, neural tube and cardiac abnormalities were observed at E10.5. Cranial neural tube defects were significantly more common among the PTU-exposed embryos than those exposed to MMI or vehicle. Blood in the pericardial sac, which is a feature indicative of abnormal cardiac function and/or abnormal vasculature, was observed more frequently in PTU-treated than MMI-treated or vehicle-treated embryos. Following PTU treatment, a total of 134 differentially expressed genes were identified. Disrupted genetic pathways were those associated with cytoskeleton remodeling and keratin filaments. At E 18.5, no gross malformations were evident in either ATD group, but the number of viable PTU embryos per dam at E18.5 was significantly lower from those at E10.5, indicating loss of malformed embryos. These data show that PTU exposure during embryogenesis is associated with delayed neural tube closure and cardiac abnormalities. In contrast, we did not observe structural or cardiac defects associated with MMI exposure except at the higher dose. We find that PTU exposure during embryogenesis is associated with fetal loss. These observations suggest that PTU has teratogenic potential.

Challenges in interpretation of thyroid function tests in pregnant women with autoimmune thyroid disease

Physiological changes during gestation are important to be aware of in measurement and interpretation of thyroid function tests in women with autoimmune thyroid diseases. Thyroid autoimmune activity is decreasing in pregnancy. Measurement of serum TSH is the first-line screening variable for thyroid dysfunction also in pregnancy. However, using serum TSH for control of treatment of maternal thyroid autoimmunity infers a risk for compromised foetal development. Peripheral thyroid hormone values are highly different among laboratories, and there is a need for laboratory-specific gestational age-related reference ranges. Equally important, the intraindividual variability of the thyroid hormone measurements is much narrower than the interindividual variation (reflecting the reference interval). The best laboratory assessment of thyroid function is a free thyroid hormone estimate combined with TSH. Measurement of antithyroperoxidase and/or TSH receptor antibodies adds to the differential diagnosis of autoimmune and nonautoimmune thyroid diseases.