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

NADPH Oxidase 3: Beyond the Inner Ear

Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.

Clinical Characteristics and Outcomes of Patients With Antithyroid Drug-Related Liver Injury

Context

Antithyroid drugs (ATDs) are the cornerstone of hyperthyroidism management. Hepatotoxicity due to ATDs can range from mild transaminase elevation to liver transplantation requirement and mortality.

Objective

The primary objective of the systematic review was to assess the clinical characteristics and outcomes of patients with drug induced liver injury (DILI) due to ATDs.

Methods

We conducted a systematic review of PUBMED, SCOPUS, and EMBASE on characteristics and outcomes of adults (>18 years) with DILI due to ATDs. We defined DILI as bilirubin ≥2.5 mg/dL or international normalized ratio >1.5 with any rise in alanine aminotransferase (ALT), aminotransferase (AST), or alkaline phosphatase (ALP), or an elevation of ALT or AST >5 times or ALP >2 times the upper limit of normal without jaundice/coagulopathy.

Results

The review included 100 articles describing 271 patients; 148 (70.8%) were female (N = 209). Mean age was 42.9 ± 17.2 years. Graves' disease was the most common indication for ATDs. Carbimazole/methimazole (CBM/MMI) was the most common offending agent (55.7%). DILI pattern was hepatocellular in 41.8%, cholestatic in 41.3%, and mixed in 16.9%. Outcomes included death in 11.8%, liver transplantation in 6.4%, partial improvement in 2.2%, and complete resolution in 79.6% with a median time (IQR) to resolution of 45 (20-90) days. Patients in the propylthiouracil (PTU) group had higher initial bilirubin, initial AST, initial ALT, peak ALT, peak AST, severe and fatal DILI, liver transplantation, and mortality than CBM/MMI. Rechallenge of antithyroid medication was infrequently reported (n = 16) but was successful in 75%.

Conclusion

DILI due to ATDs can present with different patterns and should prompt immediate drug discontinuation. Referral to a hepatologist should be considered if severe as transplantation is sometimes required. PTU-induced DILI may have worse outcomes than CBM/MMI.

A Case of Aplasia Cutis Congenita in the Setting of Maternal Carbimazole Use in the First Trimester

Aplasia cutis congenita (ACC) is one of several congenital malformations associated with antithyroid/thiourylene drug use in pregnancy. While uncommon among the general population (1-3/100 000 cases), the risk among those on thiourylenes is between 1.6% and 3%. The scalp is the most common site for this congenital anomaly. We present the case of a male infant with multifocal ACC of the scalp discovered at birth and born to a mother with Graves disease that was controlled during pregnancy using carbimazole. Thyroid function tests were normal throughout the pregnancy. There was no involvement of underlying subcutaneous tissue or structures. At age 18 months, the single largest lesion remained with only partial coverage. Prospective management involved periodic surveillance with planned 2-stage repair. This case reinforces the association between the antithyroid drugs carbimazole (CMZ) and methimazole (MMI) and supports the proposition of an MMI/CMZ embryopathy. It adds to a literature of case reports in which malformations arise in offspring of such mothers whose thyrotoxicosis is controlled antenatally, thereby challenging the suggestion that ACC is attributable to poorly controlled disease rather than thiourylenes. As yet the underlying mechanism is not understood, nor is it known why MMI and CMZ may cause potentially significant embryopathy while congenital defects attributable to the structurally similar propylthiouracil are typically less severe.

Preconception Management of Hyperthyroidism and Thyroid Status in Subsequent Pregnancy: A Population-Based Cohort Study

CONTEXT

Optimal thyroid status in pregnancy is essential in reducing the risk of adverse outcomes. The management of hyperthyroidism in women of reproductive age poses unique challenges and it is unclear how preconception treatment strategies impact on thyroid status in subsequent pregnancy.

OBJECTIVE

We aimed to determine trends in the management of hyperthyroidism before and during pregnancy and to assess the impact of different preconception treatment strategies on maternal thyroid status.

METHODS

We utilized the Clinical Practice Research Datalink database to evaluate all females aged 15-45 years with a clinical diagnosis of hyperthyroidism and a subsequent pregnancy (January 2000 to December 2017). We compared thyroid status in pregnancy according to preconception treatment, namely, (1) antithyroid drugs up to or beyond pregnancy onset, (2) definitive treatment with thyroidectomy or radioiodine before pregnancy, and (3) no treatment at pregnancy onset.

RESULTS

Our study cohort comprised 4712 pregnancies. Thyrotropin (TSH) was measured in only 53.1% of pregnancies, of which 28.1% showed suboptimal thyroid status (TSH >4.0 mU/L or TSH <0.1 mU/L plus FT4 >reference range). Pregnancies with prior definitive treatment were more likely to have suboptimal thyroid status compared with pregnancies starting during antithyroid drug treatment (odds ratio 4.72, 95% CI 3.50-6.36). A steady decline in the use of definitive treatment before pregnancy was observed from 2000 to 2017. One-third (32.6%) of first trimester carbimazole-exposed pregnancies were switched to propylthiouracil while 6.0% of propylthiouracil-exposed pregnancies switched to carbimazole.

CONCLUSION

The management of women with hyperthyroidism who become pregnant is suboptimal, particularly in those with preconception definitive treatment, and needs urgent improvement. Better thyroid monitoring and prenatal counseling are needed to optimize thyroid status, reduce teratogenic drug exposure, and ultimately reduce the risk of adverse pregnancy outcomes.

Long-term outcome of treatments for Graves disease in the children and adolescent population

BACKGROUND

Several studies were conducted over the years to find a significant association between non-surgical therapies such as Antithyroid Drug (ATD) Therapy and Radio-iodo therapy (RIT) with Graves' disease (GD) remission and relapse. However, these investigations did not have a specific focus on the age category of children and adolescents. Hence, this Research is performed to assess the association of non-surgical therapy (ATD and RIT) with Graves' disease (GD) remission and relapse in the children and adolescent population.

DESIGN

A systematic review and meta-analysis of observational studies and clinical trials were carried out.

METHODS

A systematic search of PubMed, EMBASE, and SCOPUS from their inception till April 2022 was performed for studies stating an association between ATD therapy and GD remission and relapse in participants 1-17 years old. The random-effects model was used in the meta-analysis to provide a pooled proportion of both primary outcomes. The quality and each study were assessed using the Newcastle Ottawa Scale (NOS).

RESULT

From 6195 studies searched from the databases, only 16 relevant articles remained after a detailed evaluation. These studies, having a total of 2557 patients aged 5-17 years, were involved in the analysis with a pooled estimate showing a significant association of ATD therapy with GD remission (Estimate: 0.400, 95% Confidence interval: 0.265-0.535; I^2 = 98.16%) and with GD relapse (Estimate: 0.359, 95% Confidence interval: 0.257-0.461; I^2 = 98.26%). Subgroup analyses were conducted to assess the remission rate of different therapies suggesting that antithyroid drugs play a significant role in the remission of the patients. All included studies were classified as moderate quality.

CONCLUSION

Following meta-analysis suggested that the ATD used in the analysis is effective in remitting GD in the children and adolescents population. Nevertheless, long-term RIT therapy and thyroidectomy leads to hypothyroidism. Still, large-sample, and high-quality studies targeting ATDs' use in children and adolescents with long-term surveillance of prognosis are needed.

Effect of a polyherbal formulation on L-thyroxine induced hyperthyroidism in a rat model: In vitro and in vivo analysis and identification of bioactive phytochemicals

An excess of thyroid hormones in the blood characterizes hyperthyroidism. Long-term use of prescription medications to treat hyperthyroidism has substantial adverse effects, and when discontinued, the symptoms frequently recur. Several plant species have been utilized to cure hyperthyroidism. In the present work, we investigated the impact of polyherbal extract (POH) of four medicinal plants to treat hyperthyroidism. Biochemical analysis revealed the presence of a high concentration of phytochemicals in the POHs. The in vitro antioxidant study revealed their antioxidant and free radical scavenging capacity. The gas chromatography coupled mass spectrometry analysis of the POHs showed the presence of 13 bioactive phytochemical compounds. The effect of various concentrations of POHs on L-thyroxine-induced hyperthyroidism in Wistar albino rats was evaluated for 18 days. The TSH, T3, and T4 levels increased significantly and reduced the increase of liver enzymes caused by hyperthyroidism in POH-treated rats. The data showed that POH therapy could restore thyroid function to normal. The injection of POH increased the size comprising vacuolated cells, columnar follicular cells, and highly coloured nuclei with increasing POH content, and the number of normal thyroid follicles rose. The findings indicate that polyherbal formulations of these medicinal plants include credible antithyroid compounds that may offer a protective and effective alternative treatment to synthetic thyroid medications.

Management of Hyperthyroidism during Pregnancy: A Systematic Literature Review

In pregnancy, several physiological changes affect maternal circulating thyroid hormone levels. The most common causes of hyperthyroidism in pregnancy are Graves' disease and hCG-mediated hyperthyroidism. Therefore, evaluating and managing thyroid dysfunction in women during pregnancy should ensure favorable maternal and fetal outcomes. Currently, there is no consensus regarding an optimal method to treat hyperthyroidism in pregnancy. The term "hyperthyroidism in pregnancy" was searched in the PubMed and Google Scholar databases to identify relevant articles published between 1 January 2010 and 31 December 2021. All of the resulting abstracts that met the inclusion period were evaluated. Antithyroid drugs are the main therapeutic form administered in pregnant women. Treatment initiation aims to achieve a subclinical hyperthyroidism state, and a multidisciplinary approach can facilitate this process. Other treatment options, such as radioactive iodine therapy, are contraindicated during pregnancy, and thyroidectomy should be limited to severe non-responsive thyroid dysfunction pregnant patients. In light of this events, even in the absence of guidelines certifying screening, it is recommended that all pregnant and childbearing women should be screened for thyroid conditions.

Hormonal and inflammatory modulatory effects of hesperidin in hyperthyroidism-modeled rats

The goal of the current study was to investigate the hormonal modulatory efficiency of hesperidin, through its regulatory potential of immunological, inflammatory, and/or antioxidant changes in on hyperthyroidism modeled adult female albino rats. Both normal and hyperthyroidism modeled rats (140-160g) were randomly divided into four groups (10 animals each) as follows: 1) healthy animals were daily ingested with saline for six weeks, and served as control group, 2) healthy animals were intraperitoneally injected with hesperidin (50 mg/kg/day) for a similar period, 3) hyperthyroidism-modeled animals without any treatment acted as positive control, and 4) hyperthyroidism-modeled animals were treated intraperitoneally with hesperidin for a similar period. The findings showed that hesperidin significantly modulated hyperthyroidism deteriorations, this was evidenced by a remarkable decline in serum T4, FT4, T3, FT3, TNF-α, IL1β-, IL4-, IL-6, and IL-10 levels, with a minor increase in TSH and significant raise in CD4+ level. Similarly, valuable improvement was observed in the oxidative status; serum SOD, GPx, CAT, and GSH levels were dramatically enhanced, associated with remarkable drop in MDA and NO levels. Also, hesperidin demonstrated nephro-hepatoprotective and anti-atherogenic potential, this was achieved from the notable reduction in ALAT and ASAT activities as well as urea, creatinine, cholesterol, and triglyceride close to the corresponding values of healthy group. These findings were supported by histological and immunohistochemical ones that showed a notable decrease in the expression of the calcitonin antibody. In conclusion, hesperidin possesses anti-hyperthyroidism, immunoinflammatory regulatory, and antioxidant activities that evidenced from the improvement of physio-architecture of the thyroid gland, reduction of inflammation and restoration of the impaired oxidative stress. This effect might be mechanized through immunological, inflammatory, apoptotic, and/or antioxidant modulatory pathways.

Evaluating thyroid function in pregnant women

Thyroid hormones are primarily responsible for regulating the basal metabolic rate but also make important contributions to reproductive function and fetal development. Both hyper- and hypothyroidism in pregnancy have been associated with increased risks of complications that include preeclampsia and low birth weight, among others. Furthermore, thyroid hormone deficiency in the developing fetus results in neurodevelopmental delay. As the fetus is exclusively reliant on maternal thyroid hormone for most of the first trimester and requires continued maternal supply until birth, identifying maternal thyroid dysfunction is critically important. However, evaluating thyroid function in pregnancy is challenging because of the many physiological changes that affect concentrations of thyroid-related analytes. Increasing plasma human chorionic gonadotropin (hCG) concentrations in the second half of the first trimester elicit a corresponding transient decrease in thyroid-stimulating hormone (TSH), and continually increasing estradiol concentrations throughout pregnancy cause substantial increases in thyroxine-binding globulin (TBG) and total thyroxine (T4) relative to the nonpregnant state. Lastly, free T4 concentrations gradually decrease with increasing gestational age. For these reasons, it is essential to interpret thyroid function test results in the context of trimester-specific reference intervals to avoid misclassification of thyroid status. This review summarizes the effects of thyroid dysfunction prior to conception and during pregnancy and describes considerations for the laboratory assessment of thyroid function in pregnant women.

Association between perinatal factors and hypospadias in newborns: a retrospective case-control study of 42,244 male infants

Background

Hypospadias is one of the most common male congenital malformations worldwide. It is characterised by the abnormal positioning of the opening of urethra, and may lead to problems with urination and sexual function. Various factors were suggested to contribute to hypospadias pathogen. This study aimed to evaluate the relationship between perinatal factors and neonatal hypospadias based on a large sample of male newborns.

Methods

This retrospective case–control study was conducted at the International Peace Maternal and Child Health Hospital, Shanghai Jiao Tong University School of Medicine. Male infants with hypospadias (N = 97) and without any birth defects (N = 42,147) who were born in January 2015 to December 2019 were enrolled in this study. A statistical analysis of perinatal factors, such as maternal age, primiparity, multiple births, hypertensive disorders of pregnancy (HDP), diabetes mellitus (DM), placenta previa, thyroid diseases, hepatitis B, obesity, meconium-stained amniotic fluid, gestational age, low birth weight (LBW), small for gestational age (SGA) and in vitro fertilization (IVF) was used to assess the risk factors for hypospadias.

Results

The overall incidence of hypospadias in male infants was 0.23% (97/42,244). The univariate analysis of potential risk factors for hypospadias showed that HDP, primiparity, multiple births, hyperthyroidism, preterm delivery, LBW and SGA had a statistical association with hypospadias. After adjusting for potential confounders in a multivariate regression analysis, the odds ratios (OR) and 95% confidence intervals (CI) were calculated for the following risk factors for hypospadias: HDP (OR: 3.965, 95% CI: 2.473–6.359, P <  0.01), multiple births (OR: 2.607, 95% CI: 1.505–4. 514, P <  0.01) and hyperthyroidism (OR:4.792, 95% CI: 1.700–13.506, P <  0.01), which suggested these factors were significant independent risk factors for hypospadias.

Conclusions

Perinatal factors, such as HDP, multiple births and hyperthyroidism may be associated with hypospadias in male infants.

Antithyroid drug therapy in pregnancy and risk of congenital anomalies: Systematic review and meta-analysis

OBJECTIVES

The risk of congenital anomalies following in utero exposure to thionamide antithyroid drugs (ATDs) is unresolved. Observational studies are contradictory and existing meta-analyses predate and preclude more recent studies. We undertook an updated meta-analysis of congenital anomaly risk in women exposed to carbimazole or methimazole (CMZ/MMI), propylthiouracil (PTU), or untreated hyperthyroidism in pregnancy.

METHODS

We searched Medline, Embase, and the Cochrane database for articles published up till August 2021. We pooled separate crude and adjusted risk estimates using random effects models and subgroup analyses to address heterogeneity.

RESULTS

We identified 16 cohort studies comprising 5957, 15,785, and 15,666 exposures to CMZ/MMI, PTU, and untreated hyperthyroidism, respectively. Compared to nondisease controls, adjusted risk ratio (RR) and 95% confidence intervals (95% CIs) for congenital anomalies was increased for CMZ/MMI (RR, 1.28; 95% CI, 1.06-1.54) and PTU (RR, 1.16; 95% CI, 1.08-1.25). Crude risk for CMZ/MMI was increased relative to PTU (RR, 1.20; 95% CI, 1.01-1.43). Increased risk was also seen with exposure to both CMZ/MMI and PTU, that is, women who switched ATDs in pregnancy (RR, 1.51; 95% CI, 1.14-1.99). However, the timing of ATD switch was highly variable and included prepregnancy switches in some studies. The excess number of anomalies per 1000 live births was 17.2 for patients exposed to CMZ/MMI, 9.8, for PTU exposure, and 31.4 for exposure to both CMZ/MMI and PTU. Risk in the untreated group did not differ from control or ATD groups. The untreated group was however highly heterogeneous in terms of thyroid status. Subgroup analysis showed more positive associations in studies with >500 exposures and up to 1-year follow-up.

CONCLUSIONS

ATD therapy carries a small risk of congenital anomalies which is higher for CMZ/MMI than for PTU and does not appear to be reduced by switching ATDs in pregnancy. Due to key limitations in the available data, further studies will be required to clarify the risks associated with untreated hyperthyroidism and with switching ATDs in pregnancy.

Preconception Counseling and Care for Pregnant Women with Thyroid Disease

Thyroid disease is associated with adverse maternal and fetal outcomes. Appropriate reference ranges should be used for the interpretation of test results, although universal screening for thyroid dysfunction is not warranted. Overt thyroid dysfunction requires careful consideration of medication adjustments and close monitoring. Mild thyroid hypofunction has been linked to adverse pregnancy outcomes including preterm delivery, and poor neurocognition in the offspring. This review summarizes the most recent evidence on the counseling and management of women with thyroid disease before and during pregnancy and highlights the areas of controversy in need of further research.

Neonatal Outcomes of Pregnancies Complicated by Maternal Hyperthyroidism

Objective

This study aimed to determine the proportion, clinical characteristics, hormonal status, median time for normalization of serum thyroxine (FT4) and thyroid-stimulating hormone (TSH) and factors affecting time to thyroid function test (TFT) normalization of neonates born to mothers with maternal hyperthyroidism admitted in our institution.

Methodology

This was a retrospective cohort study that included 170 newborns admitted to the Neonatal Intensive Care Unit (NICU) of Hospital Universiti Sains Malaysia (HUSM) with a history of maternal hyperthyroidism from January 2013 until December 2018. We analyzed their baseline demographic and clinical characteristics, maternal thyroid status and antibody levels. Finally, we analyzed newborn thyroid function and thyroid antibodies.

Results

The proportion of neonates born to mothers with maternal hyperthyroidism was 0.8% (170 of 20,198 neonates within the study period). Seven (4.1%) developed overt hyperthyroidism, while four (2.4%) had thyroid storm. The median time for thyroid function test normalization was 30 days (95% CI: 27.1 to 32.8). The median time for TFT normalization was longer among neonates of mothers with positive thyroid antibodies [46.6 days (95% CI, 20.6 to 39.4)] and of mothers who received anti-thyroid treatment [31.7 days (95% CI, 23.5 to 39.9)].

Conclusion

Neonates born to mothers with hyperthyroidism is uncommon. These babies were observed to have a longer time for normalization of thyroid function tests if their mothers had thyroid antibodies or received anti-thyroid treatment.

Hyperthyroidism management during pregnancy and lactation (Review)

Thyroid dysfunction is a significant public health issue, affecting 5-10 more women compared to men. The estimated incidence is up to 12% and only for women the treatment rises up to 4.3 billion dollars annually. Thyroid pathology can have a major impact on female fertility and it can only be detected when preconception tests are performed. Untreated or poorly treated hyperthyroidism in a mother can affect the fetal development and pregnancy outcome. Between 0.1 and 0.4% of the pregnancies are affected by clinical hyperthyroidism. Thyroid dysfunction is associated with higher rates of pregnancy loss. Hyperthyroidism can complicate fetal health problems intrauterinely and in the neonatal period. The TSH receptor is stimulated by TSH and HCG which has a similar structure. This can lead to gestational thyrotoxicosis. Hyperthyroidism can be treated with propylthiouracil or methimazole and in selected cases, surgical treatment or radioactive iodine can be chosen. In pregnancy, the most used treatment is represented by propylthiouracil which can be used from the first trimester. The aim of this review is to assess the current data regarding the impact of thyroid dysfunction on pregnancy and to synthesize the treatment options during pregnancy and lactation.

The Effect of Thyrotropin-Releasing Hormone and Antithyroid Drugs on Fetal Thyroid Function

A euthyroid pregnant woman will normally have a fetus that displays normal fetal development. However, studies have long demonstrated the role of T3 (Triiodothyronine), T4 (Thyroxine), and TSH (Thyroid Stimulating Hormone) and their degree of penetrability into the fetal circulation. Maternal thyrotropin-releasing hormone (TRH) crosses the placental site and, from mid-gestation onward, is able to promote fetal TSH secretion. Its origin is not only hypothalamic, as was believed until recently. The maternal pancreas, and other extraneural and extrahypothalamic organs, can produce TRH variants, which are transported through the placenta affecting, to a degree, fetal thyroid function. Antithyroid drugs (ATDs) also cross the placenta and, because of their therapeutic actions, can affect fetal thyroid development, leading in some cases to adverse outcomes. Furthermore, there are a number of TRH analogues that share the same properties as the endogenous hormone. Thus, in this narrative review, we highlight the interaction of all the above with fetal growth in uncomplicated pregnancies.

Prognosis of autoimmune thyroid disease associated with hereditary thrombophilia during pregnancy

Autoimmune thyroid pathology has been connected with several systemic autoimmune disorders, namely hereditary thrombophilia and antiphospholipid syndrome. In an iodine-replete country, these diseases need to be evaluated simultaneously. This study was conducted to assess the connection between acute and chronic thyroiditis and inherited thrombophilia and their potential implications in pregnancy. In the analysis of the cases admitted to the Department of Obstetrics Gynecology of the University Emergency Hospital Bucharest from January 2015 up to September 2019, we identified pregnancies marked by autoimmune hypothyroidism and hyperthyroidism associated with hereditary thrombophilia, by standard statistical methods. In this investigation, we determined the prevalence of immunological markers specific for thrombophilia and against thyroid antigens in pregnant women, and explored whether they associate with distinct clinical phenotypes. Besides the well-accounted impact of hereditary thrombophilia during pregnancy - which is emphasized in our study by the incidence of moderate preeclampsia - we also account for a direct and statistically significant relationship between thrombophilia and moderate intensity autoimmune diseases (including autoimmune thyroiditis). Moreover, if these two pathologies are combined there is an increased risk of the presence of another autoimmune disease.

Current controversies in the management of Graves' hyperthyroidism

Introduction: The management of Graves' disease centers on the use of effective and well-established therapies, namely thionamide antithyroid drugs, radioactive iodine, and thyroidectomy. Optimal treatment strategies are however controversial and vary significantly across centers.Areas covered: This review addresses specific controversies in Graves' disease management including the choice of primary therapy, the approach to women planning pregnancy, and optimal strategies for antithyroid drug and radioiodine therapy.Expert opinion: Important considerations in choosing therapy include treatment efficacy, adverse effects, patient convenience, and resource settings. Recent data suggest that early and effective control of hyperthyroidism is key to improving cardiovascular morbidity and mortality. Studies addressing cancer risk in radioiodine-treated patients face methodological challenges and require clarification in appropriately designed studies. Remission rates with antithyroid drugs are comparable when thionamides are used alone (titration-regimen) or in combination with levothyroxine (block and replace) and can be optimized by extending treatment for at least 12-18 months. Fixed and calculated radioiodine activity regimens are both effective but entail a trade-off between convenience and precision in the administered activity. Optimal preconception strategies are still evolving but ablative treatment in advance of pregnancy offers the most pragmatic means of reducing adverse effects of hyperthyroidism in subsequent pregnancy.

Effects of maternal hypothyroidism in the gastrointestinal system of male young offspring from Wistar rats

Alterations in the maternal environment may impact on the fetal development. The objective of this study was to investigate the gastrointestinal consequences of maternal hypothyroidism for the male offspring from Wistar rats. The pregnant rats were divided into three groups: control (C - received water), experimental 1 [E1 - received methimazole (MMI) solution] during gestation and lactation, and experimental 2 (E2 - received MMI solution) during gestation. Maternal parameters evaluated: free T3 and T4, bodyweight variation, and water/food intake. Offspring parameters evaluated: litter size, number of male/female, free T3 and T4, stomach area, gastric ulcer susceptibility, small intestine length and weight, small intestine and distal colon motility, the stomach and intestinal weight-body weight ratio (SW/BW-IW/BW), and the accumulation of intestinal fluid. Maternal T3 and T4 from E1 were decreased when compared to the other groups. There were no differences for maternal water/food intake and weight gain, litter size, and number of males and females. Regarding to offspring, free T3, SW/BW, IW/BW, and intestinal fluid accumulation were not different between the groups, but T4 was decreased in E1. However, 30-day-old pups from E1 and E2 were smaller with lower stomach and small intestine. Even more, E1 presented a lower ulcer index when compared to the C, while E2 had a higher distal colon transit. It can be concluded that maternal hypothyroidism impaired the total body development, as well as gastric and intestinal development, besides interfering with the susceptibility to the ulcer and intestinal transit of male offspring from Wistar rats.

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.

Drug-induced liver injury in pregnancy

Drug intake in pregnant women is common, including prescribed and over-the-counter medications, and herbal medicine and supplements. Drug-induced liver injury (DILI) has become the leading cause of acute liver failure in Western countries, and pregnancy is thought to be a risk factor, but only few anecdotal reports concerning pregnant women are found. These involved antihypertensive, antithyroid, antiretroviral, and antituberculosis medications, and antibiotics. Presentation was usually in the first 20 weeks of gestation following a latency of several weeks, because these drugs were usually prescribed before or in early pregnancy due to their fetal safety. The hepatotoxicity is usually of the idiosyncratic form, and most would resolve spontaneously although occasional liver transplantation and maternal death were reported. The scanty reports could have been related to under-reporting and missed diagnosis due to spontaneous resolution in most cases. DILI should remain one of the differential diagnoses in pregnant women with hepatitis.

An overview of the contribution of acupuncture to thyroid disorders

Thyroid dysfunction, affecting people of all ages, not only damages human growth and energy metabolism but is also comorbid with other illnesses such as cardiovascular disease, kidney disease and gastrointestinal disorders. With the increasing acceptance of alternative and complementary therapies, acupuncture, a traditional Chinese medical practice, has also been employed to address this problem. Analysing 29 clinical projects that were retrieved from 29 major digital databases and include 1757 patients aged 7-79 years from China, Italy, Korea, Macedonia and Russia, this narrative review offers an overview of the efficacy, and evaluated the safe and cost-effective use of acupuncture against hyperthyroidism, hypothyroidism and thyroid-relevant illnesses. Findings indicated reductions in patient symptoms and improvements in biomarkers where acupuncture was used alone or in combination therapy. In addition to showing the role of acupuncture as an alternative and complementary medicine or as an adjunctive therapy for curative and rehabilitative purposes, more well-designed researches are needed to achieve reliable data.

Preconception management of thyroid dysfunction

Uncorrected thyroid dysfunction in pregnancy has well-recognized deleterious effects on foetal and maternal health. The early gestation period is one of the critical foetal vulnerability during which maternal thyroid dysfunction may have lasting repercussions. Accordingly, a pragmatic preconception strategy is key for ensuring optimal thyroid disease outcomes in pregnancy. Preconception planning in women with hypothyroidism should pre-empt and mirror the adaptive changes in the thyroid gland by careful levothyroxine dose adjustments to ensure adequate foetal thyroid hormone delivery in pregnancy. In hyperthyroidism, the goal of preconception therapy is to control hyperthyroidism while curtailing the unwanted side effects of foetal and maternal exposure to antithyroid drugs. Thus, pregnancy should be deferred until a stable euthyroid state is achieved, and definitive therapy with radioiodine or surgery should be considered in women with Graves' disease planning future pregnancy. Women with active disease who are imminently trying to conceive should be switched to propylthiouracil either preconception or at conception in order to minimize the risk of birth defects from carbimazole or methimazole exposure. Optimal strategies for women with borderline states of thyroid dysfunction namely subclinical hypothyroidism, isolated hypothyroxinaemia and thyroid autoimmunity remain uncertain due to the dearth of controlled interventional trials. Future trial designs should aspire to recruit and initiate therapy before conception or as early as possible in pregnancy.

Global epidemiology of hyperthyroidism and hypothyroidism

Thyroid hormones are essential for growth, neuronal development, reproduction and regulation of energy metabolism. Hypothyroidism and hyperthyroidism are common conditions with potentially devastating health consequences that affect all populations worldwide. Iodine nutrition is a key determinant of thyroid disease risk; however, other factors, such as ageing, smoking status, genetic susceptibility, ethnicity, endocrine disruptors and the advent of novel therapeutics, including immune checkpoint inhibitors, also influence thyroid disease epidemiology. In the developed world, the prevalence of undiagnosed thyroid disease is likely falling owing to widespread thyroid function testing and relatively low thresholds for treatment initiation. However, continued vigilance against iodine deficiency remains essential in developed countries, particularly in Europe. In this report, we review the global incidence and prevalence of hyperthyroidism and hypothyroidism, highlighting geographical differences and the effect of environmental factors, such as iodine supplementation, on these data. We also highlight the pressing need for detailed epidemiological surveys of thyroid dysfunction and iodine status in developing countries.

Thyroid Screening in Early Pregnancy: Pros and Cons

Universal thyroid screening in pregnancy is a key debate in thyroidology and obstetrics. It is well-established that thyroid hormones are essential for maintaining pregnancy and optimal fetal development. Thyroid dysfunction is common in women of child-bearing age and also results in substantial adverse obstetric and child neurodevelopmental outcomes. Furthermore, thyroid dysfunction is readily diagnosed with reliable blood tests and easily corrected with inexpensive and available treatments. Screening only high-risk patients appears to miss the majority of cases and economic models show that compared to high-risk screening, universal screening is cost effective even if only overt hypothyroidism was assumed to have adverse obstetric effects. As a result, several countries now implement universal screening. Opponents of universal thyroid screening argue that asymptomatic borderline thyroid abnormalities such as subclinical hypothyroidism and isolated hypothyroxinemia form the bulk of cases of thyroid dysfunction seen in pregnancy and that there is a lack of high quality evidence to support their screening and correction. This review critically appraises the literature, examines the pros and cons of universal thyroid screening using criteria laid down by Wilson and Jungner. It also highlights the growing evidence for universal thyroid screening and indicates the key challenges and practicalities of implementation.

Thyroid disease in pregnancy: new insights in diagnosis and clinical management

Adequate thyroid hormone availability is important for an uncomplicated pregnancy and optimal fetal growth and development. Overt thyroid disease is associated with a wide range of adverse obstetric and child development outcomes. An increasing number of studies now indicate that milder forms of thyroid dysfunction are also associated with these adverse pregnancy outcomes. The definitions of both overt and subclinical thyroid dysfunction have changed considerably over the past few years, as new data indicate that the commonly used fixed upper limits of 2.5 mU/l or 3.0 mU/l for thyroid-stimulating hormone (TSH) are too low to define an abnormal thyroid function. Furthermore, some studies now show that the reference ranges are not necessarily the best cut-off for identifying pregnancies at high risk of adverse outcomes. In addition, data suggest that thyroid peroxidase autoantibody positivity and high or low concentrations of human chorionic gonadotropin seem to have a more prominent role in the interpretation of thyroid dysfunction than previously thought. Data on the effects of thyroid disease treatment are lacking, but some studies indicate that clinicians should be aware of the potential for overtreatment with levothyroxine. Here, we put studies from the past decade on reference ranges for TSH, determinants of thyroid dysfunction, risks of adverse outcomes and options for treatment into perspective. In addition, we provide an overview of the current views on thyroid physiology during pregnancy and discuss strategies to identify high-risk individuals who might benefit from levothyroxine treatment.

A case of severe erythema nodosum induced by methimazole

Erythema nodosum (EN), is the most common variant of septal panniculitis and is possibly a delayed hypersensitivity reaction triggered by a wide range of antigenic stimuli. Hypersensitivity reactions due to medications have been recognized as a cause of 3–10% of EN cases. Case reports of EN associated with the anti-thyroid drugs are quite rarely reported in the literature even if there is a common use of anti-thyroid drugs. We report an EN case due to methimazole. The complaints of patients arose immediately fifteen days after the beginning of methimazole treatment. To the best of our knowledge, this case report is the first of an erythema nodosum induced by methimazole.

Rare NOX3 Variants Confer Susceptibility to Agranulocytosis During Thyrostatic Treatment of Graves' Disease

Agranulocytosis is a rare and serious adverse effect of antithyroid drugs, with unknown etiology. The present study aimed to uncover genetic susceptibility and underlying mechanisms of antithyroid drug-induced agranulocytosis (ATDAC). We studied two independent families with familial Graves' disease, of which several members developed ATDAC. In addition, six sporadic ATDAC patients with Graves' disease were investigated. Whole exome sequencing analysis of affected and unaffected family members was performed to identify genetic susceptibility variants for ATDAC, followed by functional characterization of primary granulocytes from patients and unrelated healthy controls. Whole exome sequencing, cosegregation analysis, and stringent selection criteria of candidate gene variants identified NOX3 as a genetic factor related to ATDAC. Functional studies revealed increased apoptosis of methimazole-treated granulocytes from patients carrying NOX3 variants. In conclusion, genetic variants in NOX3 may confer susceptibility to antithyroid drug-induced apoptosis of granulocytes. These findings contribute to the understanding of the mechanisms underlying ATDAC.

Effects of methimazole and propylthiouracil exposure during pregnancy on the risk of neonatal congenital malformations: A meta-analysis

Objective

The aim of this study was to determine the effect of exposure to different antithyroid drugs during pregnancy on the incidence of neonatal congenital malformations.

Methods

A meta-analysis was performed to compare the incidence of neonatal congenital malformations after exposure to different antithyroid drugs during pregnancy. Twelve studies that met the inclusion criteria were included in this meta-analysis. PubMed, Embase, and CENTRAL databases were searched from inception until January 2017. Study designs included case–control studies, prospective cohort studies, and retrospective cohort studies.

Results

Twelve studies involving 8028 participants with exposure to different antithyroid drugs during pregnancy were included in this study; however, only 10 studies involving 5059 participants involved exposure to different antithyroid drugs exactly during pregnancy. Our results indicated that exposure to methimazole (MMI)/carbimazole (CMZ) only during pregnancy significantly increased the risk of neonatal congenital malformations compared to no antithyroid drug exposure (OR 1.88; 95%CI 1.33 to 2.65; P = 0.0004). No differences were observed between propylthiouracil (PTU) exposure and no antithyroid drug exposure only during pregnancy (OR 0.81; 95%CI 0.58 to 1.15; P = 0.24). Exposure to MMI/CMZ only during pregnancy significantly increased the risk of neonatal congenital malformations compared to that associated with exposure to PTU (OR 1.90; 95%CI 1.30 to 2.78; P = 0.001).

Conclusion

For pregnant women with hyperthyroidism, exposure to MMI/CMZ significantly increased the incidence of neonatal congenital malformations compared to exposure to PTU and no antithyroid drug exposure; however, no differences were observed between PTU exposure and no antithyroid drug exposure.

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.

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.

Graves' Disease Pharmacotherapy in Women of Reproductive Age

Graves' disease is an autoimmune disorder in which inappropriate stimulation of the thyroid gland results in unregulated secretion of thyroid hormones resulting in hyperthyroidism. Graves' disease is the most common cause of autoimmune hyperthyroidism during pregnancy. Treatment options for Graves' disease include thioamide therapy, partial or total thyroidectomy, and radioactive iodine. In this article, we review guideline recommendations for Graves' disease treatment in women of reproductive age including the recent guideline from the American College of Obstetricians and Gynecologists. Controversy regarding appropriate thioamide therapy before, during, and after pregnancy is reviewed. Surgical and radioactive iodine therapy considerations in this patient population are also reviewed. In patients who may find themselves pregnant during therapy or develop Graves' disease during their pregnancy, consideration should be given to the most appropriate treatment course for the mother and fetus. Thioamide therapy should be used with either propylthiouracil or methimazole at appropriate doses that target the upper range of normal to slightly hyperthyroid to avoid creating hypothyroidism in the fetus. Consideration should also be given to the adverse effects of thioamide, such as agranulocytosis and hepatotoxicity, with appropriate patient consultation regarding signs and symptoms. Individuals who wish to breastfeed their infants while taking thioamide should receive the lowest effective dose. Surgery should be reserved for extreme cases and limited to the second trimester, if possible. Radioactive iodine therapy may be used in nonpregnant individuals, with limited harm to future fertility. Radioactive iodine therapy should be withheld in pregnant women and those who are actively breastfeeding. Clinicians should keep abreast of developments in clinical trials and evidence-based recommendations regarding Graves' disease in reproductive-age women for any changes in evidence-based practice.

Current trends in antithyroid drug treatment of Graves' disease

INTRODUCTION

Graves' hyperthyroidism is associated with significant morbidity and mortality risk. The thionamides, methimazole, its pro-drug derivative carbimazole, and propylthiouracil, remain a cornerstone of management. Yet despite decades of use, optimal strategies for maximising treatment response and curtailing adverse effect risk remains uncertain.

AREAS COVERED

We reviewed the current literature on the evidence based medical management of Graves' disease. Specifically, we evaluated current approaches to the use of thionamides, adjunctive therapies, and potential novel agents for controlling Graves' hyperthyroidism.

EXPERT OPINION

Primary medical therapy is successful in less than 50% of cases and so careful selection of patients for medical treatment based on a combination of pathological and pragmatic considerations is essential. Carbimazole or methimazole is the treatment of choice in the non-pregnant population driven by its more favourable pharmacokinetic and adverse effect profile over propylthiouracil. In pregnancy the choice of treatment is less straightforward and an approach that minimises undue fetal exposure to all thionamides should be adopted. Additional data is needed on the value of adjunctive therapies including potassium perchlorate, iodides, glucocorticoids, lithium, and cholestyramine. Novel agents directed against pathogenetic targets including TSH receptor blocking monoclonal antibodies and small molecule antagonists may hold promise for the future.

Antithyroid Drug Use in Pregnancy and Birth Defects: Why Some Studies Find Clear Associations, and Some Studies Report None

BACKGROUND

Rare cases of birth defects after the use of methimazole (MMI) or carbimazole to treat hyperthyroidism in early pregnancy have been reported since 1972, whereas propylthiouracil (PTU) has not been considered teratogenic. Recently, two studies reported birth defects after the use of MMI in early pregnancy to affect 2-4% of exposed children, and one study also found birth defects after the use of PTU. On the other hand, some published studies did not find associations between the use of thionamides and birth defects.

SUMMARY

The methods used in the two positive and the four negative reports are reviewed. The two positive studies included a sufficient number of children exposed to MMI (n = 1231 and 1097) to evaluate the studied outcomes, whereas the four negative studies included a much lower number of exposed children (n = 73, 108, 30, and 124). Considering PTU, the birth defects observed in one study were in general milder and tended to be diagnosed and registered only when they resulted in complications and led to surgery after one year of age. None of the negative studies has investigated outcomes after one year of age.

CONCLUSION

Studies finding no associations between early pregnancy exposure to antithyroid drugs and birth defects were either not sufficiently powered or did not study outcomes at optimal ages.

Substituting Potassium Iodide for Methimazole as the Treatment for Graves' Disease During the First Trimester May Reduce the Incidence of Congenital Anomalies: A Retrospective Study at a Single Medical Institution in Japan

BACKGROUND

To control hyperthyroidism due to Graves' disease, antithyroid drugs should be administered. Several studies have shown that exposure to methimazole (MMI) during the first trimester of pregnancy increases the incidence of specific congenital anomalies that are collectively referred to as MMI embryopathy. Congenital anomalies associated with exposure to propylthiouracil (PTU) have also recently been reported.

METHODS

This study investigated whether substituting potassium iodide (KI) for MMI in the first trimester would result in a lower incidence of major congenital anomalies than continuing treatment with MMI alone. The cases of 283 women with Graves' disease (GD) were reviewed whose treatment was switched from MMI to KI in the first trimester (iodine group), as well as the cases of 1333 patients treated with MMI alone (MMI group) for comparison. Another major outcome of interest was the incidence of neonatal thyroid dysfunction. The subjects of the analysis of major congenital anomalies and neonatal thyroid dysfunction were live-born infants.

RESULTS

The incidence of major anomalies was 4/260 (1.53%) in the iodine group, which was significantly lower than the incidence of 47/1134 (4.14%) in the MMI group. Two neonates in the iodine group had anomalies consistent with MMI embryopathy (0.8%), as opposed to 18 neonates in the MMI group (1.6%). None of the neonates exposed to KI had thyroid dysfunction or goiter.

CONCLUSIONS

Substituting KI for MMI as a means of controlling hyperthyroidism in GD patients during the first trimester may reduce the incidence of congenital anomalies, at least in iodine-sufficient regions.

Should All Women Be Screened for Thyroid Dysfunction in Pregnancy?

The subject of universal thyroid screening in pregnancy generates impassioned debate. Thyroid dysfunction is common, has significant adverse implications for fetal and maternal well-being, is readily detectable and can be effectively and inexpensively treated. Furthermore, the currently recommended case-finding strategy does not identify a substantially proportion of women with thyroid dysfunction thus favoring universal screening. On the other hand subclinical thyroid dysfunction forms the bulk of gestational thyroid disorders and the paucity of high-level evidence to support correction of these asymptomatic biochemical abnormalities weighs against universal screening. This review critically appraises the literature, examines the pros and cons of universal thyroid screening in pregnancy, highlighting the now strong case for implementing universal screening and explores strategies for its implementation.

Rethinking antithyroid drugs in pregnancy

Uncontrolled hyperthyroidism in pregnancy poses a risk to both mother and foetus, and the optimal treatment strategy in this setting remains elusive. Instigation of pharmacological therapy or an alternative intervention during pregnancy requires careful consideration, and the evidence that has underpinned our choice of antithyroid drug has not been robust. Recent research developments have prompted us to question our practice, and reconsider our approach to managing this patient group.

Severity of birth defects after propylthiouracil exposure in early pregnancy

BACKGROUND

Propylthiouracil (PTU) used in the treatment of maternal hyperthyroidism in early pregnancy may be associated with a higher prevalence of birth defects in the face and neck region and in the urinary system but the severity of these complications remains to be elucidated.

METHODS

Review of hospital-registered cases of birth defects in the face and neck region and in the urinary system after PTU exposure in early pregnancy. We obtained information on maternal redeemed prescription of PTU and child diagnosis of birth defect from nationwide registers for all children born in Denmark between 1996 and 2008 (n=817,093). The children were followed until December 31, 2010 (median age, 8.3 years) and the Cox proportional hazards model was used to estimate adjusted hazard ratio (HR) with 95% confidence interval (CI) for having a birth defect after PTU exposure versus nonexposed children (n=811,730).

RESULTS

Fourteen cases of birth defects were identified in the face and neck region and in the urinary system after PTU exposure in early pregnancy; 11 children were exposed to PTU only (n=564), whereas 3 children were born to mothers who switched from methimazole (MMI)/carbimazole (CMZ) to PTU in early pregnancy (n=159). Among children exposed to PTU only, the adjusted HR for having a birth defect in the face and neck region was 4.92 (95% CI 2.04-11.86) and in the urinary system 2.73 (1.22-6.07). Looking into details of the 14 cases, 7 children were diagnosed with a birth defect in the face and neck region (preauricular and branchial sinus/fistula/cyst) and 7 children had a birth defect in the urinary system (single cyst of kidney and hydronephrosis). Surgical treatment was registered in 6 of the cases with a birth defect in the face and neck region and 3 of the cases with a birth defect in the urinary system. Two of the children with a birth defect in the urinary system also had other birth defects (genital organs).

CONCLUSIONS

We report details on possible PTU-associated birth defects. They tend to be less severe than the defects observed after MMI/CMZ exposure. Yet, the majority of affected children had to undergo surgery.

Therapy of endocrine disease: antithyroid drug use in early pregnancy and birth defects: time windows of relative safety and high risk?

BACKGROUND

Antithyroid drugs (ATDs) may have teratogenic effects when used in early pregnancy.

OBJECTIVE

To review the association between the time period of ATD exposure in early pregnancy and the development of birth defects.

METHODS

We identified publications on birth defects after early pregnancy exposure to the ATDs methimazole (MMI; and its prodrug carbimazole (CMZ)) and propylthiouracil (PTU). Cases of birth defects after ATD treatment had been initiated or terminated within the first 10 weeks of pregnancy were identified and studied in detail.

RESULTS

A total of 92 publications were read in detail. Two recent large controlled studies showed ATD-associated birth defects in 2-3% of exposed children, and MMI/CMZ-associated defects were often severe. Out of the total number of publications, 17 included cases of birth defects with early pregnancy stop/start of ATD treatment, and these cases suggested that the high risk was confined to gestational weeks 6-10, which is the major period of organogenesis. Thus, the cases reported suggest that the risk of birth defects could be minimized if pregnant women terminate ATD intake before gestational week 6.

CONCLUSION

Both MMI and PTU use in early pregnancy may lead to birth defects in 2-3% of the exposed children. MMI-associated defects are often severe. Proposals are given on how to minimize the risk of birth defects in fertile women treated for hyperthyroidism with ATDs.

Frequency of Adverse Events of Antithyroid Drugs Administered during Pregnancy

The frequency and types of adverse events after initial antithyroid drug (ATD) therapy during pregnancy have never been reported, nor has whether the frequency of adverse events is the same as among nonpregnant subjects ever been investigated. We investigated retrospectively the frequency of adverse events after initial ATD administration to previously untreated Graves' disease (GD) patients during pregnancy. We reviewed the charts of cases of 91 untreated pregnant women who came to our hospital for the first time and were newly diagnosed with GD during the period between January 1, 1999, and December 31, 2011. Thiamazole (MMI) was used to treat 40 patients and 51 patients were treated with propylthiouracil (PTU). Adverse events occurred in 5 patients (5/40; 12.5%) treated with MMI, and they consisted of cutaneous reactions in 5 patients. Adverse events occurred in five patients (5/51; 9.8%) treated with PTU, and they consisted of hepatotoxicity in two patients and cutaneous reactions in three patients. No patients experienced agranulocytosis or ANCA-related vasculitis. Comparison with the expected rate of adverse events in nonpregnant individuals showed that the frequency of adverse events in pregnant individuals was low.

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.