Thyroid disorders of neonates born to mothers with Graves' disease

Thyroid function and thyroid disorders during pregnancy: a review and care pathway

PURPOSE

To review the literature on thyroid function and thyroid disorders during pregnancy.

METHODS

A detailed literature research on MEDLINE, Cochrane library, EMBASE, NLH, ClinicalTrials.gov, and Google Scholar databases was done up to January 2018 with restriction to English language about articles regarding thyroid diseases and pregnancy.

RESULTS

Thyroid hormone deficiencies are known to be detrimental for the development of the fetus. In particular, the function of the central nervous system might be impaired, causing low intelligence quotient, and mental retardation. Overt and subclinical dysfunctions of the thyroid disease should be treated appropriately in pregnancy, aiming to maintain euthyroidism. Thyroxine (T4) replacement therapy should reduce thyrotropin (TSH) concentration to the recently suggested fixed upper limits of 2.5 mU/l (first and second trimester) and 3.0 mU/l (third trimester). Overt hyperthyroidism during pregnancy is relatively uncommon but needs prompt treatment due to the increased risk of preterm delivery, congenital malformations, and fetal death. The use of antithyroid drug (methimazole, propylthiouracil, carbimazole) is the first choice for treating overt hyperthyroidism, although they are not free of side effects. Subclinical hyperthyroidism tends to be asymptomatic and no pharmacological treatment is usually needed. Gestational transient hyperthyroidism is a self-limited non-autoimmune form of hyperthyroidism with negative antibody against TSH receptors, that is related to hCG-induced thyroid hormone secretion. The vast majority of these patients does not require antithyroid therapy, although administration of low doses of β-blocker may by useful in very symptomatic patients.

CONCLUSIONS

Normal maternal thyroid function is essential in pregnancy to avoid adverse maternal and fetal outcomes.

[Recommendations for the diagnosis and follow up of the foetus and newborn child born to mothers with autoimmune thyroid disease]

The objective of this document is to review the current recommendations in the management of the foetus and the newborn child born to mothers with autoimmune thyroid disease. In 2017, the American Thyroid Association published guidelines for the diagnosis and management of thyroid disease during pregnancy and post-partum. In this guide, 97 recommendations were made, and an algorithm for the diagnosis and treatment of gestational hypothyroidism was proposed. Also, in this last year, a wide review was been published on the foetal and neonatal approach of the child of a mother with Graves' disease. The importance of the determination of maternal antibodies against thyrotropin receptor in the second half of pregnancy is stressed, in order to adequately stratify the risk in the neonate.

Secondary and tertiary preventions of thyroid disease

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Neonatal Graves' Disease with Maternal Hypothyroidism

Neonatal Graves' disease presenting as conjugated hyperbilirubinemia is a diagnostic challenge because the differential includes a gamut of liver and systemic diseases. We present a unique case of neonatal Graves' disease in a premature infant with conjugated hyperbilirubinemia born to a mother with hypothyroidism during pregnancy and remote history of Graves' disease. Infant was treated with a combination of methimazole, propranolol, and potassium iodide for 4 weeks. Thyroid function improved after 8 weeks of treatment with full recovery of thyroid function, disappearance of thyroid-stimulating antibodies, and resolution of failure to thrive and conjugated hyperbilirubinemia. This case provides several clinical vignettes as it is a rare, severe, presentation of an uncommon neonatal disease, signs, symptoms, and clinical history presented a diagnostic challenge for neonatologists and endocrinologists, normal newborn screen was misleading, and yet timely treatment led to a full recovery.

Fetal neonatal hyperthyroidism: diagnostic and therapeutic approachment

Fetal and neonatal hyperthyroidism may occur in mothers with Graves' disease. Fetal thyrotoxicosis manifestation is observed with the transition of TSH receptor stimulating antibodies to the fetus from the 17th-20th weeks of pregnancy and with the fetal TSH receptors becoming responsive after 20 weeks. The diagnosis is confirmed by fetal tachycardia, goiter and bone age advancement in pregnancy and maternal treatment is conducted in accordance. The probability of neonatal hyperthyroidism is high in the babies of mothers that have ongoing antithyroid requirement and higher antibody levels in the last months of pregnancy. Clinical manifestation may be delayed by 7-17 days because of the antithyroid drugs taken by the mother. Neonatal hyperthyroidism symptoms can be confused with sepsis and congenital viral infections. Herein, the diagnosis and therapeutic approach are reviewed in cases of fetal neonatal hyperthyroidism.

Management of Neonates Born to Mothers With Graves' Disease

Neonates born to mothers with Graves' disease are at risk for significant morbidity and mortality and need to be appropriately identified and managed. Because no consensus guidelines regarding the treatment of these newborns exist, we sought to generate a literature-based management algorithm. The suggestions include the following: (1) Base initial risk assessment on maternal thyroid stimulating hormone (TSH) receptor antibodies. If levels are negative, no specific neonatal follow-up is necessary; if unavailable or positive, regard the newborn as "at risk" for the development of hyperthyroidism. (2) Determine levels of TSH-receptor antibodies in cord blood, or as soon as possible thereafter, so that newborns with negative antibodies can be discharged from follow-up. (3) Measurement of cord TSH and fT4 levels is not indicated. (4) Perform fT4 and TSH levels at day 3 to 5 of life, repeat at day 10 to 14 of life and follow clinically until 2 to 3 months of life. (5) Use the same testing schedule in neonates born to mothers with treated or untreated Graves' disease. (6) When warranted, use methimazole (MMI) as the treatment of choice; β-blockers can be added for sympathetic hyperactivity. In refractory cases, potassium iodide may be used in conjunction with MMI. The need for treatment of asymptomatic infants with biochemical hyperthyroidism is uncertain. (7) Assess the MMI-treated newborn on a weekly basis until stable, then every 1 to 2 weeks, with a decrease of MMI (and other medications) as tolerated. MMI treatment duration is most commonly 1 to 2 months. (8) Be cognizant that central or primary hypothyroidism can occur in these newborns.

Neonatal Cholestasis Caused by Undiagnosed Maternal Graves' Disease

Neonatal cholestasis results from a variety of etiologies, including anatomic, infectious, and metabolic abnormalities. Hyperthyroidism, in contrast to hypothyroidism, is infrequently associated with neonatal cholestasis. Newborn screening is an important tool to detect newborn metabolic disorders, including thyroid dysfunction. However, one must exercise caution when interpreting these reports; typically only high thyroid stimulating hormone (TSH) levels are flagged as abnormal, while low or undetectable levels may not be. We present a unique case of cholestasis in a hyperthyroid neonate of an untreated, undiagnosed mother with Graves' disease; the infant's metabolic screen was not flagged as abnormal.

Screening strategies for thyroid disorders in the first and second trimester of pregnancy in China

BACKGROUND

Thyroid dysfunction during pregnancy is associated with multiple adverse outcomes, but whether all women should be screened for thyroid disorders during pregnancy remains controversial.

OBJECTIVE

To evaluate the effectiveness of the targeted high risk case-finding approach for identifying women with thyroid dysfunction during the first and second trimesters of pregnancy.

METHODS

Levels of thyroid stimulating hormone (TSH), free thyroxine (FT4), and thyroid peroxidase antibodies (TPOAb) were measured in 3882 Chinese women during the first and second trimester of pregnancy. All tested women were divided into the high risk or non-high risk groups, based on their history, findings from physical examination, or other clinical features suggestive of a thyroid disorder. Diagnosis of thyroid disorders was made according to the standard trimester-specific reference intervals. The prevalence of thyroid disorders in each group was determined, and the feasibility of a screening approach focusing exclusively on high risk women was evaluated to estimate the ability of finding women with thyroid dysfunction.

RESULTS

The prevalence of overt hypothyroidism or hyperthyroidism in the high risk group was higher than in the non-high risk group during the first trimester (0.8% vs 0, χ2 = 7.10, p = 0.008; 1.6% vs 0.2%, χ2 = 7.02, p = 0.008, respectively). The prevalence of hypothyroxinemia or TPOAb positivity was significantly higher in the high risk group than in the non-high risk group during the second trimester (1.3% vs 0.5%, χ2 = 4.49, p = 0.034; 11.6% vs 8.4%, χ2 = 6.396, p = 0.011, respectively). The total prevalence of hypothyroidism or hyperthyroidism and the prevalence of subclinical hypothyroidism or hyperthyroidism were not statistically different between the high risk and non-high risk groups, for either the first or second trimester.

CONCLUSION

The high risk screening strategy failed to detect the majority of pregnant women with thyroid disorders. Therefore, we recommend universal screening of sTSH, FT4, and TPOAb during the first trimester and second trimester of pregnancy.

[Maternal autoimmune thyroid disease: relevance for the newborn]

BACKGROUND AND OBJECTIVE

Autoimmune thyroid disease is amongst the most frequent endocrine disorders during pregnancy. It is associated with an increase in perinatal morbidity, congenital defects, neurological damage, fetal and neonatal thyroid dysfunction. Maternal thyroid hormones play a key role in child neurodevelopment. We aimed to evaluate the thyroid function and the clinical course of neonates born from mothers with autoimmune thyroid disease during the first months of life in order to define the follow-up.

PATIENTS AND METHOD

We monitored thyroid function and clinical status during the first months in 81 newborns of mothers with autoimmune thyroid disease; 16 had Graves disease and 65 autoimmune thyroiditis.

RESULTS

A percentage of 4.93 newborns had congenital defects, and 8.64% neonates showed an increase in thyrotropin (TSH) (>9.5 μUI/mL 2 times) and required thyroxin within the first month of life. A 85.7% of these showed a negative newborn screening (due to a later increase of TSH). A higher TSH value in the newborn was related to an older age of the mother, higher levels of thyroid peroxidase (TPO) antibody during pregnancy and lower birth weight. A higher free thyroxine (FT4) value in the newborn was related to fewer days of life and mothers with Graves disease.

CONCLUSIONS

We recommend the evaluation of TSH, T4 and TPO antibodies before 10 weeks in all pregnant women with follow-up if maternal thyroid autoimmunity or disorders is detected. It is also recommended to test children's serum TSH and FT4 at 48 h of life in newborns of mothers with autoimmune thyroid disease and repeat them between the 2nd and 4th week in children with TSH>6 μUI/mL. Careful endocrine follow-up is advised in pregnant women and children if hyperthyroidism is detected.

Management of hyperthyroidism during pregnancy in Asia

Maternal hyperthyroidism in pregnancy is associated with adverse impacts on both mother and fetus. Recently, the American Thyroid Association and the Endocrine Society have published guidelines for the management of thyroid diseases in pregnancy. We aimed to disclose the impact of these guidelines in current practices of Asian members of the Asia-Oceania Thyroid Association (AOTA) regarding the management of hyperthyroidism in pregnancy. Completed questionnaire survey, based on clinical case scenarios, was collected from 321 Asian physician members of AOTA from 21 Asian countries in 2013. For a woman with Graves' disease planning pregnancy, 92% of clinicians favored antithyroid treatment, 52% with propylthiouracil (PTU) while 40% preferred methimazole (MMI). For a pregnant woman with newly diagnosed overt hyperthyroidism, nearly all responders initiated PTU treatment. To monitor dosage of antithyroid drugs, approximately 73% of responders used TSH and free T4 (FT4) levels without free T3 (FT3) (53%) or with FT3 (20%). Majority of responders targeted achieving low serum TSH with FT4 (or total T4) in the upper end of the normal range. For management of gestational thyrotoxicosis, 40% chose to follow up and 52% treated patients with PTU. Although timing of TSH receptor antibodies measurement in pregnant hyperthyroid patients was variable, 53% of responders would check it at least once during pregnancy. Nearly 80% of responders do not treat subclinical hyperthyroidism in pregnancy. Therefore, despite wide variations in the management of hyperthyroidism during pregnancy in Asia, majority of Asian physicians practice within the recommendations of major professional societies.

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

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

Accumulation and endocrine disrupting effects of the flame retardant mixture Firemaster® 550 in rats: an exploratory assessment

Firemaster® 550 (FM 550), a fire-retardant mixture used in foam-based products, was recently identified as a common contaminant in household dust. The chemical structures of its principle components suggest they have endocrine disrupting activity, but nothing is known about their physiological effects at environmentally relevant exposure levels. The goal of this exploratory study was to evaluate accumulation, metabolism and endocrine disrupting effects of FM 550 in rats exposed to 100 or 1000 µg/day across gestation and lactation. FM 550 components accumulated in tissues of exposed dams and offspring and induced phenotypic hallmarks associated with metabolic syndrome in the offspring. Effects included increased serum thyroxine levels and reduced hepatic carboxylesterease activity in dams, and advanced female puberty, weight gain, male cardiac hypertrophy, and altered exploratory behaviors in offspring. Results of this study are the first to implicate FM 550 as an endocrine disruptor and an obesogen at environmentally relevant levels.

Hyperthyroidism in pregnancy

PURPOSE OF REVIEW

Successful outcome in pregnancy hyperthyroidism depends on the cause, interpretation of laboratory tests, and careful use of antithyroid drug (ATD) therapy. Planning of a pregnancy in a woman with active or past history of Graves' hyperthyroidism is mandatory in order to avoid complications.

RECENT FINDINGS

Fetal health may be affected by three factors: poor control of maternal hyperthyroidism, titer of maternal TRAb, and inappropriate use of ATD. Careful assessment of thyroid function through pregnancy and evaluation of fetal development by ultrasonography is the cornerstone for a successful outcome. In a subgroup of women previously treated with ablation therapy, those whose serum TSRAb titers remained elevated, are at risk of having a fetus/neonate with Graves' hyperthyroidism. Use of ATD during lactation is well tolerated, if recommended guidelines are followed.

SUMMARY

Women during their childbearing age with active Graves' hyperthyroidism should plan their pregnancy. Causes of hyperthyroidism in pregnancy include Graves' disease or autonomous adenoma, and transient gestational thyrotoxicosis as a consequence of excessive production of human chroionic gonadotropin by the placenta. Careful interpretation of thyroid function tests and frequent adjustment of ATD is of utmost importance in the outcome of pregnancy. Graves' hyperthyroidism may relapse early in pregnancy or at the end of the first year postpartum.

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

OBJECTIVE

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

EVIDENCE

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

CONSENSUS PROCESS

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

CONCLUSIONS

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

Thyroid disorders in pregnancy

Maternal hypothyroidism, thyroid antibody positivity, and hyperthyroidism may pose significant risks in terms of pregnancy complications and fetal adverse effects. Treatment of hyperthyroidism with thionamides remains the standard of care during pregnancy. Radioiodine use is contraindicated in pregnancy, including in the treatment of thyroid carcinoma, because of the risk of fetal hypothyroidism, subsequent cognitive impairment, and even fetal death. Normal thyroid function during pregnancy is essential to ensure delivery, to the best extent possible, of a healthy baby, which may be achieved with frequent monitoring of thyroid function during gestation and cautious adjustment of medications during treatment.