Management of neonates born to women with Graves' disease: a cohort study

Third-Generation Thyrotropin Receptor Antibody (TRAb) assay for predicting neonatal thyroid dysfunction in pregnant women with Graves' disease

PURPOSE

The aim is to validate the third generation Thyrotropin receptor antibody (TRAb) assay for predicting neonatal thyroid dysfunction and adverse pregnancy outcomes in pregnant women with Graves' disease.

METHODS

This prospective cohort study was conducted in TRAb positive pregnant women with Graves' disease and their off springs. The primary outcome was to assess different forms of neonatal thyroid dysfunction in relation to maternal and neonatal TRAb levels. The secondary outcome was to predict adverse pregnancy outcomes by using maternal TRAb levels. Serum T3, FT4, TSH, TRAb levels were measured using electrochemiluminescence immunoassay.

RESULTS

51 pregnant women were included. Five women had adverse pregnancy outcomes, TRAb levels of > 19.06 IU/L (10.9 times the upper limit of normal (ULN)) predicted adverse pregnancy outcomes with 100% sensitivity and 93.5% specificity. Among the 46 successful live births, 13 (28.3%) had neonatal thyroid dysfunction. Out of 13 neonates, 7 (32%) had neonatal thyrotoxicosis, 4 (18%) had primary hypothyroidism, and 2 (9%) had central hypothyroidism. Third trimester maternal TRAb levels of > 7.99 IU/L (4.6 times the ULN)and day three neonatal TRAb levels of > 5.03 IU/L (2.9 times the ULN), predicted the neonatal thyrotoxicosis with 100% sensitivity and 97.4% specificity.

CONCLUSION

Very high maternal third generation TRAb levels strongly predicted the adverse pregnancy outcomes and neonatal thyroid dysfunction in pregnant women with Graves' disease. Neonatal thyroid function test along with the TRAb levels strongly correlated with different forms of neonatal thyroid dysfunction and is very useful in avoiding inadvertent treatment to neonates.

[Commentary on the latest DGN procedure guidelines for radioiodine therapy for benign thyroid diseases]

Die aktuelle DGN-Handlungsempfehlung behandelt das Thema der Entwicklung der TRAK-Spiegel nach der Radiojodtherapie der Immunhyperthyreose erstmals im Vergleich zu den vorangehenden Versionen. Diese neuen Hinweise sollten differenziert eingeordnet und anschließend dem Patienten z.B. in den Aufklärungsunterlagen geeignet zugänglich gemacht werden. Bei der Verwendung fertiger kommerzieller Aufklärungsbögen, herausgegeben von einigen medizinisch orientierten Verlagsgesellschaften, ist auf deren Aktualität zu achten, ggf. sind die noch nicht berücksichtigten Aspekte im Einzelfall handschriftlich nachzutragen. Die Verwendung eigener klinikinterner Aufklärungsblätter zur Radiojodtherapie gutartiger Schilddrüsenerkrankungen bietet den Vorteil, dass neue Aspekte durch den behandelnden Nuklearmediziner selbst eingefügt werden können.

Antithyroid Drugs in the Management of Graves' Disease: A Friend and Foe

Graves' disease is an autoimmune condition in which the patient develops autoantibodies that stimulate the thyroid gland, leading to thyrotoxicosis. We report the case of a 29-year-old female who presented one month postpartum with typical symptoms and signs of thyrotoxicosis. Biochemical and radiological investigations confirmed thyrotoxicosis due to Graves' disease. She received methimazole (MMI) treatment, leading to an allergic reaction in the form of a generalized rash on the body precluding its use. We later started the treatment with propylthiouracil, which she initially tolerated well. During her treatment, she became pregnant and delivered a baby girl by cesarean section at 37 weeks of gestation. The baby developed neonatal thyrotoxicosis due to the transplacental transmission of maternal thyrotropin receptor antibodies. Thyrotoxicosis was short-lived, without consequences, and treated with antithyroid drugs. Three months after delivery, thyroid hormone levels rose considerably, requiring higher doses of propylthiouracil, which resulted in severe hepatic dysfunction, and therefore we stopped the therapy. We admitted her to the hospital for rapid correction of thyroid hormones using steroids, supersaturated potassium iodide, and cholestyramine before she underwent a total thyroidectomy. Our case highlights the challenges the patients and clinicians can face while managing Graves' disease. We discuss the role of a multidisciplinary team approach to care and the options available for treatment in such difficult situations.

Incidence of and Risk Factors for Neonatal Hypothyroidism Among Women with Graves' Disease Treated with Antithyroid Drugs Until Delivery

Background: The incidence of neonatal hypothyroidism among newborns born to mothers with Graves' disease (GD) who continued antithyroid drug (ATD) treatment until delivery has never been reported. Objective: Our primary objective was to investigate the incidence of neonatal hypothyroidism among newborns born to mothers with GD who were treated with ATD until delivery. Our secondary objective was to identify the cutoff ATD daily doses for neonatal hypothyroidism risk, based on maternal thyrotropin (TSH) receptor antibody (TRAb) levels. Methods: We conducted a retrospective cohort study. We included 305 pregnant women with GD who were treated with an ATD until delivery (63 treated with methimazole [MMI] and 242 treated with propylthiouracil [PTU]). Umbilical cord TSH, free thyroxine (fT4), and TRAb levels were measured at delivery, and we investigated the respective relationships between neonatal hypothyroidism at delivery and maternal fT4 levels, TRAb levels, and daily ATD doses during pregnancy. Neonatal hypothyroidism was diagnosed when the umbilical cord fT4 level was below the lower limit of the reference range. Results: The incidence of neonatal hypothyroidism at delivery was 19.0% ([confidence interval, CI, 11.2-30.4]; 12/63) in the MMI group and 12.8% ([CI, 9.2-17.6]; 31/242) in the PTU group. Neonatal goiter was observed in one neonate in the PTU group, and two infants in the PTU group required levothyroxine treatment. The daily ATD dose in the third trimester was the strongest predictor of neonatal hypothyroidism at delivery; the cutoff MMI dose was 10 mg/day, and the cutoff PTU dose was 150 mg/day. When the maternal TRAb level in the third trimester was above three times the upper limit of the normal range, the cutoff MMI dose was 20 mg/day, and the cutoff PTU dose was 150 mg/day. Conclusions: Maternal fT4 and TRAb levels were higher in the neonatal hypothyroid group, which suggested prolonged GD activity. Careful follow-up is necessary when maternal GD remains active and the ATD dose to control maternal thyrotoxicosis cannot be reduced.

A prospective study among neonates born to mothers with active or past Graves disease

OBJECTIVE

The aim of this prospective study was to describe demographic and clinical characteristics of neonates born to mothers with active or past Graves disease and to assess compliance since implementation of a new protocol in our center.

METHODS

We prospectively followed up neonates born to mothers with active or past Graves disease in a tertiary hospital in Spain between August 2019 and September 2021 according to our protocol. We reviewed maternal and neonatal history of these neonates, and we followed up newborns at risk of neonatal hyperthyroidism.

RESULTS

Among 5808 births, 33 neonates were born to mothers with active or past Graves disease (0.57%). Six mothers (18.2%) had positive levels of thyroid-stimulating hormone receptor antibodies during pregnancy and five mothers (15.1%) between weeks 20 and 24 of pregnancy. Two of them had received definitive therapy for Graves disease before pregnancy. Two neonates (7.1%) were at high risk of neonatal hyperthyroidism and were followed-up until two months, without hyperthyroidism signs or abnormal thyroid hormone levels. Compliance of protocol during pregnancy was 84.9% and 75.8% at birth.

CONCLUSIONS

Prevalence of Graves disease among pregnant women was 0.57%, with no cases of neonatal hyperthyroidism. Compliance of protocol was adequate during pregnancy (84.9%) and acceptable at birth (75.8%).

Thyroid function, thyroid antibodies and early postnatal development in neonates of mothers with thyroid disorders

BACKGROUND

Thyroid dysfunction during pregnancy is relatively common and can cause obstetric complications and significantly influence fetal development.

AIMS

We aimed to evaluate postnatal clinical and laboratory characteristics in the first days of life in infants born to mothers with a thyroid disorder.

STUDY DESIGN AND SUBJECTS

We conducted a retrospective single-center study with neonates born between January 2010 and May 2020. Early laboratory parameters and clinical findings in neonates of mothers with different maternal thyroid disorders were analysed.

RESULTS

We included 314 newborns of mothers with Hashimoto's thyroiditis, 171 with non-Hashimoto's hypothyroidism, 42 with Graves' disease, 12 with non-Graves' hyperthyroidism, and 190 neonates born to mothers without thyroid dysfunction. No demographic, clinical, and laboratory differences were observed between neonates from mothers with a thyroid disorder and healthy mothers. FT3 and fT4 correlated positively with gestational age (p < 0.001; p < 0.001) and negatively with maximum postnatal weight loss (p = 0.043; p < 0.001). High fT3 values were associated with lower maximum bilirubin levels (p = 0.020).

CONCLUSION

Despite an increased morbidity risk due to the transplacental exposure to maternal antibodies, most neonates born to mothers with thyroid disorders show normal postnatal development and thyroid function tests during the first days of life.

Neonatal Screening for Hyperthyroidism Proof of Concept

CONTEXT

Early treatment is essential to avoid the cardiac complication of neonatal hyperthyroidism (NH). Our results have direct implications for clinical care.

OBJECTIVE

NH can cause potentially fatal neonatal thyrotoxicosis. Here, we have evaluated the feasibility of neonatal hyperthyroidism screening using the thyroid-stimulating hormone value in dried blood collected routinely on filter paper on the third postnatal day of life for congenital hypothyroidism screening.

METHODS

Retrospective case-control study. Cases were identified using data from our previously published study of 280 000 infants born in 10 maternity units in France in 2007-2014. Controls were identified among the 1 362 564 infants born in the Ile-de-France region during the same period.

RESULTS

A screening thyroid-stimulating hormone level below 0.18 mIU/L on the third postnatal day had 71% (95% CI 44-90%) sensitivity, 99% (95% CI 99-100%) specificity, 81% (95% CI 74-86%) positive predictive value, and 98% (95% CI 97-99%) negative predictive value for detecting severe NH. By univariate regression analysis, the screening thyroid-stimulating hormone value was the strongest predictor of NH (P < .00001), with an area under the receiver-operating characteristics curve of 0.98 (95% CI 0.95-1.0). Expected frequencies were not significantly different from observed frequencies (Hosmer-Lemeshow test, P = .99).

CONCLUSION

The screening thyroid-stimulating hormone test can be used to detect severe NH, the optimal cut-off being 0.18 mIU/L. The additional cost compared with screening for congenital hypothyroidism would be small. Infants with neonatal hyperthyroidism would benefit from an earlier diagnosis with treatment initiation at the presymptomatic stage in many cases, ensuring optimal outcomes.

Fetal and Neonatal Thyroid Dysfunction

Fetal and neonatal dysfunctions include rare serious disorders involving abnormal thyroid function during the second half of gestation, which may persist throughout life, as for most congenital thyroid disorders, or be transient, resolving in the first few weeks of life, as in autoimmune hyperthyroidism or hypothyroidism and some cases of congenital hypothyroidism (CH) with the thyroid gland in situ. Primary CH is diagnosed by neonatal screening, which has been implemented for 40 years in developed countries and should be introduced worldwide, as early treatment prevents irreversible neurodevelopmental delay. Central CH is a rarer entity occurring mostly in association with multiple pituitary hormone deficiencies. Other rare disorders impair the action of thyroid hormones. Neonatal Graves' disease (GD) results from the passage of thyrotropin receptor antibodies (TRAbs) across the placenta, from mother to fetus. It may affect the fetuses and neonates of mothers with a history of current or past GD, but hyperthyroidism develops only in those with high levels of stimulatory TRAb activity. The presence of antibodies predominantly blocking thyroid-stimulating hormone receptors may result in transient hypothyroidism, possibly followed by neonatal hyperthyroidism, depending on the balance between the antibodies present. Antithyroid drugs taken by the mother cross the placenta, treating potential fetal hyperthyroidism, but they may also cause transient fetal and neonatal hypothyroidism. Early diagnosis and treatment are key to optimizing the child's prognosis. This review focuses on the diagnosis and management of these patients during the fetal and neonatal periods. It includes the description of a case of fetal and neonatal autoimmune hyperthyroidism.

Follow-Up of Thyroid Function in Children With Neonatal Hyperthyroidism

INTRODUCTION

Neonatal hyperthyroidism mainly occurring in the children born to mothers with Graves' disease (GD). The influence of maternal GD on the newborn's thyroid function includes not only hyperthyroidism, but also various forms of hypothyroidism. Maternally transferred thyrotropin receptor antibodies (TRAb), the antithyroid drug (ATD) administration during pregnancy and previous definitive treatment of GD (radioactive iodine therapy or thyroidectomy) in the mother impact the function of the fetal/neonatal thyroid. Some newborns born to mothers with GD may present central hypothyroidism (CeH) due to impaired regulation of the fetal hypothalamic-pituitary-thyroid axis. The aim of this study was to evaluate different types of thyroid dysfunction in babies with neonatal hyperthyroidism.

MATERIALS AND METHODS

Medical records of 14 infants with neonatal hyperthyroidism (13 born to mothers with GD, and one born to mother with Hashimoto thyroiditis) were analyzed.

RESULTS

Transient hyperthyroidism was the main thyroid dysfunction in our study group. Overt hyperthyroidism with highly increased TRAb levels (mean 13.0 ± 7.0 IU/L) was diagnosed in 6 (43%) neonates. Another 6 (43%) babies presented hyperthyroidism with slightly increased fT4 and/or fT3 levels and TSH levels in the lower limit of the normal range coinciding with positive TRAb levels (mean 3.8 ± 1.6 IU/L). Normal thyroid hormone levels with TSH levels below the lower limit of the range were observed in 2 (14%) neonates. Four babies in the study group (28.5%) required further levothyroxine (L-T4) supplementation due to CeH or, in one case, due to primary hypothyroidism.

CONCLUSION

Our study highlights the need for prolonged monitoring of thyroid function in children born to mothers with GD. Diagnosis of CeH could be delayed due to its masking by transient hyperthyroidism. Prolonged thyroid-stimulating hormone suppression after TRAb elimination should be considered as a signal announcing CeH.

A Case of Neonatal Thyrotoxicosis with Cardiac Insufficiency

Neonatal thyrotoxicosis is rare and most of the cases are secondary to maternal Graves’ disease. It is usually transient, but can be associated with significant morbidity and mortality if not recognized promptly and treated adequately. Neonates born to mothers treated with antithyroid drugs or those who receive maternal thyroid blocking antibodies may exhibit normal thyroid function or even hypothyroidism at birth. Since there may not be any obvious symptoms of hyperthyroidism at birth, it may be overlooked. Therefore, such neonates should be evaluated properly and monitored regularly to prevent serious complications of hyperthyroidism. We report a case of a 21-day-old male infant who developed thyrotoxicosis with dyspnea, irritability, tachycardia, and cardiac insufficiency. He was born to a mother who was treated for Graves’ disease with antithyroid drugs during pregnancy. We have also discussed the importance of careful examination and monitoring to prevent the development of clinical hyperthyroidism.

The Clinical Value and Variation of Antithyroid Antibodies during Pregnancy

Antithyroid antibodies, which include thyroid-stimulating hormone receptor antibodies (TRAbs), thyroid peroxidase antibodies (TPOAbs), and thyroid globulin antibodies (TgAbs), are widely known for their tight association with thyroid autoimmune diseases. The variation in all three kinds of antibodies also showed different trends during and after pregnancy (Weetman, 2010). This article reviewed the the physiological changes, while focusing on the variation of thyroid antibodies concentration in women during and after pregnancy, and adverse consequences related to their elevation. Since abnormal elevations of these antithyroid antibodies may lead to adverse outcomes in both mothers and fetuses, special attention must be paid to the titer of the antibodies during pregnancy. The molecular mechanisms of the variations in those antibodies have yet to be explained. The frequency and timing of thyroid antibody measurement, as well as different reference levels, also remain to be elucidated.

Reducing unnecessary neonatal testing in infants of mothers with thyroid disease

AIM

To examine the numbers of asymptomatic infants <8 weeks who had appropriate thyroid function tests (TFTs) in addition to the newborn screening test, because of maternal thyroid disease, before and after the implementation of an updated institutional guideline and staff education.

METHODS

A medical record audit of infants <8 weeks born at a metropolitan teaching hospital, who had TFTs between 1 July 2017 and 31 October 2017 was performed as part of a quality improvement project. Records were reviewed to determine the indication for testing and whether this complied with the current 2011 institutional guideline. A multidisciplinary staff education package was developed to coincide with the publication of an updated guideline in August 2018. Staff education and resources were provided throughout July 2018. A post-intervention audit was repeated between 1 August 2018 and 1 December 2018, assessing compliance with the 2018 guideline.

RESULTS

In the baseline period, 40 of 457 infants born had TFTs performed, of which 26 of 40 (65%) were for maternal thyroid disease. Of these 10 of 26 (38%) met the 2011 criteria for testing; 1 of 26 (4%) met the updated 2018 criteria. In the post-intervention period, 14 of 412 infants born had TFTs of which 5 of 14 (36%) were tested due to maternal thyroid disease and all were compliant with the new guideline.

CONCLUSIONS

Baseline audit revealed unnecessary neonatal thyroid function testing of healthy babies. Implementation of an updated guideline and a brief, targeted education package successfully increased awareness of the updated recommendations, reduced unnecessary testing and led to improved practice.

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.

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.

Maternal Graves’ disease and fetal tetralogy of Fallot: a case series

Background

Congenital heart defects have been reported with the use of antithyroid medication with ventricular septal defects (VSD) being the most common. As per the current practice guidelines maternal Graves’ disease (GD) is not an indication for fetal echocardiogram.

Case presentation

We described three neonates with tetralogy of Fallot (TOF) born to mothers with GD. Only one of the mothers was on antithyroid medication. Two of these neonates were diagnosed postnatally when they failed the pulse oximeter congenital cardiac screening and diagnosis was established by postnatal echocardiogram. Two of the mothers had radioactive iodine ablation and were on levothyroxine during pregnancy. The dose of levothyroxine was increased during pregnancy. There was no other complication during pregnancy. The third mother had hyperthyroidism and developed a thyroid storm during pregnancy requiring inpatient admission and treatment with propylthiouracil (PTU), metoprolol and methimazole. All babies had normal thyroid function test postnatally and eventually had successful repair of TOF defect.

Conclusion

We report the largest known case series of children with TOF born to mothers with GD. Apart from the isolated reports of fetal TOF in mothers with GD, there is no clear association between fetal TOF and maternal GD and antithyroid medication. Based on the review of the literature and our case series, there may be an increased incidence of congenital heart defects in maternal GD irrespective of antithyroid medication use. This case series may add to the current knowledge base and support routine fetal echocardiogram screening for all mothers with GD.

The Role of Thyroid Diseases and their Medications in Cardiovascular Disorders: A Review of the Literature

The association between thyroid disease and cardiovascular manifestations is significant and undeniable. Previous studies have explained several aspects of the effects of thyroid hormone on the heart and cardiovascular system. Accordingly, both hyper and hypothyroidism can cause important alterations in cardiac rhythm, output and contractility as well as vascular resistance and blood pressure. Since treating the thyroid abnormality, especially in its initial stages, could lead to a significant improvement in most of its resultant cardiovascular disturbances, early suspicion and recognition of thyroid dysfunction, is necessary in patients with cardiovascular manifestations. In this in-depth review, we discuss the physiological roles as well as the effects of abnormal levels of thyroid hormones on the cardiovascular system. We also review the effects of the medications used for the treatment of hyper and hypothyroidism on cardiac function. In the end, we discuss the association between thyroid function and amiodarone, an effective and frequently-used antiarrhythmic drug, because of its well-known effects on the thyroid.

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.

Macular Rash, Thrombocytopenia, and Hyperbilirubinemia in a Preterm Infant

Neonatal hyperthyroidism is usually caused by the passage of maternal thyroid receptor antibodies. This relatively rare condition has various manifestations including cholestasis, prematurity, and cardiomegaly. We present a case of a preterm infant with neonatal Graves' disease who presented with cholestasis, cardiomegaly, and a macularpapular rash that was thought to be suspicious for congenital infection. This case has been reported to illustrate lessons learnt for early identification of a neonate with Graves' disease in order to expedite treatment.

Management of fetal goiters: 6-year retrospective observational study in three prenatal diagnosis and treatment centers of the Pays De Loire Perinatal Network

Introduction: The incidence of fetal goiters is reported to be around 1 per 40,000 births. The risk of complications is first of all obstetric, directly related to goiter size, but it may also affect longer term fetal and child development, depending on whether the goiter is due to hypo- or hyperthyroidism. Management is multidisciplinary, but not yet consensual and not always optimal by either endocrinologists or obstetricians.Objectives: The principal objective of this retrospective study was to analyze the data that enabled the physicians to assess whether the goiter was hypo- or hyperthyroid and then to analyze the obstetric practices used in the Pays de Loire network to describe in detail the tools used to diagnose and characterize the goiters and the management chosen in these cases. The secondary objectives are to assess, in our small cohort, the effectiveness of the in utero treatments provided, based on the examination of the children at birth and their outcome at 6 months of life, and to suggest a strategy for monitoring these women at risk that takes current guidelines into consideration.Materials and methods: This multicenter retrospective study covers a 6-year period and focused on the prenatal diagnosis centers (CPDPN) of the Pays de Loire perinatal network: in Nantes, Angers, and Le Mans. The network is responsible for around 42,000 births a year, and the study included 17 women, for a prevalence of 1 per 15,000 births.Results: Ten of the 17 fetuses had a hypothyroid goiter, 4 a hyperthyroid goiter, and 3 normal thyroid findings on fetal blood sample (FBS). For four women, these goiters were secondary to fetal dyshormonogenesis, for 9 more to Graves disease with TSH receptor antibodies (TRAb), and for four women to thyrotoxicosis at the start of pregnancy, managed by synthetic antithyroid drugs. Two newborns had severe complications associated with maternal transmission of Graves disease (TRAb positive at birth): one with exophthalmos and one with neonatal tachycardia. The other 14 had normal psychomotor development at 6 months, based on a clinical examination by a pediatric endocrinologist; only one child was lost to follow-up.Conclusion: Together, ultrasound and multidisciplinary expertise (of an endocrinologist and an obstetrician experienced with this disease) remain the best means for avoiding, or otherwise for accurately characterizing fetal goiter. An ultrasound diagnostic score, of the type proposed by Luton et al. in 2009, may make it possible to homogenize practices and thus to defer or delay the - currently too common - performance of invasive FBS procedures, which must remain rare in this management to limit comorbidities. A threshold TRAb value (>5 IU/l) makes it possible to define this group of women as at risk of fetal and neonatal hyperthyroidism and thus requiring close monitoring. The value of prenatal intra-amniotic thyroxine treatment for hypothyroid goiters (including dyshormonogenesis) remains to be demonstrated.

Incidence of Neonatal Hyperthyroidism Among Newborns of Graves' Disease Patients Treated with Radioiodine Therapy

BACKGROUND

The serum thyrotropin receptor antibody (TRAb) titers of Graves' disease (GD) patients are known to increase after radioiodine (RAI) therapy, and they can remain high for years. The incidence of neonatal hyperthyroidism (NH) among newborns of mothers with GD who conceived after RAI therapy has not been previously reported. The aims of this study were to investigate the incidence of NH among newborns of mothers who conceived within two years after RAI therapy, and to identify predictors of NH.

METHODS

GD patients (n = 145) who conceived within two years after RAI therapy were retrospectively reviewed, and information regarding their newborns was collected.

RESULTS

Of the 145 pregnant women, 54 (37%) were treated with antithyroid drugs or potassium iodide for maternal hyperthyroidism during the first trimester. There were eight newborns with NH, resulting in an incidence of 5.5%. Seven of the eight mothers whose newborns had NH were treated with antithyroid drugs or potassium iodide during their pregnancy. The incidence of NH among the newborns of mothers who conceived within 6-12 months after RAI therapy was 8.8%, within 12-18 months was 5.5%, and within 18-24 months was 3.6%. Multivariate analysis revealed that the TRAb values in the third trimester were the only risk factor for NH. The cutoff TRAb value in the third trimester for predicting NH was 9.7 IU/L (reference value <2.0 IU/L).

CONCLUSIONS

The incidence of NH among newborns of mothers who conceived within two years after RAI therapy was 5.5%. The fetuses of pregnant GD patients whose TRAb value is high in the third trimester should be carefully followed by an obstetrician during pregnancy, and the newborns should be carefully followed by a pediatrician after birth.

Inconsistencies in the management of neonates born to mothers with "thyroid diseases"

Although thyroid medications are frequently prescribed during pregnancy, paediatricians treating the respective neonates often have no information about the underlying maternal thyroid disease, and inconsistencies in postnatal diagnostics may result. We analysed a cohort of 1819 mothers admitted for delivery in 1 year to one hospital. We analysed the pre- and postpartum diagnostics in the mothers, the postnatal diagnostics in the neonates and their postnatal auxological development. Two hundred thirteen mothers (11.7%) had "thyroid disease"; 37 (2.0%) had Hashimoto thyroiditis, seven (0.4%) Graves' disease and 169 (9.3%) "thyroid disease of other origins". One hundred eighty-eight out of 213 (88%, 10.3% of the entire cohort) took levothyroxine. Pre- and postpartum diagnostics of the mothers and postnatal diagnostics of the neonates revealed striking inconsistencies. For example, 39 % of the gynaecologists routinely determined TSH, while only 59% carried out a dosage adjustment for known hypothyroidism. Second specialists were consulted in 86%. Unnecessary postpartum diagnostics were initiated in 19/213 neonates (9%). TRAb was analysed, however, in only one neonate born from the mothers with Graves' disease-a condition in which further diagnostic efforts are mandatory.Conclusion: Although many pregnant women have thyroid dysfunction, we observed a lack of uniformity in the diagnostic approach of the women and their neonates. What is Known: • Disturbed maternal thyroid function in pregnancy often has an adverse impact on both the mother and the foetus. • Although detailed guidelines for managing impaired maternal thyroid function during pregnancy have been published, their application in clinical practice varies widely. What is New: • Recommendations for managing the newborn of a mother presenting with thyroid disease of unknown entity are remarkably inconsistent. • This leads to a possible over-diagnosis in general and a potentially life-threatening failure to note neonatal hyperthyroidism requiring rapid treatment.

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.

[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.

Graves' disease and pregnancy

This section deals with the specificities of managing Graves' disease during pregnancy. Graves' disease incurs risks of fetal, neonatal and maternal complications that are rare but may be severe: fetal hyper- or hypothyroidism, usually first showing as fetal goiter, neonatal dysthyroidism, premature birth and pre-eclampsia. Treatment during pregnancy is based on antithyroid drugs alone, without association to levothyroxine. An history of Graves' disease, whether treated radically or not, with persistent maternal anti-TSH-receptor antibodies must be well identified. Fetal monitoring should be initiated in a multidisciplinary framework that should be continued throughout pregnancy. Neonatal monitoring is also crucial if the mother still shows anti-TSH-receptor antibodies at end of pregnancy or underwent antithyroid treatment. The risk of recurrence of hyperthyroidism in the weeks following delivery requires maternal monitoring. The long-term neuropsychological progression of children of mothers with Graves' disease is poorly known.

Diagnosis and management of hyperthyroidism from prenatal life to adolescence

Hyperthyroidism in children is a rare heterogeneous syndrome characterized by excessive thyroid hormone production. Its manifestations differ according to disease severity. For all forms of hyperthyroidism, treatment aims to restore a euthyroid state, enabling the child to demonstrate appropriate metabolism, growth, and neurocognitive development. Graves' disease is the most frequent cause of hyperthyroidism in children. Treatment modalities include antithyroid drugs, with the advantage that prolonged treatment for several years can be followed by freedom from medical intervention in about 40-50% of cases. It may also be treated with radioactive iodine or, less frequently, thyroidectomy, these more radical treatments both necessitating subsequent lifelong levothyroxine treatment. Particular care is required in the management of pregnant women with Graves' disease. Fetal and neonatal forms of hyperthyroidism are transient and rare, but nevertheless serious. Here, we provide an overview of the best approach to hyperthyroidism diagnosis and management, from fetal development to adolescence.

Prediction of Neonatal Hyperthyroidism

OBJECTIVES

To assess whether it is possible to identify the neonatal predictors of neonatal hyperthyroidism at the presymptomatic stage of the disease.

STUDY DESIGN

This retrospective multicenter study in 10 maternity units was based on the medical records of all patients monitored for a pregnancy between January 1, 2007, and January 1, 2014. Among 280 000 births, 2288 medical records of women with thyroid dysfunction were selected and screened. Of these, 415 women had Graves disease and were positive for thyrotropin receptor antibody during pregnancy, and were included.

RESULTS

A thyroid-stimulating hormone (TSH) level of less than 0.90 mIU/L between days 3 and 7 of life predicted neonatal hyperthyroidism with a sensitivity 78% (95% CI, 74%-82%) and a and specificity of 99% (95% CI, 98%-100%), a positive predictive value of 90% (95% CI, 87%-93%), a negative predictive value of 98% (95% CI, 97%-99%), and an area under the receiver operating characteristic curve of 0.99 (95% CI, 0.97-1.0). A thyrotropin receptor antibody (TRAb) elimination time was calculated using the equation: 7.28 + 2.88 × log() + 11.62 log(TRAb²).

CONCLUSIONS

All newborns with a TSH level of less than 0.90 mIU/L should be examined by a pediatrician. Using TSH, it is possible to screen for neonatal hypothyroidism and for neonatal hyperthyroidism with a TSH cutoff of 0.90 mIU/L, and this shows the relevance of our study in terms of public health.

False-positive TSH receptor antibody-a pitfall of third-generation TSH receptor antibody measurements in neonates

Maternal Graves' disease (GD) during pregnancy may influence thyroid function in fetuses. Neonates born to mothers with high serum TSH receptor antibody (TRAb) levels have been reported to develop 'neonatal GD'. Therefore, evaluations of serum thyroid hormone and TRAb levels in neonates upon birth are crucial for a prompt diagnosis. At delivery, we measured TRAb with third-generation TRAb test using an M22 human monoclonal antibody in neonates by collecting umbilical cord blood in a blood collection tube with lithium-heparin, which provides a whole blood/plasma sample. In recent years, we have encountered positive TRAb levels (more than 2.0 IU/L) in nineteen neonates born to mothers with GD whose thyroid hormone levels were almost within the reference range and serum TRAb levels were less than 10 IU/L. All the neonates with positive TRAb levels did not exhibit thyrotoxicosis. However, when we measured TRAb levels with serum sample in six out of the nineteen cases, their serum TRAb levels were all negative, suggesting a discrepancy of TRAb levels between in lithium-heparin plasma from umbilical cord blood and serum. Moreover, this discrepancy was observed in neonates born to euthyroid mothers, adult active GD patients and healthy volunteers. Since lithium-heparin plasma from umbilical cord blood is widely used in laboratory tests at delivery, we may encounter 'false-positive' TRAb, which may, in turn, lead to a misdiagnosis of neonatal GD. This is a pitfall of third-generation TRAb measurements in neonates, particularly at delivery, and needs to be considered by obstetricians and neonatologists.

Central congenital hypothyroidism caused by maternal thyrotoxicosis

Central congenital hypothyroidism (CCH) is a rare and underdiagnosed disease that sometimes is caused by maternal Graves' disease. We report a case of CCH caused by undiagnosed, initially antibody-negative maternal thyrotoxicosis with possible disruption of fetal hypothalamic-pituitary-thyroid axis maturation. In CCH, maternal thyroid disease should be considered.

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.

Neonatal Thyrotoxicosis

Neonatal thyrotoxicosis (hyperthyroidism) is less prevalent than congenital hypothyroidism; however, it can lead to significant morbidity and mortality if not promptly recognized and adequately treated. Most cases are transient, secondary to maternal autoimmune hyperthyroidism (Graves disease [GD]). This article summarizes recommendations for screening and management of hyperthyroidism in both the fetal and neonatal periods, with a focus on neonatal thyrotoxicosis secondary to maternal GD. Early monitoring and treatment are crucial for optimizing short-term and long-term patient outcomes.

Maternal Thyrotropin Receptor Antibody Concentration and the Risk of Fetal and Neonatal Thyrotoxicosis: A Systematic Review

BACKGROUND

In pregnant women with Graves' disease, maternal thyrotropin receptor antibodies (TRAb) can cross the placenta and induce fetal or neonatal thyrotoxicosis. Symptoms of fetal thyrotoxicosis are tachycardia, intrauterine growth restriction, and intra-uterine death. Recommendations on an upper limit of TRAb concentrations below which intensive fetal monitoring can be safely omitted vary between different guidelines. The objective of this study was to define an evidence-based cutoff level for maternal TRAb necessitating additional fetal monitoring during pregnancy.

METHODS

A literature search was performed to identify studies on pregnant women with Graves' disease and fetal and/or neonatal thyrotoxicosis. Only studies that reported TRAb were included.

RESULTS

From a total of 229 identified titles, 20 articles could be included in the analysis. A total of 53 cases of fetal and/or neonatal thyrotoxicosis were described. The lowest level of maternal TRAb leading to neonatal thyrotoxicosis was 4.4 U/L, which corresponds to 3.7 times the upper limit of normal. The level of evidence for this threshold is moderate to low.

CONCLUSION

In women with Graves' disease, intensive fetal monitoring is recommended when maternal TRAb concentrations are >3.7 times the upper limit of normal. This cutoff level should be interpreted with caution, since evidence is limited.

[Neonatal hyperthyroidism: A sometimes challenging diagnosis]

Graves disease complicates two pregnancies out of 1000 and when it is known before pregnancy, it warrants careful monitoring of the fetus and the newborn. We report on a case of neonatal hyperthyroidism, which revealed a previously unknown maternal thyroid disease. In this situation, neonatal signs can be misinterpreted, delaying the diagnosis. Neonatal hyperthyroidism is, however, a therapeutic emergency because of the risk of cardiac and neurological complications. The neonatologist must identify thyroid disease in the absence of a maternal history in order to promptly start therapy.

Study of the Factors Leading to Fetal and Neonatal Dysthyroidism in Children of Patients With Graves Disease

CONTEXT

Neonatal hyperthyroidism was first described in 1912 and in 1964 was shown to be linked to transplacental passage of maternal antibodies. Few multicenter studies have described the perinatal factors leading to fetal and neonatal dysthyroidism.

OBJECTIVE

To show how fetal dysthyroidism (FD) and neonatal dysthyroidism (ND) can be predicted from perinatal variables, in particular, the levels of anti-thyrotropin receptor antibodies (TRAbs) circulating in the mother and child.

DESIGN AND PATIENTS

This was a retrospective multicenter study of data from the medical records of all patients monitored for pregnancy from 2007 to 2014.

SETTING

Among 280,000 births, the medical records of 2288 women with thyroid dysfunction were selected and screened, and 417 women with Graves disease and positive for TRAbs during pregnancy were included.

RESULTS

Using the maternal TRAb levels, the cutoff value of 2.5 IU/L best predicted for FD, with a sensitivity of 100% and specificity of 64%. Using the newborn TRAb levels, the cutoff value of 6.8 IU/L best predicted for ND, with a sensitivity of 100% and a specificity of 94%. In our study, 65% of women with a history of Graves disease did not receive antithyroid drugs during pregnancy but still had infants at risk of ND.

CONCLUSIONS

In pregnant women with TRAb levels ≥2.5 IU/L, fetal ultrasound monitoring is essential until delivery. All newborns with TRAb levels ≥6.8 IU/L should be examined by a pediatrician with special attention for thyroid dysfunction and treated, if necessary.

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.

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.

Thyroid-Stimulating Hormone Receptor Antibodies in Pregnancy: Clinical Relevance

Graves' disease is the most common cause of thyrotoxicosis in women of childbearing age. Approximately 1% of pregnant women been treated before, or are being treated during pregnancy for Graves' hyperthyroidism. In pregnancy, as in not pregnant state, thyroid-stimulating hormone (TSH) receptor (TSHR) antibodies (TRAbs) are the pathogenetic hallmark of Graves' disease. TRAbs are heterogeneous for molecular and functional properties and are subdivided into activating (TSAbs), blocking (TBAbs), or neutral (N-TRAbs) depending on their effect on TSHR. The typical clinical features of Graves' disease (goiter, hyperthyroidism, ophthalmopathy, dermopathy) occur when TSAbs predominate. Graves' disease shows some peculiarities in pregnancy. The TRAbs disturb the maternal as well as the fetal thyroid function given their ability to cross the placental barrier. The pregnancy-related immunosuppression reduces the levels of TRAbs in most cases although they persist in women with active disease as well as in women who received definitive therapy (radioiodine or surgery) before pregnancy. Changes of functional properties from stimulating to blocking the TSHR could occur during gestation. Drug therapy is the treatment of choice for hyperthyroidism during gestation. Antithyroid drugs also cross the placenta and therefore decrease both the maternal and the fetal thyroid hormone production. The management of Graves' disease in pregnancy should be aimed at maintaining euthyroidism in the mother as well as in the fetus. Maternal and fetal thyroid dysfunction (hyperthyroidism as well as hypothyroidism) are in fact associated with several morbidities. Monitoring of the maternal thyroid function, TRAbs measurement, and fetal surveillance are the mainstay for the management of Graves' disease in pregnancy. This review summarizes the biochemical, immunological, and therapeutic aspects of Graves' disease in pregnancy focusing on the role of the TRAbs in maternal and fetal function.

ENDOCRINOLOGY IN PREGNANCY: Pregnancy and the incidence, diagnosing and therapy of Graves' disease

Thyroid hormones are essential developmental factors, and Graves' disease (GD) may severely complicate a pregnancy. This review describes how pregnancy changes the risk of developing GD, how early pregnancy by several mechanisms leads to considerable changes in the results of the thyroid function tests used to diagnose hyperthyroidism, and how these changes may complicate the diagnosing of GD. Standard therapy of GD in pregnancy is anti-thyroid drugs. However, new studies have shown considerable risk of birth defects if these drugs are used in specific weeks of early pregnancy, and this should be taken into consideration when planning therapy and control of women who may in the future become pregnant. Early pregnancy is a period of major focus in GD, where pregnancy should be diagnosed as soon as possible, and where important and instant change in therapy may be warranted. Such change may be an immediate stop of anti-thyroid drug therapy in patients with a low risk of rapid relapse of hyperthyroidism, or it may be an immediate shift from methimazole/carbimazole (with risk of severe birth defects) to propylthiouracil (with less risk), or maybe to other types of therapy where no risk of birth defects have been observed. In the second half of pregnancy, an important concern is that not only the mother with GD but also her foetus should have normal thyroid function.

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.

Interpreting Minor Variations in Thyroid Function or Echostructure: Treating Patients, Not Numbers or Images

Overt thyroid dysfunction is documented by serum thyrotropin or T4 concentrations are often ordered for nonspecific complaints and will by definition fall outside of the 95% reference range 5% of the time. In addition, most laboratories quote adult ranges, which are not necessarily applicable to young children, and regression toward the mean is common, justifying that the test be repeated before embarking on treatment. On the other hand, neck ultrasounds are frequently performed for diffuse goiter or non-thyroid conditions. Yet, an ultrasound is not required to make a diagnosis of Hashimoto thyroiditis and small cysts and nodules discovered incidentally often lead to unjustified concerns about neoplasia.

Predictive value of maternal second-generation thyroid-binding inhibitory immunoglobulin assay for neonatal autoimmune hyperthyroidism

CONTEXT

Hyperthyroidism occurs in 1% of neonates born to mothers with active or past Graves' disease (GD). Current guidelines for the management of GD during pregnancy were based on studies conducted with first-generation thyroid-binding inhibitory immunoglobulin (TBII) assays.

OBJECTIVE

This retrospective study was conducted in order to specify the second-generation TBII threshold predictive of fetal and neonatal hyperthyroidism, and to identify other factors that may be helpful in predicting neonatal hyperthyroidism.

METHODS

We included 47 neonates born in the Lyon area to 42 mothers harboring measurable levels of TBII during pregnancy. TBII measurements were carried out in all mothers; bioassays were carried out in 20 cases.

RESULTS

Nine neonates were born with hyperthyroidism, including five with severe hyperthyroidism requiring treatment. Three neonates were born with hypothyroidism. All hyperthyroid neonates were born to mothers with TBII levels >5 IU/l in the second trimester (sensitivity, 100% and specificity, 43%). No mother with TSH receptor-stimulating antibodies (TSAb measured by bioassay) below 400% gave birth to a hyperthyroid neonate. Among mothers of hyperthyroid neonates, who required antithyroid drugs during pregnancy, none could stop treatment before delivery. Analysis of TBII evolution showed six unexpected cases of increasing TBII values during pregnancy.

CONCLUSION

Maternal TBII value over 5 IU/l indicates a risk of neonatal hyperthyroidism. Among these mothers, a TSAb measurement contributes to identify more specifically those who require a close fetal thyroid ultrasound follow-up. These results should be confirmed in a larger series.