Anti TSH-receptor antibodies in pregnant patients with autoimmune thyroid disorder

Utility of Antibodies in the Diagnoses of Thyroid Diseases: A Review Article

Thyroid problems are among the most widespread endocrine illnesses, affecting individuals in India and the global population. A thyroid function test is used to diagnose, screen, and monitor patients. Hyperthyroidism is a clinical condition due to excessive circulation of thyroid hormone; in contrast, hypothyroidism is due to a deficiency of thyroid hormone. Graves' disease (GD) is a form of hyperthyroidism due to thyroid-stimulating hormone receptor autoantibodies (TRAb), and anti-thyroid peroxidase antibodies (anti-TPO antibodies). The most common reason for hypothyroidism is Hashimoto's thyroiditis (HT), in which patients have thyroid receptor antibodies (TRAb), antibodies to thyroid peroxidase (TPO), and thyroglobulin antibodies. Many essential genes, including the thyroid-specific genes thyroglobulin (TSGT), TSH-receptor gene, human leukocyte antigen (HLA) genes, cytotoxic T lymphocyte-associated antigen (CTLA) genes, thyroglobulin gene, vitamin D receptor gene, and many immune-regulatory genes were associated with autoimmune thyroid diseases' (AITDs') etiology. This review paper aims to determine if antibodies are beneficial in detecting autoimmune thyroid disease or not. We have also discussed the etiology of autoimmune thyroid illness, serum antibodies in autoimmune thyroid disease, pathophysiology, and TSH receptor features.

Role of Maternal Thyroid-Stimulating Immunoglobulin in Graves' Disease for Predicting Perinatal Thyroid Dysfunction

Objective  To assess maternal thyroid-stimulating immunoglobulin (TSI) as a predictor of neonatal thyroid hyperthyroidism in pregnancies complicated by Graves' disease. Methods  This is a 10-year retrospective study of patients with a history of Graves' disease and elevated TSI activity level defined as 1.3 times the normal. All subjects underwent cordocentesis for ultrasound findings of suspected fetal thyrotoxicosis (fetal tachycardia, oligohydramnios, hydrops, and thyromegaly). Neonatal diagnosis was made based on neonatal thyroid function testing or symptoms. Results  Fourteen patients were included in the study, seven with active Graves' disease requiring antithyroid drug ("ATD group") and seven with iatrogenic hypothyroidism on levothyroxine ("levothyroxine group"). Four cases (57%) of neonatal thyrotoxicosis were diagnosed in the levothyroxine group compared with two cases (28%) in the ATD group. The lowest maternal TSI level at which a neonate did not develop hyperthyroidism was 2.6 for the levothyroxine group and 2.5 for the ATD group. The odds ratio of a neonate from the levothyroxine group developing hyperthyroidism compared with one from the ATD group is 3.3 (95% confidence interval: 0.4-30.7). Conclusion  For patients with Graves' disease, those with iatrogenic hypothyroidism and TSI > 2.5 times the basal level are at the highest risk for neonatal thyrotoxicosis.

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.

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.

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.

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.

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.

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.

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

OBJECTIVE

Hyperthyroidism in neonates born to mothers with Graves' disease (GD) can be associated with significant morbidity and mortality, but is still overlooked by clinicians. Management of neonatal hyperthyroidism would be improved by a better understanding of the predictive factors involved. The aim of this study was to evaluate the course of thyroid function and clinical outcomes during the first postnatal month in babies born to mothers with GD.

DESIGN

Prospective observational study.

METHODS

Sixty-eight neonates born to mothers with GD were managed from birth and divided into three groups based on thyrotropin receptor antibody (TRAb) and anti-thyroid drug (ATD) status in the mother: TRAb(-ve)/ATD(-ve), n=27; TRAb(-ve)/ATD(+) (ve), n=8; and TRAb(+ve)/ATD(+ve), n=33. The main outcome measures were clinical examination, thyroid function tests (TSH, free thyroxine (FT4), free triiodothyronine, and TRAb), echocardiography, thyroid ultrasonography, and bone maturation assessment.

RESULTS

None of the infants born to TRAb(-ve) mothers with GD developed neonatal hyperthyroidism. Of the 33 TRAb(+ve)/ATD(+ve) neonates, 24 (72.7%) had positive TRAb on cord blood assays, and seven of these developed neonatal hyperthyroidism. FT4 elevation between days 3 and 7 but not at birth was predictive of the development of hyperthyroidism.

CONCLUSIONS

TRAb status should be checked in the third trimester in mothers with GD and on cord blood in their neonates; if positive, it indicates a high risk of neonatal hyperthyroidism. FT4 measurement at birth should be repeated between days 3 and 5 (and by day 7 at the latest); rapid FT4 elevation during the first postnatal week is predictive of hyperthyroidism and warrants ATD therapy.

Follow-up of newborns of mothers with Graves' disease

BACKGROUND

Overt neonatal Graves' disease is rare, but may be severe, even life threatening, with deleterious effects on neural development. The main objective of this study was to describe the course of thyrotropin (TSH) and free thyroxin (fT4) levels, as well as postnatal weight gain in relation to fT4 levels, in neonates born to women with Graves' disease without overt neonatal thyrotoxicosis. Such information is important to deduce the optimal schedule for evaluation.

METHODS

We conducted a retrospective chart review of neonates born to mothers with Graves' disease between January 2007 and December 2012. The records were reviewed for sex, gestational age, birth weight, maternal treatment during pregnancy, and maternal thyroid stimulating immunoglobulin (TSI) level. For each visit in the clinic, the data included growth parameters, presence of symptoms suspected for hyperthyroidism, blood test results (levels of TSH, fT4, and TSI), and treatment.

RESULTS

Ninety-six neonates were included in the study (49 males), with a total of 320 measurements of thyroid function tests (TSH and fT4). Four neonates (4%) had overt neonatal Graves' disease; one of them along with nine others were born preterm. In 77 (92.9%) of the remaining 83 neonates (the subclinical group), fT4 levels were above the 95th percentile on day 5. All had normal fT4 on day 15. A negative association was found between fT4 and weight gain during the first two weeks.

CONCLUSIONS

In this cohort, most neonates born to mothers with Graves' disease had a subclinical course with abnormal fT4 levels that peaked at day 5. After day 14, all measurements of fT4 returned to the normal range, although measurements of TSH remained suppressed for up to three months. Elevated fT4 was associated with poor weight gain.

Clinical review: Clinical utility of TSH receptor antibodies

CONTEXT

TSH receptor antibodies (TRAb) cause Graves' disease (GD) hyperthyroidism. Widely available TRAb measurement methods have been significantly improved recently. However, the role of TRAb measurement in the differential diagnosis of hyperthyroidism, the prediction of remission of GD hyperthyroidism, the prediction of fetal/neonatal thyrotoxicosis, and the clinical assessment of Graves' ophthalmopathy (GO) are controversial.

EVIDENCE ACQUISITION

We reviewed and analyzed the literature reporting primary data on the clinical use of TRAb. We focused our analyses on clinical studies analyzing third-generation TRAb assays.

EVIDENCE SYNTHESIS

The performance of TRAb in the differential diagnosis of overt hyperthyroidism is excellent, with sensitivity and specificity in the upper 90%. TRAb can accurately predict short-term relapses of hyperthyroidism after a course of antithyroid drugs but are less effective in predicting long-term relapses or remissions. Pregnancies in women with GD with negative TRAb are highly unlikely to result in fetal hyperthyroidism, whereas high titers of TRAb in pregnancy require careful fetal monitoring. GD patients with GO frequently have high TRAb levels. However, there are insufficient data to use the test to predict the clinical course of GO and response to treatment.

CONCLUSIONS

Third-generation TRAb assays are suitable in the differential diagnosis of hyperthyroidism. In GD, TRAb should be tested before deciding whether methimazole can be stopped. TRAb should be used in pregnant women with GD to assess the risk of fetal thyrotoxicosis. The use of TRAb in GO requires further studies.

The role of thyrotrophin receptor antibody assays in graves' disease

Thyrotrophin receptor antibodies (TRAb) exist as stimulating or blocking antibodies in the serum (neutral TRAb have been identified recently). The clinical features of GD occur when stimulating TRAb predominate. But the relationship of TRAb to clinical phenotype and outcome is not clear when current assay methods are used. Therefore no consensus exists about its utility in diagnosing and predicting outcome in GD. The most commonly used TRAb assays, measure thyroid binding inhibiting immunoglobulins (TBII or “receptor assays”) and don't differentiate between stimulating and blocking antibodies. However, the more expensive, technically demanding and less freely available “biological assays” differentiate between them by their ability to stimulate cyclic AMP or failure to do so. Failure to differentiate between TRAb types and its heterogeneous molecular and functional properties has limited TBII use to GD diagnosis and differentiating from other forms of thyrotoxicosis. The current 2nd-3rd generation receptor assays are highly sensitive and specific when used for this purpose. TRAb assays should also be done in appropriate pregnant women. Current data do not support its use in outcome prediction as there is a significant variability of assay methodology, population characteristics and study design in published data, resulting in a lack of consensus.

Persistent high TRAb values during pregnancy predict increased risk of neonatal hyperthyroidism following radioiodine therapy for refractory hyperthyroidism

Serum levels of TSH receptor antibody (TRAb) often increase after radioiodine treatment for Graves' disease, and high-serum levels of maternal TRAb in late pregnancy indicate a risk of neonatal hyperthyroidism. The aim of this retrospective study is to investigate the characteristics of Graves' women who had a history of radioiodine treatment for intractable Graves' disease, and whose neonates suffered from hyperthyroidism. The subjects of this study were 45 patients with Graves' disease who became pregnant during the period from 1988 to 1998 after receiving radioiodine treatment at Ito Hospital. 25 of the 45 subjects had had a relapse of hyperthyroidism after surgical treatment for Graves' disease. 19 pregnancies were excluded because of artificial or spontaneous abortion. In the remaining 44 pregnancies of 35 patients, neonatal hyperthyroidism developed in 5 (11.3%) pregnancies of 4 patients. Serum levels of TRAb at delivery were higher in patients whose neonates suffered from hyperthyroidism (NH mother) than those of patients who delivered normal infants (N mother). Furthermore, serum levels of TRAb in NH mother did not change during pregnancy, although those of 4 patients of N mother, in which serum levels of TRAb before radioiodine treatment were as high as in NH mother, decreased significantly during pregnancy. In conclusion, women who delivered neonates with hyperthyroidism following radioiodine treatment seem to have very severe and intractable Graves' disease. Persistent high TRAb values during pregnancy observed in those patients may be a cause of neonatal hyperthyroidism.

TSH-receptor antibodies determined by the first, second and third generation assays and thyroid-stimulating antibody in pregnant patients with Graves' disease

The measurement of TSH receptor antibody (TRAb) has been recommended to predict the risk of neonatal hyperthyroidism (NH) in pregnant women with Graves' disease (GD). For the first generation TRAb (TRAb1) assay with commercial kit (Brahms, Berlin, Germany; or Cosmic co., Tokyo, Japan) an arbitrary limit of 40 U/l or 50% was suggested to indicate risk when measured late in pregnancy. In order to substitute TRAb1 with the second generation TRAb using porcine TSH receptor (pTRAb2) and human recombinant TSH receptor (hTRAb2) and the third generation TRAb (TRAb3) assay for this purpose, we measured TRAb in these four methods late in pregnancy in a total of 62 pregnant women with Graves' disease. The data showed that no cases with TRAb1 >50% has been missed if the TRAb1 assay was replaced by the pTRAb2, hTRAb2 or TRAb3 assay using their equivalent cut-off value of 70%, 10 IU/l, and 75%, respectively, but that an additional group of women would have been included in the risk group, especially in the TRAb3 assay. Next, the effect of maternal TRAb on thyroid function of offspring was studied in the 47 pregnant women with GD (43 with TRAb1 <50% and 4 with TRAb1 >50% during late pregnancy). In 2 women who gave birth to hyperthyroid children at days 6 and 14 of life, the maternal sera had strongly positive levels of TRAb1 (73.5% and 84.1%), pTRAb2 (84.9% and 91.5%), hTRAb2 (40.68 IU/L and 89.70 IU/L) and TRAb3 (92.1% and 93.5%) late in pregnancy, with one case displaying high positive (1114.3%) thyroid stimulating antibody (TSAb) level and the other case had moderate positive (433%) TSAb level. Of the remaining 45 women, 43 had TRAb1 <50% and the other 2 had TRAb >50% including 1 with low TSAb positive and 1 with positive thyroid stimulating blocking antibody (TSBAb) and negative TSAb; all of them gave birth to euthyroid children. Finally, a serial study regarding TRAb in 23 women with Graves' disease during pregnancy showed that TRAb1, pTRAb2, hTRAb2, TRAb3 value and TSAb level decreased significantly as pregnancy progressed. In conclusion, the present study supported TRAb as a useful marker to predict the risk of NH.

Management of Graves' disease during pregnancy: the key role of fetal thyroid gland monitoring

BACKGROUND

Fetuses from mothers with Graves' disease may experience hypothyroidism or hyperthyroidism due to transplacental transfer of antithyroid drugs (ATD) or anti-TSH receptor antibodies, respectively. Little is known about the fetal consequences. Early diagnosis is essential to successful management. We investigated a new approach to the fetal diagnosis of thyroid dysfunction and validated the usefulness of fetal thyroid ultrasonograms.

METHODS

Seventy-two mothers with past or present Graves' disease and their fetuses were monitored monthly from 22 wk gestation. Fetal thyroid size and Doppler signals, and fetal bone maturation were determined on ultrasonograms, and thyroid function was evaluated at birth. Thyroid function and ATD dosage were monitored in the mothers.

RESULTS

The 31 fetuses whose mothers were anti-TSH receptor antibody negative and took no ATDs during late pregnancy had normal test results. Of the 41 other fetuses, 30 had normal test results at 32 wk, 29 were euthyroid at birth, and one had moderate hypothyroidism on cord blood tests. In the remaining 11 fetuses, goiter was visualized by ultrasonography at 32 wk, and fetal thyroid dysfunction was diagnosed and treated; there was one death, in a late referral, and 10 good outcomes with normal or slightly altered thyroid function at birth. The sensitivity and specificity of fetal thyroid ultrasound at 32 wk for the diagnosis of clinically relevant fetal thyroid dysfunction were 92 and 100%, respectively.

CONCLUSION

In pregnant women with past or current Graves' disease, ultrasonography of the fetal thyroid gland by an experienced ultrasonographer is an excellent diagnostic tool. This tool in conjunction with close teamwork among internists, endocrinologists, obstetricians, echographists, and pediatricians can ensure normal fetal thyroid function.

One Case of Fetal and Neonatal Variable Thyroid Dysfunction in the Context of Graves’ Disease

Cases of maternal thyroid dysfunction are not always clearly identified during pregnancy. We report here the case of a 36-year-old patient with a history of treated Graves' disease whose child successively presented with a hypo- and hyperthyroid dysfunction that was difficult to treat despite the administration of synthetic antithyroid drugs and beta-blockers. The patient's thyroid hormone levels were normal during pregnancy, while still secreting anti-TSH-receptor autoantibodies. With time, these antibodies went from an inhibiting to a stimulating activity. Fetal monitoring using only ultrasonography had been proposed to the patient. With such a follow-up associated with fetal blood sampling it would have been possible to treat already in utero the thyroid dysfunction. The management of such patients is not limited to the follow-up of the maternal thyroid hormones, but should also evaluate the activity of the anti-TSH-receptor autoantibodies around the 28th week of amenorrhea and their effect on fetal blood. Fetal and neonatal thyroid dysfunctions have a major impact, but they can be detected and treated in utero. The clinical, laboratory and ultrasound follow-up makes it possible to monitor patients who are at risk and to propose a therapeutic and obstetrical management.

Fetal and neonatal thyroid function in relation to maternal Graves' disease

The abundance of published data on the neonatal effects of maternal Graves' disease (GD) contrasts with the paucity of information on fetal effects. In our yet unpublished study, we prospectively studied 72 pregnant women with a history of Graves' disease. Fetal ultrasonography was done at 22 and 32 weeks of gestational age. Fetal goiter was found at 32 weeks in 11 of the fetuses of the 41 mothers with positive TSH-receptor antibodies and/or antithyroid treatment and in none of the fetuses of the 31 other mothers. In the 11 fetuses with goiter, ultrasound findings (thyroid Doppler and bone maturation), fetal heart rate, and maternal antibody and antithyroid drug status effectively discriminated between hypothyroidism (n=7) and hyperthyroidism (n=4). One fetus with hyperthyroidism died in utero at 35 weeks from heart failure. Treatment was successful in the ten other fetuses. One fetus without goiter had moderate hypothyroidism at birth. This study showed that it is of the utmost importance to have the fetal thyroid scrutinized by an expert ultrasonographist and to have team work with obstetricians and paediatric endocrinologists in pregnant mothers with GD. This allowed us to accurately determine fetal thyroid status and to adapt the treatment in mothers successfully. Fetal hyperthyroidism does exist and needs an appropriate aggressive treatment.

Management of fetal thyroid goitres: a report of 11 cases in a single perinatal unit

Fetal thyroid goitres may reveal hormonal imbalance. This can jeopardize neurological development and fetal outcome even when early postnatal treatment is provided. We report a series of 11 goitres diagnosed antenatally in women with past or present thyroid disorders or discovered fortuitously on ultrasound scan. Fetuses presented with hyperthyroidism in three cases and hypothyroidism in eight. Hypothyroidism was iatrogenic in five cases, due to maternal anti-thyroid drugs. Hyperthyroidism was induced by transplacental transfer of thyroid stimulating antibodies (TSHrab). Accurate diagnosis of fetal thyroid status was obtained by fetal blood sampling but this invasive method was deemed necessary only in four cases as maternal clinical and biological data and ultrasound signs provided sufficient information to infer the type of thyroid disorder in the remaining patients. Fetal therapy relied on reduction of maternal antithyroid medication and, in selected cases, intra-amniotic injection of levothyroxin in hypothyroidism, and on administration of antithyroid drugs in hyperthyroidism. All newborns were healthy and none displayed consequences of severe thyroid imbalance. No caesarean section was performed for dystocia. Fetal thyroid goitres can be managed successfully with selected use of invasive diagnostic and therapeutic techniques.

Hyperthyroidism in early infancy: pathogenesis, clinical features and diagnosis with a focus on neonatal hyperthyroidism

Neonatal hyperthyroidism has mostly been described in the context of maternal Graves' disease. It has been estimated that about 0.2% of pregnant women have Graves' disease; however only 1% of the children born to these women are described as having hyperthyroidism. In most of the cases, the disease is due to maternal antibodies transferred from the mother into the fetal compartment, which stimulate the fetal thyroid by binding to the thyrotropin (TSH) receptor. In this form of neonatal hyperthyroidism, thyrotoxicosis disappears with the clearance of the maternal antibodies and usually signs disappear during the first 4 months of life. Rare forms of persistent, nonimmune neonatal hyperthyroidism are explained by molecular abnormalities of the TSH receptor. Prematurity is frequent, as well as hypotrophia. Tachycardia, goiter, hyperexcitability, poor weight gain, hepatomegaly and/or splenomegaly, stare and/or eyelid retraction are among the most frequent neonatal thyrotoxicosis clinical signs. Diagnosis is based on the determination of the blood level of thyroxine (T4), triiodothyronine (T3), and TSH. Even if these levels are normal in the cord blood, tests should be repeated 3 to 10 days later to detect possible delayed appearance of the disorder. These parameters should be interpreted according to the age of the neonate. To confirm the immune nature of this hyperthyroidism, thyroid-stimulating immunoglobulins (TSI) should be determined. The TSI determination is crucial in identifying nonimmune causes of neonatal hyperthyroidism: in this neonatal hyperthyroidism, TSI are not detected, either by radioreceptor assay and/or by functional assay, and molecular studies are needed to identify the mutation. Mutation of the TSH receptor leading to its constitutive activation and to neonatal hyperthyroidism have been described. Germline mutations are found in hereditary hyperthyroidism; de novo germline mutations can cause sporadic congenital hyperthyroidism.

Fetal thyrotoxicosis: a case report and recommendations for prediction, diagnosis, and treatment

A maternal history of Graves' disease places the fetus at risk for thyrotoxicosis in utero via the placental transfer of thyroid-stimulating immunoglobulins. Methods for prediction of fetal hyperthyroidism are available, but are not widely used. Clinical assessment of fetal thyroid status by monitoring of fetal heart rate and growth may be inaccurate. This raises some uncertainty in the initial diagnosis of fetal thyrotoxicosis and complicates the assessment of fetal response to maternal propylthiouracil therapy. A case illustrating these pitfalls in the diagnosis and management of fetal hyperthyroidism is presented. The condition was correctly diagnosed, but treatment based on fetal heart rate resulted in biochemical hypothyroidism in the infant at birth. Current recommendations for diagnosis and treatment of fetal hyperthyroidism are reviewed along with recent developments in the field. A modified approach is proposed.