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.

Thyroid function during pregnancy in women with past Graves' disease

Graves' disease and thyroid dysfunction during pregnancy can lead to maternal and fetal complications. No information is available on thyroid function in women with a past history of Graves' disease. We compared free T3, free T4 and TSH in a group of pregnant women with a history of resolved Graves' disease requiring no current treatment (n= 34) and in a group of pregnant controls (n= 102). We found no significant differences in the levels of these hormones between the two groups. Women with a past history of Graves' disease and no current treatment display a normal thyroid function and adaptation during pregnancy.

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.

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.