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.
Prospective observational study.
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.
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.
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.