Prediction of Later Development of Transient Thyrotoxicosis in Neonates Born to Mothers with Graves Disease

Abstract

Neonatal thyrotoxicosis is thought to be induced by transplacental transfer of maternal TSH receptor antibodies (TRAb). We analyzed the relationship between the serum TRAb levels at birth and the development of thyrotoxicosis in neonates born to mothers with Graves disease. Thirty-three neonates born to mothers with Graves disease were eligible for the study. The thyroid function tests were performed with neonatal serum within 24 h after birth. The subjects were divided in two groups: neonates developed to thyrotoxicosis (Group A) and those not to thyrotoxicosis (Group B). Five neonates developed to thyrotoxicosis. There were no significant differences in free T₃, free T₄ and TSH concentrations in the blood of neonates within 24 h after birth between Group A and Group B. TRAb values were 75.0 ± 9.9% and 19.3 ± 2.6% in Group A and Group B, respectively (p<0.01). All 4 neonates with serum TRAb levels above 50% had developed to thyrotoxicosis. Serum TRAb of the other one neonate who developed to thyrotoxicosis was 26.0% on the 30th day after birth. Neonatal thyrotoxicosis can be predicted in neonates with high TRAb values. These results suggest that the screening of TRAb is useful for predicting thyrotoxicosis in neonates born to mothers with Graves disease.