Measurement of TSH Receptor Antibody in Pregnant Women with Graves’ Disease Predicts Thyroid Function of the Newborn

Abstract

We have attempted to clarify the significance of measurement of TSH receptor antibody (TRAb) in pregnant women with Graves’ disease to predict the development of neonatal Graves’ disease. The subjects were seventeen pregnant women with Graves’ disease and their newborns. Blood was taken from the pregnant women within two weeks before delivery and from the newborns within two weeks after birth. Thyroid function and TRAb of the newborns were followed. The correlation of TRAb between pregnant women and newborns was significant (n=12, r=0.8781, p<0.01). Four neonates developed hyperthyroidism. FT4 was elevated after a week in two neonates whose mothers had taken 6 tablets of PTU and 4 of MMI. Blood TRAbs in the umbilical vein from three neonates with hyperthyroidism were significantly high, 78%, 84% and 79%, and their TRAb levels were high at 2 months. One premature baby developed hyperthyroidism, even though his TRAb at 2 weeks was 36%. TRAb values of more than 70% in pregnant women predict the development of hyperthyroidism in newborns. The period of elevation of FT4 in neonates might be affected by antithyroid therapy to their mothers. SFD babies may develop hyperthyroidism, even if their TRAbs are less than 70%. This study shows the significance of TRAb measurement in pregnant women to predict the outcome of thyroid function in their babies.