PREDICTION OF NEONATAL HYPERTHYROIDISM IN INFANTS BORN TO MOTHERS WITH GRAVES-DISEASE

Objective: To determine whether determinations of thyrotropin-receptor antibody (TRAb) levels in newborn infants of women with Graves diseas e would predict which infants will have hyperthyroidism. Methods: The TRAb levels, assayed in the sera of 14 infants born to 14 women with G raves disease, were measured sequentially in the infants with hyperthy roidism during the course of antithyroid medication therapy. Results: Seven infants had TRAb values less than 0.15 and remained euthyroid. I n seven infants whose initial TRAb values were more than 0.25 (range, 0.48 to 0.88), clinical and biochemical signs of hyperthyroidism devel oped. The infants were treated with antithyroid medication until day 5 7 to day 123 of life. Therapy was discontinued when the infants were f ree of symptoms and when serum thyroxine and triiodothyronine and free thyroxine levels remained normal during therapy with decreasing doses of antithyroid medication. When the medication was discontinued, TRAb values were less than 0.20. Conclusions: Infants born to mothers with Graves disease with initial TRAb values less than 0.15 remained euthy roid. The TRAb values greater than 0.25 were associated with the devel opment of neonatal hyperthyroidism. During treatment of neonatal hyper thyroidism, TRAb values less than 0.20 may be helpful in deciding when to withdraw antithyroid medication.