Objective: To determine the course of thyrotropin (thyroid-stimulating hormone [TSH]) receptor antibodies (TRAbs) in children and adolescents with Graves' disease treated using antithyroid drugs (ATDs).
Design: Retrospective, cross-sectional study of 86 children and adolescents with Graves' disease treated medically for >3 years. Patients with Hashimoto's thyroiditis and idiopathic short stature (n = 30) served as controls. A second-generation enzyme-linked immunosorbent assay (ELISA) for TRAbs was used.
Main outcomes: Twenty-two out of 23 (95.7%) patients with newly diagnosed Graves' disease, but 0/30 controls, had detectable TRAbs (22.0 +/- 13.5 U/L [mean +/- SD] vs. 0.9 +/- 0.9 U/L, p < 0.0001). Mean TRAb levels decreased with duration of therapy, but even after 13-24 months, TRAbs had normalized in only 3/16 (18.8%) patients. The initial TRAb titer correlated significantly with severity of the initial hyperthyroidism, but did not predict the response to therapy as indicated by the dosage of ATD required to control the hyperthyroidism at 6 and 12 months.
Conclusion: Unlike adults, most children and adolescents with Graves' disease require >2 years of ATD treatment before TRAbs are normalized. Although initial TRAb activity reflects disease severity, it does not predict the response to medical therapy. Recommendations as to treatment duration developed for adult patients should not be applied to the young.