Clinical significance of assay of thyroid-stimulating antibody in Graves' disease.

We correlated thyroid-stimulating antibody (direct thyroid stimulation method) with the clinical course of 187 patients with Graves' disease. Of 64 patients with newly diagnosed hyperthyroidism, 59 were positive; 36 of 38 patients tested early in therapy were positive. Twenty-eight patients received antithyroid drug therapy, and thyroid-stimulating antibody was measured at cessation of therapy; 13 patients, negative in the assay, remained in remission, and of 15 relapsed cases 12 were positive. Of 57 patients previously treated by various means for hyperthyroidism, 34 were positive, and they primarily had had relapse after initial treatment, then ablative therapy causing hypothyroidism. Six of 10 patients with euthyroid ophthalmopathy had a positive assay and an abnormal thyrotropin-releasing hormone (TRH) test or thyroid suppression test; the four negative patients had a normal TRH test. Thus measurement of thyroid-stimulating antibody appears effectively to reflect activity of the underlying disturbance in Graves' disease.