A search for prognostic index in the treatment of hyperthyroidism

Studies of serum thyroid-stimulating antibody (TSAb) levels and other indices of thyroid status were performed on patients with Graves' disease currently on antithyroid drugs, freshly diagnosed patients with Graves' disease and relatives of patients with Graves' disease. Of 25 patients with Graves' disease currently on anti-thyroid drugs, 12 were initially TSAb-positive and 13 TSAb-negative. At the end of medication 6 initially TSAb-positive patients were still positive and all soon relapsed; all initially TSAb-negative patients were still negative. Of 18 patients TSAb-negative at the end of medication 16 remained negative, while 2 became positive and relapsed. All of 15 freshly diagnosed patients with Graves' disease were TSAb-positive. All of 79 relatives of patients with Graves' disease were TSAb-negative, regardless of their thyroid status as judged by other indices. It is concluded that TSAb levels as measured by the direct in vitro thyroid stimulation assay of McKenzie and Zakarija provide a sensitive index for prognosis of the clinical course of hyperthyroidism in Graves' disease. Earlier reports of TSAb or long-acting thyroid stimulator (LATS) activity in the sera of euthyroid relatives of such patients were not confirmed