Clinical studies on abnormal thyroid stimulators in patients with Graves' disease. II. Clinical significance of measuring TSAb and TBII in patients with euthyroid Graves' disease and patients with hyperthyroid Graves' disease during antithyroid drug treatment

To evaluate the clinical significance of TBII and TSAb activities in euthyroid and hyperthyroid Graves' disease, these two activities were measured in 8 patients with euthyroid Graves' disease and 29 patients with hyperthyroid Graves' disease during treatment with antithyroid drugs. In 8 patients with euthyroid Graves' disease, TBII activity was detectable only in one patient and TSAb activity detected in 3 patients, these detectabilities being much lower than those in hyperthyroid Graves' disease. However, 2 of 4 patients who had either TSAb or TBII came to have both activities, and one of them became overt hyperthyroid. In patients with hyperthyroid Graves' disease, detectabilities of these activities became lower as they became euthyroid with antithyroid drug treatment, but TSAb tended to be higher than TBII when they remained euthyroid for more than 4 months. Although the majority of the patients who had TSAb and/or TBII activities were T3 non-suppressible, patients with no TSAb and TBII activities did not necessarily show remission of the disease. The present results suggest that patients with euthyroid Graves' disease with both TBII and TSAb may be apt to become hyperthyroid, and that TSAb and TBII activities and T3 suppressibility may not be a definite criteria for the remission of Graves' disease.