[Serum thyrotropin binding inhibitory immunoglobulin (TBII) activity before and after subtotal thyroidectomy in Grave's disease].

Serum level of TBII activity was measured in 81 patients with Graves' disease by the Smith's radioreceptor assay method and the activity more than +15% was designated as "positive". All the patients had been under medical treatment with antithyroid drugs and 71 of them underwent subtotal thyroidectomy. The negative TBII activity was seen in 4 (22%) of 18 patients in whom the duration of antithyroid drug treatment was less than 2 years and in 6 (60%) of 10 patients whose medical therapy was for more than 2 years. TBII activity was not correlated with serum MCHA-, TGHA-titers and circulating lymphocyte counts, but correlated well with the degree of lymphoid cell infiltration in the resected thyroid tissue. All the 7 patients was negative had never relapsed, but 2 of them remained at the euthyroid state 6 to 24 months after operation, 3 hypothyroid and 2 at a borderline between the normal and hypothyroid. The postoperative states of the 13 patients who showed positive TBII activity before operation were euthyroid in 7, hypothyroid in 2, borderline hypothyroid in 4 and relapse in one. A gradual decline of TBII activity following surgery was generally associated with postoperative euthyroidism. It is concluded that determination of TBII activity is of help to estimate the thyroid functional state in Graves' disease.