Remission of Graves' hyperthyroidism predicted by smooth decreases of thyroid-stimulating antibody and thyrotropin-binding inhibitor immunoglobulin during antithyroid drug treatment

It is important to know whether a patient with Graves' disease will get int o remission or not during antithyroid drug (ATD) treatment. Thyrotropin (TS H) receptor antibodies (TRAb) cause Graves' disease. Thyroid-stimulating an tibody (TSAb) and TSH-binding inhibitor immunoglobulin (TBII) have been mea sured as TRAb to diagnose Graves' disease and to follow Graves' patients. S mooth decreases of TSAb and TBII during ATD treatment predict the remission of Graves' hyperthyroidism. We followed serial changes of TSAb and TBII in 58 Graves' patients before, during, and after ATD treatment; TSAb was meas ured as a stimulator assay, using porcine thyroid cells, and TBII as a rece ptor assay. Patterns of TSAb and TBII changes during ATD treatment differ f rom one patient to another. TSAb and TBII activities decreased and disappea red in 52 (group A) but continued to be high in the other 6 (group B); 39 o f the 52 group A patients achieved remission, but all of the 6 group B pati ents with persistently positive TSAb and TBII continued to have hyperthyroi dism. No differences in the initial TSAb and TBII activities were noted bet ween the 52 group A patients and the 6 group B patients. Of the 52 group A patients in whom TSAb and TBII had disappeared, 44 had smooth decreases of TSAb and TBII (group Al), and 8 had complex changes of TSAb and/or TBII (gr oup A2); 36 of the 44 group Al patients (82%) but only 3 of the 8 group A2 patients (37%) continued to be in remission more than 1 year after ATD disc ontinuation. The number of remission in group Al was significantly larger t han that in group A2. No differences in the initial TSAb and TBII activitie s were noted between group Al and group A2. More than 80% of group Al patie nts, who had smooth decreases of TSAb and TBII, continued to be in remissio n longer than 1 year. We demonstrated that smooth decreases of TSAb and TBI I during ATD treatment predicted the remission of Graves' hyperthyroidism. The Graves' patients can be classified into Al, A2, and B groups according to the patterns of TSAb and TBII changes during ATD treatment. Group Al pat ients, who had smooth decreases of TSAb and TBII, had higher rate of remiss ion than the others. Smooth decreases of TSAb and TBII during the early pha se of ATD treatment are a reliable predictor of the remission.