Failure of Anti-TSH Receptor Antibodies (TRAb) to Predict the Outcome of the Course of Graves' Disease Following Withdrawal of Antithyroid Drug

Abstract

Nineteen patients with Graves' disease were regarded as euthyroid at the end of therapy. Follow-up studies were performed for further 3 years. TSH binding inhibitor immunoglobins (TBII) were measured by radioreceptor assay. Thyroid stimulating antibodies (TSAb) were measured by a sensitive cAMP accumulation using FRTL-5 cells. Most of the patients showed negative TBII at the end of therapy, while TSAb-positive patients were approximately 50%. The relapse rates during post therapeutic period were 33.3% in TSAb-positive group and 40% in TSAb-negative group, which were not significantly different between the two groups. It was thought that determination of TSAb activity at the end of therapy, in addition to TBII, appears to play a permissive role in predicting the outcome of the course of Graves' disease following discontinuation of antithyroid drug therapy.