Clinical validity of a new commercial method for detection of TSH-receptorbinding antibodies in sera from patients with Graves' disease treated withantithyroid drugs

In this work, we compared the activities of TSH binding inhibitory immunogl obulin (TBII) results obtained with a new human TBII assay (h-TBII) using t he human recombinant TSH receptor with thyroid stimulating antibodies (TSAb s). Sera were obtained from 90 patients with Graves' disease before and aft er therapy with carbimazole (1-methyl-2-thio-3-carbethoxyimidazole). Before treatment. h-TBII were detected in 89/90 patients (98.9%) whereas TSAb act ivity was: positive in 88/90 patients (97.7%). The two parameters fill duri ng therapy. At the end of treatment, only h-TBII levels were significantly different between patients in remission and those in relapse (Z=2.212 P=0.0 270). The relapse rate in the patients with positive antibodies at drug wit hdrawal was significantly increased (chi (2) =6.057; P=0.0139 for h-TBII an d chi (2) =8.988: P =0.0021 for TSAb). Most of patients (76%) relapsed duri ng the 2 years following drug withdrawal. h-TBII or TSAb values were positi ve in 84.6% or in 80.8% of patients at the time of relapse. There was a sig nificant correlation between the two antibody measurement methods before tr eatment, at drug withdrawal and at the time of relapse. These results indic ate that the new TBII assay using human TSH receptor is as sensitive as: th e TSAb assay. Because of its much easier performance, it may advantageously replace TSAb measurement especially for the Craves. disease diagnosis and in the prediction of short-term relapse at the end of treatment. (C) 2001 E lsevier Science B.V. All rights reserved.