P01 ANALYTICAL AND CLINICAL EVALUATION OF A NEW THIRD-GENERATION IMMUNOASSAY FOR THYROTROPIN RECEPTOR AUTOANTIBODIES

Background and Objective. Hyperthyroidism in Graves' disease is caused by autoantibodies to the TSH receptor (TSHR), and TSHR autoantibody (TRAb) measurement yields important information to diagnose and decide on the course of treatment of Graves' disease, to evaluate risk of relapse after withdrawal of anti-thyroid drug therapy, and risk of fetal and neonatal hyperthyroidism. The latest generation of assays detects TRAb in around 95% of unselected patients with newly diagnosed Graves' disease. We evaluated basic and clinical performance of a new, rapid, and fully automated electrochemiluminescence immunoassay Elecsys Anti-TSHR (Elecsys TRAb) for measuring serum TRAb, based on the ability of TRAb to inhibit the binding of a human thyroid-stimulating monoclonal antibody (M22). We compared the performance of this new third-generation porcine thyroid receptor antibody (TRAb) method with the conventional TRAb assay based on the human recombinant TSH receptor. Materials and Methods. All the sera was measured with the automated Elecsys TRAb assay on the platform Modular Analytics E170 (Roche Diagnostics). For evaluation of basic performance of the assay, we carried out interassay precision studies using three serum pools, tested in five different days, with a values near the cut-off point (1.5 IU/L). We measured TRAb concentrations of sera from 40 patients; the results was compared with radioreceptor method using the hTRAK (Brahms) Clinical performance of the assay was evaluated with Graves' disease patients and normal subjects; the results was compared with a radio-receptor assay ( 14 U/L positive for TRAb) (RIAZEN