Measures both Thyroid Stimulating Immunoglobulin (TSI) and Thyrotropin Binding Inhibitory Immunoglobulin (TBII), but does not provide information about function. The Thyrotropin Receptor Autoantibody (TRAB) Assay has utility in the differential diagnosis of Graves disease versus toxic nodular goiter. A low-positive TRAB (15-60) upon initial diagnosis is indicative of a high likelihood that a 6-18 month course of anti-thyroid drug medication will result in remission of Graves disease. Conversely, a high-positive TRAB (>80) upon initial diagnosis indicates a low likelihood of disease remission following anti-thyroid therapy. Studies show that 83% of patients with detectable receptor antibody activity (i.e., an elevated TRAB) at the end of a twelve month course of anti-thyroid drug therapy subsequently relapse. Non-elevated TRAB concentrations after twelve months of drug treatment predict remission in 89% of patients at 1 year and in 81% at 3 years after drug withdrawal. In the most current studies, the frequency of an elevated TRAB in patients with confirmed Graves disease ranges from 94-100%. Test sent to Mayo Medical Laboratories.