Clinical Evaluation of a New Automated Bridge Assay for the Detection of Thyroid-Stimulating Hormone Receptor Autoantibodies.

Graves' disease is an autoimmune disease caused by autoantibodies to the thyroid-stimulating hormone receptor, which usually leads to hyperthyroidism in these patients. The aim of the present study was to evaluate a new automated bridge chemiluminescence thyroid-stimulating hormone receptor autoantibody assay for the diagnosis and in the follow-up of Graves' disease patients and to compare this assay with another established competition assay. Altogether, 132 Graves' disease, 39 autoimmune thyroiditis, 28 non-autoimmune nodular goiter and 27 thyroid cancer patients were included in this study. Receiver-operating characteristic plot analysis based on above mentioned samples revealed an area under the curve of 0.9994 (95% confidence interval: 0.9980-1.001), indicating high sensitivity and specificity of the assay. The optimal sensitivity (99.22%; 95% confidence interval: 95.7-99.8%) and specificity (98.98%; 95% confidence interval: 94.4%-99.8%) were seen at a cut-off level of 0.550 IU/L. The corresponding positive predictive value was 99.22%, whereas the negative predictive value was estimated to be 98.98%. A detailed comparison of the two assay systems used revealed a slightly different thyroid-stimulating hormone receptor autoantibody distribution with the new bridge assay detecting more thyroid-stimulating hormone receptor autoantibody-positive follow-up patients with active Graves' disease compared with the competition assay. The measurement of thyroid-stimulating hormone receptor autoantibodies revealed a steady decline over the time of follow-up. In summary, our results demonstrate that the new automated bridge assay for detecting thyroid-stimulating hormone receptor autoantibodies has high sensitivity and specificity for diagnosing Graves' disease and to discriminate from other thyroid diseases, respectively.