New assays of TSH-receptor antibodies: analytical and clinical performances in the diagnosis of Graves' disease

Graves' disease autoimmunity is attributable to the presence of serum antibodies (Ab) directed against the TSH receptor (TSHR) measured by a second generation (2G) assay using the human TRAK (hTRAK) with a high sensitivity in the diagnosis of Graves' disease. In this study, we have compared both analytical and clinical performances of hTRAK with those of five new methods using a porcine TSHR: two 2G methods and three assays using the monoclonal M22 directed against the TSHR pocket. We showed a bad reproducibility of these new methods with inter assay CVs higher than 10%. High clinical sensitivity and specificity that appeared similar to those of the hTRAK and next to 100% were observed except for a 2G method that failed to detect five Graves' patients. All these new methods should be avoided since they display a high variability despite their calibration against the same International Standard 90/672. The TRAKh using a human TSHR should be still used for a correct interpretation of results in the follow-up of Graves' disease.