[Predictive value of thyrotropin receptor antibodies using the second generation TRAb human assay after radioiodine treatment in Graves' disease]

The detection of TSH-receptor antibodies (TRAb) in patients with Graves' disease is routinely used in nuclear medicine laboratories. This determination has been possible for approximately 3 years with a second generation human TRAb assay. Studies showed that this TRAb determination is diagnostically more sensitive compared to established, porcine TRAb assays.The aim of our study was to investigate, based on a ROC analysis, whether TRAb determination with the new, second generation assay allows a dependable statement about probability of occurrence of relapse after radioiodine therapy in patient suffering from Graves' disease.57 patients were examined with the DYNOtest TRAKhuman (BRAHMS Diagnostica AG, Hennigsdorf) directly before and six months after therapy with radioiodine (dose: 150 Gy). A ROC-analysis was performed to determine positive/negative predictive values depending on different cut-off values.Whereas 21/57 patients became eu- or hypothyroid after six months, 36/57 patients relapsed. Non-relapsed patients showed a significant lower median TRAb titer (4.2 IU/l vs. 19.2 IU/l; p0.05) compared to relapsed patients. But the positive predictive value conducted 63 and 66, 62 and 66 as well as 63 and 69% (before and after therapy) linked with the cut-offs 1.0, 1.5, and 2.0 IU/l. So it was in areas also achieved by the first generation porcine radio receptor assay.An increased sensitivity is achieved undoubtedly with the new DYNOtest TRAKhuman in the diagnostic of Graves' disease. It is not held over the established radio receptor assay concerning the positive predictive value for relapsing patients.