Objectives: To verify the cut-off values and to determine the clinical sensitivity of antithyroglobulin (TgAb) determinations using our routine RIA and the new electrochemiluminescent Elecsys assay.
Design and methods: We used the DYNOtest anti-Tgn manual RIA from BRAHMS and the new automated Elecsys electrochemiluminescent immunoassay from Roche Diagnostics. We analyzed 452 sera from the following subjects: 193 euthyroid controls, 163 with treated and untreated autoimmune thyroid diseases (AITD) (108 Graves' disease and 55 thyroiditis), 50 with differentiated thyroid carcinoma, 13 with nonautoimmune thyroid disease and 33 with type 1 diabetes mellitus.
Results: As expected, using the proposed thresholds (BRAHMS 60 kIU/L, Elecsys 115 kIU/L) approximately 6% of the control subjects were positive for TgAb with both methods. In AITD patients, the sensitivity of TgAb determination was significantly higher with the Elecsys assay (51.5%) than with the BRAHMS assay (39.3%). This difference was not observed in the other patient groups.
Conclusion: The Elecsys assay can be preferred not only because it is automated and rapid, but also because of its better clinical performance in AITD patients.