Evaluation of the new Abbott®Alinity assay for the measurement of thyroglobulin antibodies in patients with differentiated thyroid carcinoma.

BACKGROUND: Measurement of antithyroglobulin antibodies (TgAb) is important in patients with differentiated thyroid carcinoma (DTC) with total thyroidectomy. These patients are monitored based on serum thyroglobulin (Tg) levels. TgAb is known to interfere with the measurement of Tg by immunoassay. This study evaluates a new methodology for the measurement of TgAb Alinity Abbott® and the concordance with other methods (first and second generation Advia Centaur Systems Siemens® and Phadia 250 Thermofisher®). METHODS: The technical characteristics of Alinity TgAb measurement methodology were analysed, with imprecision and repeatable studies. In order to assess concordance, a minimum of 69 and a maximum of 76 samples from patients with DTC and total thyroidectomy were processed in parallel by several TgAb measurement methodologies. Agreement rates were determined using kappa statistics. The correlation between the four methods was examined pairwise using McNemar test analysis. RESULTS: The coefficients of variation (standard deviation as a percentage of the mean % CV) for the Alinity Abbott kit reagent TgAb were within 10% included the functional sensitivity. On the other hand, the concordance analysis with the kappa index concluded substantial agreement. The McNemar test showed a significant difference between Alinity versus Centaur second generation (difference 8.33%, CI 95% 0.68-8.33, p = .0313). CONCLUSION: The new methodology for the measurement of TgAb meets the imprecision standards while presenting an adequate concordance agreement with other methodologies available in laboratories. It is important to define the functional sensitivity when reporting results so that they are as reliable as possible.