Evaluation of the Cobas Core system for use in routine diagnosis of thyroid disorders

The aim of this clinical study was to evaluate the TSH, FT4, FT3, T3, and T4 assays designed for use on the Cobas Core Immunoassay Analyzer. Performance of these enzyme immunoassays (EIAs) was compared with well established and routinely used radioimmunoassays (RIA) or immunoradiometric assay (IRMA). In the first part of the study, the between-run and within-run data as well as the linearity of the Cobas Core assays was carried out, showing a very high precision; most coefficients of variation (CVs) were below 8%. In the second part of the study, serum samples from patients with different thyroid diseases were evaluated, and the results compared with those obtained by RIA or by IRMA. All results were highly comparable with the clinical aspects of all investigated thyroid disorders, and the data of TSH, FT4, T3 and T4 were completely in concordance with those assessed by RIA or IRMA methods; however, only the FT3 assays had a moderately correlation. In contrast to RIA methods, Cobas Core EIAs provided precise results in patients with thyroid hormone transport protein anomalies or T4/T3 autoantibodies; moreover, elevated serum concentrations of thyroxine binding globulin (TBG) did not affect measurement of total thyroid hormone concentrations.