Elecsys TSH, FT4, T4, T-uptake, FT3 and T3. Clinical results of a multicentre study.

6 assays for the assessment of thyroid function (TSH, FT4, T4, T-uptake, FT3 and T3) were targets of the International Multicenter Study on the random access analyzer Elecsys 2010. The aim of the study was to characterize the clinical performance of the assay in method comparison and reference range studies. The assays under evaluation were compared to a broad variety of radio isotopic and non-radio isotopic assays. They are suitable for serum and plasma samples. In case of TSH the study include 2nd and 3rd generation TSH procedures. In general, good to excellent correlations were found between the Elecsys and the respective routine methods. Systematic deviations were extraordinary low in case of TSH, FT4 and T4. Regarding the analysis of T3 and FT3 some systematic deviations in terms of standardization have been observed. Results of Elecsys T4 and Elecsys FT4 were independent of the serum total protein or serum albumin concentrations. In T3 and FT3 Elecsys the results of samples from NTI (non-thyroidal-illness) patients were decreased, reflecting the physiological situation in these patients. Studies using samples from healthy euthyroid as well as untreated hypo- and hyperthyroid individuals enabled us to assess the assays reference ranges.