2023 Volume 72 Issue 1 Pages 105-114
The standardization of thyroid-related tests, such as TSH, FT4, and FT3, is clinically important since several guidelines for thyroid diseases recommend the therapeutic targets based on their absolute values. Since the thyroid-related tests are performed with an immunoassay, however, the absolute values are largely influenced by the analytical devices and reagents used for the assays. The International Federation of Clinical Chemistry and Laboratory Medicine Committee for Standardization of Thyroid Function Tests (IFCC C-STFT) promotes the standardization of FT4 and the harmonization of TSH, and the latter is now ongoing in Japan. However, at present, there are few reports comparing the absolute values yielded by multiple thyroid-related tests conducted simultaneously. In this study, we compared the precisions and correlations among four different methods, including those offered by Abbott, Siemens, Tosoh, and Fujirebio. We obtained favorable results on the precisions and correlations; however, we observed substantial discrepancies among the absolute values obtained by using different methods. These results suggest that harmonization especially on the absolute values is further required for thyroid-related tests in Japan.
