Performance of Opus immunoassays for thyroxine and beta-human chorionic gonadotrophin in serum.

Two representative immunoassays for measuring thyroxine and beta-subunit of human chorionic gonadotrophin in serum, using the Opus immunoassay analyzer, were evaluated by comparing them to the reference RIA for T4 and beta-HCG enzyme immunoassay. Both assays were superior in accuracy and precision than the reference methods and exhibited good linearity throughout the concentration range needed for discriminating abnormally low and elevated concentrations from the established reference ranges of thyroxine and beta-human chorionic gonadotrophin in serum. Correlation between the results of the Opus immunoassays and the reference assays for T4 and beta-HCG was very good with correlation coefficients of 0.92 and 0.98, respectively.