Abstract
Tacrolimus, an immunosuppressive drug has been used for many indications, including posttransplant immunosuppression and autoimmune diseases. Because of the increasing number of patients in whom the blood tacrolimus level needs to be maintained at low concentrations, we changed the assay method to chemiluminescent immunoassay (CLIA). For evaluating this assay method, we examined the correlations among results obtained by three methods, enzyme multiplied immunoassay technique (EMIT), CLIA (two instruments), and electro-chemi luminescence immunoassay (ECLIA), and assessed the precision of each method. Satisfactory results in regard to the within-run reproducibility, between-run reproducibility, specimen stability, and dilution linearity were obtained for all three methods. In regard to correlations among the results, no clear correlations were obtained, presumably because of the differences in the measurable range among the methods. From the regression equation, a tendency toward providing higher values was observed for EMIT as compared to the other methods. Instruments can have various characteristics, such as a tendency toward providing higher values and a possibility of being affected by cross reactivity. We wish to contribute to improvement of the treatment results by improving the sensitivity, accuracy, and precision while taking these characteristics into consideration.
