2017 Volume 66 Issue 3 Pages 242-247
The dimension RxL tacrolimus (TACR) assay, using affinity column mediated immunoassay (ACMIA), was reported to show a relatively large variation in the low-concentration range. In this study, we evaluated the analytical performance of the improved dimension tacrolimus (TAC) assay. The within-run and between-day precisions were obtained as 3.1–6.2% and 2.8–5.7%, respectively. The limits of quantitation of the TAC and TACR assays were determined to be 1.1 and 2.6 ng/mL, respectively. Dilution linearity was found up to nearly 30.0 ng/mL. In a comparison study, the correlations between the TAC and TACR assays were n = 79, r = 0.959, and y = 1.06x − 0.1. Note that EDTA whole blood samples were used in the measurements, and the influence of EDTA on the measurements was mentioned in the package insert. In the EDTA interference study, the tacrolimus concentration decreased to 42.3% at EDTA-2Na of 3.0 mg/mL, and this decrease was observed in a concentration-dependent manner. The dimension TAC assay showed good analytical performance. Regarding the limit of quantitation, the dimension TAC assay showed better performance in the low-concentration range than the dimension TACR assay. However, it is necessary to pay attention to the amount of blood collected because of the influence of EDTA concentration on tacrolimus concentration.
