Performance evaluation of tacrolimus reagent using ACMIA method and necessity of external survey

Abstract

The principle of tacrolimus measurement using the Dimension series is based on the ACMIA method, with which the pretreatment deproteinization operation is automated. We evaluated the performance of the tacrolimus reagent with modification of the method to improve tacrolimus binding to antibodies and magnetic particles, as well as improve tacrolimus reactivity with metabolites. As a result of investigating reproducibility (simultaneous, within-day difference), dilution linearity, effect of coexisting substances, limit of blank, limit of detection, limit of quantification and correlation, we found that results varied with low reproducibility (within-day difference). Moreover, Dimension showed about 10% higher correlation than ARCHITECT and Cobas8000. When the blood collected did not reach the specified amount, the measured value tended to be low owing to the increase in the concentration of EDTA-2K, but this effect was reduced by further improvement of the reagent. However, because the improvement remains incomplete, it is necessary at present to collect the specified amount of blood.