Study of Tacrolimus Calibrator and Reagent Matrix Effect

A specific drug concentration in the blood must be maintained for tacrolimus, which controls immune rejection in organ transplant patients. Therefore, monitoring it through accurate tests is important to confirm this level. This paper reports a case in which the quality control results differed according to the calibrator and reagent in the tacrolimus test. This laboratory performs a tacrolimus (FK-506) test using the Alinity I system. Multichem WBT was used as a quality control material. Quality control materials were installed in the equipment within 30 minutes of manual pretreatment. A comparison of the quality control results of calibrator lot number 46248FP00 and reagent lot number 46243FP00 with calibrator lot number 46248FP00 and reagent lot number 50450FP00 revealed a 16% difference in values between calibrator lot number 46248FP00 and reagent lot number 50450FP00. These results were attributed to differences between the reagents and calibration materials. Hence, manufacturers and laboratories need to prepare for this.