Impact of CYP3A5 genetic polymorphism on cross-reactivity in tacrolimus chemiluminescent immunoassay in kidney transplant recipients

► We evaluated the cross-reactivity in tacrolimus CLIA in kidney transplantation. ► CYP3A5*3 affected the metabolic pathway of tacrolimus and its blood level. ► Blood tacrolimus level measured by CLIA was 35% higher than that by LC-MS/MS. ► A higher cross-reactivity was found in patients with a tacrolimus level of < 3 μg/l. ► A higher cross-reactivity was found in patients with the CYP3A5*1 allele.