OBJECTIVETo explore the clinical diagnosis of BK virus (BKV) infection in renal transplant recipients.

METHODSUrine and peripheral blood samples were taken from 234 renal transplant recipients for BKV detection with cytological test and real-time PCR.

RESULTSThe occurrence rate of urine decoy cells, BKV viruria and viremia in these patients was 33.3 %, 33.3% and 16.2%, respectively, and the median level of urine decoy cells was 6/10 HPF, with the median level of urine and peripheral blood BKV of 7.62 x 10(3) copy/ml and 7.61 x 10(3) copy/ml, respectively. The positivity rate of BKV in the urine samples were significantly higher than that in peripheral blood samples (P=0.000). The amount of decoy cells was related to BKV load in the urine samples (gamma=0.59, P=0.000), but the BKV load in the urine samples was not related to that in peripheral blood samples (P=0.14).

CONCLUSIONRenal transplantation is associated with increased BKV shedding, indicating the necessity of BKV monitoring in renal transplant recipients with urine cytology, which is convenient and sensitive and indicates renal histological changes indirectly. Urine and peripheral blood BKV DNA detection is of value in identifying BKV activation to prevent irreversible graft damage of BKV-associated nephropathy.