Diagnosis and treatment of BK virus-associated nephropathy after renal transplantation

Objective To explore the diagnosis and treatment of BKV nephropathy after renal transplantation. Methods A total of 62 patients with progressive creatinine elevation were routinely examined by blood and urine BKV-DNA. And 21 patients with positive results underwent graft biopsies for confirming a diagnosis. Results Among 21 cases of BKV infection, 20 cases received leflunomide in replacing mycophenolate mofetil (MMF) and a lower dose of tacrolimus. One case with urine (-) & blood (+ ) received sirolimus in replacing tacrolimus and a lower dose of MMF. Among 11 cases with urine (+ ) and blood (-), urinary BKV-DNA turned negative & creatinine decreased markedly (n=4), urinary BKV-DNA load decreased & creatinine stablized (n=4), death from pulmonary infection with hepatic & renal failure (n=1), urine BKV-DNA load decreased & creatine increased (n=1), BKV–DNA load was not re-examined in 1 case of acute rejection and hydronephrosis with elevated creatine; Among 9 cases with urine (+ ) & blood (+ ), blood BKV-DNA turned negative with urinary BKV-DNA load & creatine decreased (n=6), blood BKV-DNA load decreased & creatine stablized (n=2) and no re-examination with a stable level of creatine (n=1); One case with urine (-) & blood (+ ) was not timely treated and ultimately leading to graft loss after an onset of acute rejection. Conclusions BKV nephropathy may be effectively treated by decreasing immunosuppressive intensity. However, clinicians should stay on a high alert for acute rejection due to an excessive reduction of immunosuppressive agents. Key words: Kidney transplantation; BK Virus; Acute rejection