BK virus viremia in a well‐ HLA ‐matched kidney transplant population mainly on low‐dose cyclosporine‐based immunosuppression

The incidence and clinical course of polyomavirus‐associated nephropathy ( P y VAN ) in our well‐ HLA ‐matched kidney transplant population mainly on low‐dose cyclosporine‐based triple‐drug immunosuppression has not been described in detail. We aimed to characterize our patients with P y VAN and BK virus ( BKV ) viremia. Among 166 kidney transplantations between J anuary 2007 and F ebruary 2011 followed up at H elsinki U niversity H ospital nephrology clinic, 136 were screened for BKV viremia by quantitative analysis of BKV DNA in plasma. P y VAN was diagnosed by biopsy histopathology and SV 40 T ‐antigen detection. BKV viremia or P y VAN were treated by reducing immunosuppression. BKV viremia was detected in 12 (9%) patients. P y VAN was diagnosed in six patients (4%). In the six patients with no P y VAN , four had low‐level viremia (<10 000 copies/mL) of short duration (<2 months), one had high‐level viremia, and one had sustained low‐level viremia. After reduction of immunosuppression, all except one patient were able to clear viremia. No grafts were lost due to P y VAN . Even in a low‐risk population, BKV viremia and P y VAN occur, highlighting the importance of monitoring viral loads. Reduction of immunosuppression was successful, and no grafts were lost due to P y VAN .