title: Clinical courses of renal transplant recipients with high BK viremia.
abstract: OBJECTIVE
  We sought to investigate the clinical courses of renal transplant recipients with plasma BK viral loads >10(4) copies/mL.
  
  
  METHODS
  A single-center retrospective review was performed of 88 kidney transplant patients in whom high BK viremia (defined as plasma BKV load >10(4) copies/mL) was detected more than once from January 1, 2004, to December 31, 2011.
  
  
  RESULTS
  At the time of transplantation, the mean recipient and donor ages were 44.5 ± 11.1 and 43.9 ± 11.3 years, respectively, and 59 subjects (67.0%) were male. The median times to first BK positivity and high BK viremia after transplantation were 44 and 136 days, respectively. Within 3 months after transplantation, we detected, 56 cases of high BK viremia (63.6%). The mean duration of high BK viremia was 8.2 ± 7.7 months. When plasma BKV load was first >4 logs, the mean log BKV load was 5.50 ± 1.11 log copies/mL, which rose to a maximum of 5.82 ± 1.11. At these times, mean serum creatinine concentrations were 1.67 ± 0.79 and 2.64 ± 2.78 mg/dL, respectively. There were 31 cases (35%) of biopsy-proven BK nephropathy patients among 51 (58%) biopsies. Treatment modalities included discontinuation or dose reduction of mycophenolic acid drugs (n = 68) and switch from tacrolimus to cyclosporine (n = 9), cidofovir (n = 9), and leflunomide (n = 3). Based on the serum creatinine elevation after high BK viremia, patients were divided into group 1 (n = 27; 30.1%), whose maximal creatinine change was <0.5 mg/dL, and group 2, with a greater alteration. On multivariate logistic regression analysis, the maximal plasma BK viral load was significantly associated with a greater serum creatinine elevation (P < .001).
  
  
  CONCLUSIONS
  High BK viremia mostly occurred within 3 months after kidney transplantation. About 30% of renal allograft recipients with high BK viremia maintained stable renal function. Maximal plasma BK viral load was the only independent risk factor for high serum creatinine elevation.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: H
authors.initials: H
authors.lastname: Kim
authors.forename: W S
authors.initials: WS
authors.lastname: Yang
authors.forename: D J
authors.initials: DJ
authors.lastname: Han
authors.forename: S K
authors.initials: SK
authors.lastname: Park
mesh_terms: D000328:Adult; D001739:BK Virus / Q000302:isolation & purification*; D001706:Biopsy; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D019562:Viral Load; D014766:Viremia / Q000821:virology*
chemical_list: D007166:Immunosuppressive Agents