From the Guidelines
BK virus detected in the urine of a liver and kidney transplant recipient indicates potential viral reactivation, which requires prompt attention to prevent BK virus nephropathy and potential graft loss. The presence of BK virus in urine suggests that the patient is at risk of developing BK virus-associated nephropathy (BKVAN), a condition that can lead to renal allograft dysfunction and loss 1. According to the KDIGO clinical practice guideline, screening for BKV with quantitative plasma NAT is recommended at least monthly for the first 3-6 months after transplantation, then every 3 months until the end of the first post-transplant year, and whenever there is an unexplained rise in serum creatinine 1.
Key Considerations
- Reducing immunosuppressive medications is suggested when BKV plasma NAT is persistently greater than 10,000 copies/ml 1
- Specific antiviral strategies may be needed for patients with significant viral loads or evidence of nephropathy, including switching from tacrolimus to cyclosporine, reducing mycophenolate dosage, or considering leflunomide or cidofovir 1
- Regular monitoring of viral load in urine and blood is essential, with measurements every 2-4 weeks until improvement 1
Monitoring and Treatment
- The American Society of Transplantation recommends routine monitoring for BK virus in all kidney transplant immunosuppression trials, using a quantitative nucleic acid-based viral load assay of urine and/or blood 1
- Treatment typically involves reducing immunosuppression as the first step, carefully balancing the risk of rejection against viral control 1
- Liver transplant recipients are less commonly affected by BK virus-related complications, but monitoring remains important due to the dual transplant status 1
From the Research
BK Virus Infection in Transplant Patients
- BK virus (BKV) infection is a significant concern in transplant patients, particularly those who have undergone kidney transplantation 2, 3, 4.
- The presence of BKV in urine can indicate BKV-associated nephropathy (BKVAN), a condition that can lead to allograft dysfunction or loss 2, 3, 4.
Risk Factors and Diagnosis
- Male sex has been identified as a risk factor for BKVAN development after kidney transplantation 2.
- The diagnosis of BKVAN is typically made by a renal allograft biopsy, although it can be challenging due to pathological similarities with acute cellular rejection 4.
- Screening protocols for early detection and prevention of symptomatic BKV nephropathy have improved outcomes 3.
Treatment and Management
- Reduction in immunosuppression is generally advocated as the initial therapeutic option for the management of BKVAN 4.
- Antiviral agents such as cidofovir, leflunomide, and quinolones have been used to treat BKVAN, although their effectiveness can vary 3, 4.
- Persistent BKV viremia may be related to renal dysfunction in liver transplant patients 5.
BKV Infection in Liver Transplant Patients
- BKV infection has been detected in liver transplant recipients, with a frequency of 21% for viruria and 18% for viremia 5.
- BKV viremia was more common among patients experiencing a rejection episode, and persistent viremia may be related to renal dysfunction 5.