Transplant kidney biopsy for proteinuria with stable creatinine: Findings and outcomes

Introduction: Little is known aboutbiopsy findings and outcomes when kidney transplant recipients (KTRs) undergo biopsy for isolated proteinuria with stable serum creatinine (SCr). Methods: We analyzed all KTRs who underwent biopsy for isolated proteinuria with stable SCr between January 2016 and June 2020. Patients were divided into three groups based on the biopsy findings: Active Rejection (AR), Glomerulonephritis (GN), and Other. Results: A total of 130 KTRs fulfilled our selection criteria; 38 (29%) in the AR group, 26 (20%) in the GN group, and 66 (51%) in the Other group. Most baseline characteristics were similar between the groups. In multivariate analysis, higher HLA mismatch (HR per mismatch: 1.30; 95% CI:1.06–1.59; P =.01) and male gender (HR:.45; 95% CI.23–.89; P =.02) were associated with AR. There was no significant correlation between the degree of proteinuria and rejection (r =.05, P =.58) or GN (r =.07, P =.53). Graft survival was also similar between the groups. Likely due to the early diagnosis without a significant rise in SCr, outcomes were similar among all three groups. Conclusion: Routine monitoring for proteinuria followed by a biopsy and appropriate management may help to identify early acute graft injury and prevent graft failure.