Transferrin saturation can serve as a novel biomarker for predicting the occurrence and development of BK virus-related nephropathy after kidney transplantation.

Background: It is unclear whether iron levels affect BKPyV reactivation after kidney transplantation. Our goal is to analyze the relationship between preoperative iron levels in kidney transplant recipients and postoperative BK virus reactivation. Additionally, we aim to develop and validate a personalized prediction model for BK virus reactivation. Methods: We retrospectively analyzed the relationship between preoperative iron levels and BK virus reactivation in 626 kidney transplant recipients. The cohort was randomly divided into a training cohort and a validation cohort in a 2:1 ratio. Independent risk factors associated with BK virus reactivation were identified in the training cohort using COX proportional hazards regression. Based on the analysis results, a nomogram was constructed to develop individualized risk prediction models for BK viremia and BK virus nephropathy. Results: Among the 626 kidney transplant recipients, 38 cases (6.1%) of BK viremia and 18 cases (2.9%) of BK virus nephropathy were diagnosed. Univariate analysis revealed that UIBC, TIBC, and TSAT were associated with the occurrence of BK viremia and BKPyVAN. In the training cohort, multivariate analysis showed that preoperative TSAT was an independent risk factor for BK viremia (1.03 [1.01-1.05], P=0.009) and BK virus nephropathy (1.05 [1.01-1.09], P=0.011). The C-index for the nomogram model predicting BK viremia and BK virus nephropathy after kidney transplantation was 0.77 and 0.82 in the training cohort, and 0.88 and 0.92 in the validation cohort, respectively. Conclusions: Preoperative transferrin saturation levels in kidney transplant recipients are closely associated with the reactivation and progression of BK virus after transplantation.