Association of Serum P-Cresyl Sulfate Level with Peripheral Artery Disease in Kidney Transplantation Patients

Background: p-Cresyl sulfate (PCS) has been linked to vascular dysfunction through endothelial injury and vascular remodeling. Peripheral artery disease (PAD), identified by a low ankle–brachial index (ABI), is associated with increased mortality in kidney transplant (KT) recipients. This study investigated the association between serum PCS levels and PAD (as defined by ABI) in KT recipients. Methods: This cross-sectional, single-center study included 90 KT recipients. Serum total PCS levels were quantified using liquid chromatography–mass spectrometry. ABI was measured using an automated oscillometric device, and PAD was defined as ABI < 0.9. Results: Among the 90 KT recipients, 20 (22.2%) met the ABI for PAD. Patients with ABI-defined PAD had a significantly higher prevalence of diabetes mellitus (p = 0.036) and serum PCS levels (p = 0.001). Multivariate logistic regression analysis adjusting for potential confounders revealed that serum PCS levels remained independently associated with PAD (odds ratio 1.254, 95% confidence interval 1.108–1.419; p < 0.001). PCS levels were inversely correlated with both left (r = −0.339, p = 0.001) and right (r = −0.357, p < 0.001) ABIs. The association remained consistent in penalized regression models. Conclusions: Higher serum PCS levels were independently associated with ABI-defined PAD in KT recipients. The findings indicate that residual uremic toxin burden may contribute to peripheral vascular disease despite the restoration of renal function following transplantation.