Lower Selenoprotein P Is Independently Associated with Peripheral Arterial Disease in Peritoneal Dialysis

Background/Objectives: Peripheral arterial disease (PAD) is a common yet often unrecognized complication in patients receiving peritoneal dialysis (PD). Considering that ankle–brachial index (ABI) can be difficult to interpret in this population, additional vascular biomarkers are needed. Selenoprotein P (SePP) is a major selenium transport protein with antioxidant and metabolic regulatory functions and may reflect vascular stress relevant to PAD. We investigated the association of circulating SePP levels with ABI-defined PAD in patients on PD. Methods: In this cross-sectional analysis of 98 patients on PD, ABI was assessed using an automated oscillometric device, and ABI < 0.9 was defined as ABI-defined PAD. Serum SePP levels were measured using enzyme-linked immunosorbent assay. Results: ABI-defined PAD was identified in 20 patients (20.4%). Compared with patients with normal ABI, those with ABI-defined PAD were older (p = 0.014) and had significantly higher prevalence of diabetes mellitus (p = 0.033), longer PD vintage (p = 0.036), higher fasting glucose (p = 0.005) and C-reactive protein (p = 0.003) levels, and lower SePP concentrations (p < 0.001). Low SePP level remained independently associated with ABI-defined PAD after multivariate adjustment (odds ratio 0.930, 95% confidence interval 0.771–0.997; p = 0.032) and consistently across reinforced bootstrap resampling. SePP correlated positively with ABI on the left (p = 0.001) and right (p = 0.002) sides. Conclusions: Among patients undergoing PD, a low serum SePP level was independently associated with ABI-defined PAD and positively associated with ABI, suggesting that SePP may serve as an associative biomarker reflecting vascular vulnerability rather than a diagnostic indicator in this population.