Not Residual Kidney Removal but Peritoneal Clearance Dominates in Uric Acid Control in Peritoneal Dialysis

Background: There’s a paucity of systematic study focusing on clearance of uric acid (UA) in peritoneal dialysis (PD). The aim of this study was to investigate peritoneal UA removal and its influencing factors in PD patients. Methods: This was a cross-sectional study. Patients who performed peritoneal equilibration test (PET) and Kt/V from April 1, 2018 to August 31, 2019 were enrolled. The demographic data, clinical and laboratory parameters including the UA levels in the dialysate, blood and urine samples were collected. Results: Finally, there were 180 prevalent PD patients (52.8% male). Compared with normal serum UA (SUA) group, the hyperuricemia group showed significantly lower peritoneal UA clearance (39.1±6.2 vs. 42.0±8.0 L/week/1.73m2, P=0.008). Peritoneal UA clearance but not residual kidney removal was revealed to be independently associated with continuous [standardized coefficients (β) -0.21, 95% confidence interval (CI) -0.07, -0.006] and categorical SUA level [odds ratio (OR) 0.91, 95% CI 0.84,0.98]. Furthermore, the higher (high or high-average) transporters showed greater peritoneal UA clearance than the lower (low or low-average) transporters (42.0±7.0 vs. 36.4±5.6 L/week/1.73 m2, P<0.001). Among the widely used solute removal indicators, peritoneal creatinine clearance (CCL) performed best to predict higher peritoneal UA clearance in ROC analysis [area under curve (AUC) 0.96, 95% CI 0.93-0.99]. In multiple linear regression, lower albumin level (β -0.06, 95%CI -2.09, -0.19), higher transporters (β 0.06, 95%CI 0.05, 1.69) and greater peritoneal CCL (β 0.95, 95%CI 0.81, 0.93) were independently associated with higher peritoneal UA clearance. Conclusions: It was peritoneal removal but not residual kidney function that dominated in SUA balance of PD patients. Albumin level, peritoneal transport type and peritoneal CCL were identified as independent determinants of peritoneal UA clearance.