Roles of peritoneal clearance and residual kidney removal in control of uric acid in patients on peritoneal dialysis

Background There have been few systematic studies regarding clearance of uric acid (UA) in patients undergoing peritoneal dialysis (PD). This study investigated peritoneal UA removal and its influencing factors in patients undergoing PD. Methods This cross-sectional study enrolled patients who underwent peritoneal equilibration test and assessment of Kt/V from April 1, 2018 to August 31, 2019. Demographic data and clinical and laboratory parameters were collected, including UA levels in dialysate, blood, and urine. Results In total, 180 prevalent patients undergoing PD (52.8% men) were included. Compared with the 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/1.73m 2 ; P = 0.008). Furthermore, higher transporters (high or high-average) exhibited greater peritoneal UA clearance, compared with lower transporters (low or low-average) (42.0 ± 7.0 vs. 36.4 ± 5.6 L/week/1.73 m 2 ; P < 0.001). Among widely used solute removal indicators, peritoneal creatinine clearance showed the best performance for prediction of higher peritoneal UA clearance in receiver operating characteristic curve analysis [area under curve (AUC) 0.96; 95% confidence interval [CI], 0.93–0.99]. Peritoneal UA clearance was independently associated with continuous SUA [standardized coefficient (β), − 0.32; 95% CI, − 6.42 to − 0.75] and hyperuricemia [odds ratio (OR), 0.86; 95% CI, 0.76–0.98] status, only in patients with lower (≤2.74 mL/min/1.73 m 2 ) measured glomerular filtration rate (mGFR). In those patients with lower mGFR, lower albumin level (β − 0.24; 95%CI − 7.26 to − 0.99), lower body mass index (β − 0.29; 95%CI − 0.98 to − 0.24), higher transporter status (β 0.24; 95%CI 0.72–5.88) and greater dialysis dose (β 0.24; 95%CI 0.26–3.12) were independently associated with continuous peritoneal UA clearance. Furthermore, each 1 kg/m 2 decrease in body mass index (OR 0.79; 95% CI 0.63–0.99), each 1 g/dL decrease in albumin level (OR 0.08; 95%CI 0.01–0.47), and each 0.1% increase in average glucose concentration in dialysate (OR 1.56; 95%CI 1.11–2.19) were associated with greater peritoneal UA clearance (> 39.8 L/week/1.73m 2 ). Conclusions For patients undergoing PD who exhibited worse residual kidney function, peritoneal clearance dominated in SUA balance. Increasing dialysis dose or average glucose concentration may aid in controlling hyperuricemia in lower transporters.