Peritoneal sodium removal compared to glucose absorption in peritoneal dialysis patients treated by continuous ambulatory peritoneal dialysis and automated peritoneal dialysis with and without a daytime exchange.

Sodium removal in peritoneal dialysis (PD) depends on convective clearance, typically generated by a glucose gradient, but this can result in glucose absorption. We wished to determine which factors determine peritoneal sodium losses to glucose absorption (PD Na/Gluc). Peritoneal sodium losses and glucose absorption were calculated from measured 24-h collections of PD effluent, in patients attending for assessment of peritoneal membrane function. Five hundred and fifty eight patients; 317 (56.8%) males, mean age 56.1 ± 16.0 years, were studied, 281 treated by automated peritoneal dialysis (APD) with a daytime exchange (50.4%); 179 (32.1%) by APD and 98 (17.6%) by continuous ambulatory peritoneal dialysis (CAPD). All patients used glucose containing dialysates, with 352 (63.1%) using icodextrin and 210 (37.6%) hypertonic (22.7 g/L glucose) dialysates. The ratio of PD Na/Gluc was 0.14 (0.02-0.29). Patients using icodextrin had a higher ratio (0.16 (0.03-0.32) versus 0.11 (-0.02-0.26), P < .001), as did those using 22.7 g/L glucose versus 13.6 g/L (0.16 (0.06-0.32) versus 0.13 (-0.01-0.19), P < .01), and CAPD versus APD (0.18 (0.05-0.36) versus 0.11 (0.0-0.27), P < .05), respectively. A multivariable model showed that 24-h ultrafiltration (odds ratio [OR] 7.6 (95% confidence interval [3.9-14.8]), P < .001 was associated with increased PD Na/Gluc, whereas APD (OR 0.19 (0.06-0.62), P < .01 and increased extracellular water to total body water (OR 0.001 [0-0.08], P = .03) were associated with lower ratios. Twenty four-hour peritoneal ultrafiltration was strongly associated with PD Na/Gluc, whereas patients treated with APD cyclers without a daytime icodextrin exchange and those with an increased extracellular water to total body water had lower peritoneal sodium losses but with greater peritoneal glucose absorption.