#885 Combination of medium cut-off dialyzer membrane and diet modification to reduce serum concentrations of p-cresyl sulfate and indoxyl sulfate

Abstract

Abstract Background and Aims Online hemodiafiltration (ol-HDF) may be considered currently as the best choice for chronic hemodialysis (HD) treatment, but medium cut-off (MCO) membranes may provide similar efficiency for larger and protein-bound toxin removal. P-cresyl sulfate (PCS) and indoxyl-sulfate (IS) concentration depends mainly on residual renal function and diet. Increased dietary fiber intake and short-chain fatty acid (SCFA) supplementation were associated with decreased production of PCS and IS. The aim of this study was to pragmatically combine MCO use with diet modification in an attempt to reduce serum concentration of PCS and IS and compare this strategy to online HDF use. Method We report preliminary results from a subset of a study sample with 42 chronic prevalent HD patients in a prospective randomized controlled interventional study. Two weeks after standard bicarbonate HD (BHD), patients were randomized to hemodialysis with MCO membrane (EXP group) or ol-HDF with a standard "high-flux" (HF) dialyzer membrane (CON group). After 4 weeks, both groups were supplemented by a change in the diet with increase of the daily intake of dietary fiber to 30g and addition of a SCFA propionate in the dose of 1g daily for 8 weeks. Two main outcomes were serum concentrations of PCS and IS. Measurements were taken at baseline (after 2 week wash-in period), after 4 weeks of the first intervention phase (MCO vs. ol-HDF; T1), after 8 weeks of the second intervention phase (fiber and SCFA supplementation; T2) and finally, after 4 weeks of wash-out period with BHD (T3). Results From 42 participants, 38 completed the study (63.2% men, 66.4±10.9 years, Charlson comorbidity index 5.7±2.3). In the CON group, serum concentrations of PCS (in μg/ml) were 36.8±19.6 (baseline), 36.9±20.8 (T1), 32.4±17.4 (T2) and 38.6±22.1 (T3). Serum concentrations of IS (in μg/ml) were 31.8±13.0 (baseline), 32.9±14.7 (T1), 29.5±9.1 (T2) and 35.5±16.8 (T3). In the EXP group, serum concentrations of PCS were 33.5± 16.6 (baseline), 35.9±17.8 (T1), 34.0±16.1 (T2) and 37.4±21.5 (T3). Serum concentrations for IS were 39.6±12.6 (baseline), 37.3±12.9 (T1), 42.3±13.5 (T2) and 41.0±12.8 (T3). Repeated measures ANOVA revealed no significant time*group interaction for PCS (F(1,33)=0.479, p=0.698, ŋ2=0.014) and IS (F(1,33)=2.392, p=0.073, ŋ2=0.068). There was a significant within-group increase in serum IS concentration between T2 and T3 in CON group (p=0.042). There was a trend towards a decrease in PCS concentration between T1 and T2 and increase between T2 and T3 in CON group. Conclusion The results of the study suggest both hemodialysis methods are equivalent in eliminating PCS and IS. Additional fiber and SCFA propionate supplementation did not decrease serum PCS and IS concentrations significantly, although there was a trend towards lower serums concentration of PCS after diet modification in CON group.