Ultrapure dialysate decreases plasma pentosidine, a marker of "carbonyl stress"

Background: Advanced glycation end products (AGEs) and their reactive carbonyl precursors accumulate in renal failure ("carbonyl stress"). Carbonyl stress derives from a broad derangement in the nonenzymatic biochemistry of both carbohydrates and lipids. We tested the influence of dialysate quality on plasma level of pentosidine, an AGE moiety taken as a surrogate marker of carbonyl stress, in hemodialysis patients. Methods: Plasma pentosidine is measured by means of high-performance liquid chromatography in patients hemodialyzed successively with a conventional and an ultrapure endotoxin-free dialysate. Results: Dialysate endotoxin level decreased from 0.040+/-0.017 EU/mL before the switch to the new water supply system to less than the detection limit (<0.001 EU/mL) after the switch. Plasma pentosidine levels decreased from 1.55 +/- 0.61 nmol/mL before the switch to 1.38 +/- 0.52 nmol/mL (P<0.0001) and 1.31+/-0.50 nmol/mL (P<0.0001) 3 and 6 months after the switch to an ultrapure dialysate, respectively. Decreases in plasma pentosidine levels were similar regardless of dialyzer membrane type; ie, high-flux polysulfone, high-flux polymethylmethacrylate, and low-flux cellulose acetate membranes. Unexpectedly, plasma triglyceride levels decreased from 150 +/- 116 mg/dL (1.69 +/- 1.31 mmol/L) before the switch to 124 +/- 79 mg/dL (1.40 +/- 0.89 mmol/L; P<0.01) and 119+/-75 mg/dL (1.34+/-0.85 mmol/L; P<0.01) 3 and 6 months after the switch despite unchanged total cholesterol levels, respectively. Changes in pentosidine levels were unrelated to those in triglycerides, and both were unrelated to C-reactive protein levels, which remained stable throughout the study. Conclusion: Ultrapure dialysate reduces plasma pentosidine levels and improves plasma triglyceride levels in hemodialysis patients through still undefined mechanisms.