Increased dialysate levels of phospholipids containing unsaturated fatty acid are associated with increased peritoneal transport rate

BACKGROUND High peritoneal transport status in end-stage renal disease patients receiving peritoneal dialysis was shown to be associated with increased morbidity and mortality. Although the pathogenesis of increased peritoneal transport is still not clear, previous studies have demonstrated that phospholipids (PLs) are present on the peritoneal mesothelium and when added to dialysate can decrease the peritoneal fluid absorption rate and increase peritoneal fluid removal. In the present report, we explored the relationship between peritoneal transport and dialysate loss of endogenous PLs. METHODS We evaluated 48 prevalent continuous ambulatory peritoneal dialysis patients with high or low peritoneal transport in a cross-sectional study. The 4-hour dwell dialysate PL profile was analyzed by high-performance liquid chromatography coupled with electrospray ionization ion trap mass spectrometry. The patients' peritoneal small solute transport rate was assessed by D/P(Cr) at 4 h and their fluid transport by kinetic modeling. RESULTS While there were no significant differences between the 2 groups in age, sex, diabetic status and time on dialysis, high transporters had a significantly higher D/P(Cr) and peritoneal fluid absorption rate (K(e)) than low transporters. The PLs in dialysate effluents mainly consisted of PLs containing unsaturated fatty acid, and the concentrations, as well as the amount, of PLs were significantly elevated in the dialysate of high transporters as compared to low transporters. CONCLUSION Our results showed that dialysate from high transporters exhibited elevated levels of PLs, especially PLs containing unsaturated fatty acid, suggesting a possible loss of peritoneal surface-active PLs in peritoneal dialysis, and this loss may contribute to the alteration in peritoneal transport.