Benefits of preserving residual renal function in peritoneal dialysis

Residual renal function (RRF) is of paramount importance in patients with end-stage renal disease, with benefits that go beyond contributing to achievement of adequacy targets. Several studies have found that RRF rather than overall adequacy (as estimated from total small solute removal rates) is an essential marker of patient and, to a lesser extent, technique survival during chronic peritoneal dialysis (PD) therapy. In addition, RRF is associated with a reduction in blood pressure and left ventricular hypertrophy, increased sodium removal and improved fluid status, lower serum β2-microglobulin, phosphate and uric acid levels, higher serum hemoglobin and bicarbonate levels, better nutritional status, a more favorable lipid profile, decreased circulating inflammatory markers, and lower risk for peritonitis in PD. As compared with conventional hemodialysis, PD is associated with a slower decrease in RRF. This highlights the usefulness of strategies oriented to preserve both RRF and the long-term viability of the peritoneal membrane. Several factors contributing to the loss of RRF have been identified and should be avoided. Renoprotective drugs and new glucose-sparing, more biocompatible PD regimes may prove useful tools to preserve RRF and peritoneal membrane function in the near future.