Is it time to revisit residual renal function in haemodialysis? (Review Article)

Abstract

SUMMARY:Residual renal function (RRF) is not currently emphasized for patients undergoing haemodialysis (HD). The role of RRF is well recognized in the peritoneal dialysis population as studies have clearly demonstrated a survival benefit with preservation of RRF. There is however, data to suggest that RRF is important in HD patients as well. Contemporary HD therapies using high flux biocompatible synthetic dialysers, bicarbonate buffered ultrapure dialysis fluids with ultrafiltration control appear to allow better preservation of RRF. The long held belief that peritoneal dialysis is better at preserving RRF than HD may no longer be true. More robust studies are required to determine the relative importance of RRF in HD and strategies to best preserve this vital asset.KEY WORDS: dialysis adequacy, haemodialysis, peritoneal dialysis, residual renal function.The importance of residual renal function (RRF) in dialysis patients has begun to re-emerge over the last few years, as outcome studies in peritoneal dialysis (PD) patients have clearly demonstrated a significant survival benefit with preservation of RRF. However, most nephrologists do not appear to place the same emphasis on monitoring and preservation of RRF in haemodialysis (HD) patients.The role of RRF in HD patients is often neglected as there is a common notion that RRF is lost rapidly after initiation of haemodialysis and hence inconsequential in terms of patient outcome. There has also been the concern that PD is minimally adequate; thus, RRF may play a more essential role in PD rather than in HD where it was thought that the loss of RRF can be compensated by the concomitant increase in small solute clearance provided by HD therapies. It does not help that the measurement of RRF in HD is more complicated than that in PD, as HD patients are not in a steady state because of the intermittent nature of the dialysis therapies. WHY IS RRF IMPORTANT IN DIALYSIS?Residual renal function is a significant determinant of morbidity and mortality in dialysis patients. Several studies have reported that RRF, but not the dose of PD predicted mortality.1-4 The original CANUSA study where total (peritoneal and renal) small solute clearance significantly predicted mortality, resulted in the assumption that peritoneal small solute clearance must be important.5 However, a re-analysis of the CANUSA data by Bargman et al. showed that the predictive power of lower mortality lay exclusively in the RRF, and not in the small solute clearance component. 6 Each increment of 5 L/week per 1.73 m 2 in residual kidney glomerular filtration rate (GFR) was associated with a 12% reduction in the relative risk (RR) of death while there was no association with peritoneal creatinine clearance. Every 250 mL of daily urine output conferred a 36% reduction in mortality. What is not commonly recognized in the nephrology community is that there were data to suggest that RRF is important in the HD population as well. EVIDENCE FOR THE BENEFIT OF RRF IN HD PATIENTSShemin et al. reported that the pr...

Contribution of Residual Function to Removal of Protein-Bound Solutes in Hemodialysis

“…The presence of residual native kidney function is associated with improved survival in dialysis patients (1)(2)(3)(4)(5)(6). Residual function is also associated with better nutrition, less evidence of inflammation, less cardiac hypertrophy, and better quality of life (5)(6)(7)(8)(9)(10).…”

Incremental and twice weekly haemodialysis in Australia and New Zealand

“…Preservation of residual kidney function is well recognised as a major goal in PD but is in most places not a major focus of HD practice. There is however a growing recognition of the importance of residual kidney function to outcomes in HD, and a movement to place more emphasis on this in dialysis practice . Fluid control, need for erythropoiesis‐stimulating agents and middle molecule clearance are all factors dependent in large part on residual kidney function .…”

Nephrogenic systemic fibrosis versus contrast‐induced nephropathy: Risks and benefits of contrast‐enhanced MR and CT in renally impaired patients

“…For patients on dialysis it has been shown that there is benefit from preservation of even minimal residual renal function, and that ICAs may further diminish renal function in these patients. The authors recommend that ICAs should be contraindicated in these patients (46,47). Current data suggest that use of GBCAs selected for low risk of NSF have an associated NSF incidence that remains too small to measure, even in patients with severe renal disease.…”