Residual Kidney Function and the Impact of Dialysis Modality

Residual kidney function (RKF) plays a crucial role in improving outcomes for dialysis patients. Enhanced middle molecular clearance has been proposed as one of the several benefits of preserved RKF. Most patients who start dialysis retain some residual kidney function, providing a rationale for using incremental dialysis. RKF has been associated with mortality benefit in both peritoneal dialysis (PD) and hemodialysis (HD). It also influences technique longevity and lowers peritonitis rates in patients on PD. In both dialysis modalities, RKF improves volume management and blood pressure control. Additional potential benefits include reduced dietary restrictions, improved nutritional status, better quality of life (QOL), reduced erythropoiesis-stimulating agent (ESA) requirements, lower inflammatory marker levels, and improved bone health. RKF is less frequently measured in HD patients primarily due to the lack of standardized methods and logistical challenges. Several equations for estimating RKF have been proposed, but none are widely adopted in clinical use. Historically, HD was believed to cause a rapid loss of RKF; however, more recent data have challenged this view. Future research should focus on identifying factors that affect RKF, standardizing measurement methods, and developing strategies for preservation. Efforts to preserve RKF should be made for all dialysis patients, regardless of modality.