We Use Kt/V Urea as a Measure of Adequacy of Peritoneal Dialysis

In the early days of chronic dialysis therapy, there was recognition that patients on continuous peritoneal dialysis enjoyed improvement in symptoms and signs of kidney failure similar to those receiving hemodialysis, despite slower removal rates of small solutes such as urea and creatinine. It was suggested that removal of toxic middle molecular weight solutes by the peritoneal membrane compensated for this difference. The publication of the National Cooperative Dialysis Study then focused attention on urea clearance as a significant predictor of hospitalization in hemodialysis patients. The peritoneal dialysis community made a mistake in adopting urea kinetics to the peritoneal dialysis process, while ignoring the benefits incumbent in continuous dialysis therapy and middle molecular weight solute removal. Sadly, to this day, despite the publication of many studies that have been unable to find an association between peritoneal small solute kinetics and outcome, Kt/V urea is employed as a marker of adequacy in these patients.