Residual renal function and post dialysis urea rebound

Kt/v is used to estimate haemodialysis prescription and treatment adequacy and usually does not include evaluation of urea rebound. In addition urea clearance provided by the presence of residual renal function (RRF) is additive to dialytic urea clearance. Rebound is a phenomenon involving other molecules such as creatinine and phosphorus. The aim of this study was to investigate the role of RRF on post dialysis urea, creatinine and phosphorus rebounds. We investigated 7 patients with RRF (group 1) and 7 uraemic anuric patients (group 2). Urea rebound was lower in group 1 than group 2: 9.5 +/- 4% vs 18 +/- 7% (p = 0.04). Creatinine rebound and phosphorus rebound were similar in both groups 15.2 +/- 9% group 1 vs 14.6 +/- 5% group 2 (p = NS) and 16.7 +/- 7% group 1 vs 20 +/- 7% group 2 (p = NS) respectively. Our data suggest Kt/v calculated without considering rebound overestimates haemodialysis efficacy.