Urea rebound and residual renal function in the calculation of Kt/V and protein catabolic rate

Kt/V-urea and protein catabolic rate (PCR) are used for dialysis prescription and evaluation of protein intake of patients on regular dialysis treatment. The study was undertaken to determine the implication of urea rebound and residual renal function (RRF) on the calculation of Kt/V-urea and PCR for 61 patients. Kt/V-urea and PCR were calculated, implementing or not urea rebound at one hour after the end of dialysis session. Urea and creatinine rebound rate in patients without RRF was significantly higher than in patients with RRF (P < 0.05). In patients without RRF, creatinine generation rate and Kt/V-urea calculated without rebound were significantly higher than calculated with rebound (P < 0.001). On the contrary, calculation of urea generation and PCR is not affected by these parameters. It is concluded that: (1) Rebound rate magnitude of urea and creatinine is dependent on solute molecular weight, RRF and probably on dialysis duration, whereas rebound rate magnitude of phosphorus is not affected, and (2) Rebound should be taken into account in the calculation of Kt/V-urea and creatinine generation rate in patients without RRF, otherwise, they would be overestimated.