Determination of Kt/V and Protein Catabolic Rate Using Pre- and Postdialysis Blood Urea Nitrogen Concentrations

We developed a new urea kinetic method for simultaneous determination of the Kt/V and protein catabolic rate (PCR) only from blood urea nitrogen (BUN) concentrations before and after a single dialysis session. Using this method, the parameters were calculated within 1.5 s even when a hand-held computer with a low central processing capacity is used. The total amount of urea eliminated during three dialysis sessions in 1 week is assumed to be equal to urea volume (Gw) generated over a 1-week period (Tw): Gw = G × Tw = K T∫₀C₁dt+ T∫₀C₂dt+ T∫₀C₃dt). Here, G is the generation rate, K is the dialyzer urea clearance, T is the dialysis time and Q, C₂ and C₃ are BUN during the respective dialysis session. If this equation and the equation expressing the urea kinetics during a single dialysis session are solved together, we have a solution for Kt/V and G. The thus-obtained Kt/V and G are corrected using the change in body weight. The corrected Kt/V showed a good correspondence with the parameter calculated with the classical method, and the midweek PCR derived from G determined by the present method being equivalent to the PCR averaged for a 1-week period determined by the classical methods.