Evolution of the single-pool urea kinetic model

Our interest in urea kinetic modeling (UKM) was stimulated some 30 years ag o at the time of the advent of hollow fiber kidneys with greatly improved u rea transport. This led to examination of the interaction between time and clearance in computing the dialysis dose. In early studies a fixed-volume s ingle-pool UKM was used but this frequently gave spurious high volumes and led to the advent of the variable-volume single-pool model. The role of vol ume calculation in assessment of the delivered dialysis dose and the value of normalized protein catabolic rate (nPCR) calculation are reviewed. More recently quantification of double-pool effects has become simplified and no w is widely used for UKM. The National Cooperative Dialysis Study (NCDS) re sulted in the concept of dose quantification by Kt/V. This is reviewed, inc luding the controversy surrounding interpretation of the NCDS. Currently th ere is great interest in more frequent dialysis, 4-6 days/week. The develop ment of a new dose parameter, the standard Kt/V(stdKt/V), to enable quantit ative comparison of dose with widely varying dose schedules is discussed.