[Dialysis adequacy and Kt/V]

Fractional clearance of urea to quantify the adequacy of dialysis was introduced in the late 1980s to allow nephrologists to personalize hemodialysis treatment, assess its effectiveness (dose), and create an index that would represent the concept of adequate dialysis. Since then, the number of nephrologists really involved in this novelty has been rather small, while the majority have been using the new instrument more or less uncritically. At the same time, the dialysis technology has evolved: the extracorporeal techniques have become more diversified, dialyzers have been transformed in terms of materials, hydraulic permeability and purification efficiency, and treatment schedules have been modified in terms of duration and frequency. The purpose of this paper is to evaluate, at a distance of about 30 years, the validity of the control parameter of dialysis - Kt/V - in 2010. In essence, the authors claim that Kt/V is of marginal utility in the quantification of traditional dialysis, while it is wholly inappropriate for frequent or long-term treatment schemes. We maintain that the calculation of Kt/V is still a tool to be used - also recommended by international guidelines - at least until the validation of new and more efficacious solutions, in order to avoid ineffective dialysis sessions (in terms of dose for small molecules), although it does not provide any certainty of a fully adequate performance in terms of reduced morbidity and mortality.