Role of the dialyzer membrane on the overall phosphate kinetics during hemodialysis.

Background/aim: We investigated the potential role of the membrane type on phosphate kinetics.

Methods: Six patients on dialysis (HD) were studied using modified cellulose (Hemophan), ethylene-vinyl alcohol (EVAL) and polyacrylonitrile (PAN). Total (TPR), extracellular (EPR) and intracellular (IPR) phosphate removal and effective dialyzer phosphate clearance (K(d)) were determined by the DDQ method. The intercompartment transfer coefficient (K(C)) was calculated using a mathematical model. Erythrocyte phosphate (P(ERY)) and 2,3-biphosphoglycerate (2,3-BPG) concentrations were determined before and after HD.

Results: TPR was 1.2+/-0.4, 1.10+/-0.4 and 1.09+/-0.4 g with Hemophan, EVAL and PAN, respectively (p=n.s.). EPR and IPR were independent of membrane type. There was no difference in K(C) between membranes (321+/-70, 338+/-92 and 341+/-83 ml/min, respectively). The P(ERY) and 2,3--BPG remained statistically insignificant for all membranes.

Conclusion: Our results show that the type of membrane does not influence the kinetics of phosphate during dialysis, neither in the transfer from plasma to dialysate nor from the intra- to the extracellular compartment.