Efficiency of three different hemodialysis membranes for plasma porphyrin removal

To assess the capability of three different membranes to remove porphyrins, plasma and dialysate porphyrin levels were fluorometrically measured in 10 patients with end-stage renal failure who were on hemodialysis. Three different hemodialysis membranes were used: cuprophan, polyacrylonitrile, and cellulose triacetate. Total plasma porphyrin concentrations decreased after dialysis, but to a lesser extent when using the cuprophan membrane (19%) than with the polyacrylonitrile (26%) or cellulose triacetate (30%) membranes (P < 0.01). However, since the free plasma porphyrin fraction remained unchanged, it can be assumed that the equilibrium between protein-bound and non-protein-bound (free) porphyrins is displaced toward the latter fraction. Dialysate porphyrin levels were lower (P < 0.01) when using the cuprophan membrane (10.1 micrograms/session) than when using polyacrylonitrile (17.8 micrograms/session) and cellulose triacetate (21.9 micrograms/session). Although most of the plasma porphyrins are protein bound, our results show that hemodialysis can remove significant amounts of non-protein-bound (free) porphyrins. The polyacrylonitrile and cellulose triacetate membranes had a greater capacity for porphyrin removal than cuprophan. Thus, two high-permeability membranes (polyacrylonitrile and cellulose triacetate) should be used whenever a reduction of plasma porphyrin levels is desired.