Objective: To compare β2-microglobulin (β2M) clearance between on-line hemodiafiltration (HDF) and high flux demodialysis (HFHD).
Material and Method: The total, convection/diffusion, and membrane adsorption components of β2M clearance in 10 hemodialysis patients treated with on-line HDF, at the replacement fluid rates of 75 (HDF75) and 125 (HDF125) mL/min, were determined and compared with HFHD.
Results: The total β2M clearance in the HDF 125 group was significantly higher than the HDF75 group (124.5 + 4.4 vs 101.3+4.1 mL/min; p < 0.05); both values were much greater than the HFHD group (p < 0.01). The convection/diffusion was the major portion of total β2M clearance in all three groups. The values of convection/diffusion and membrane adsorption in both HDF groups were about 2 and 3 times, respectively, of the HFHD group (p < 0.01). Both components of β2M clearance in the HDF125 group did not statistically differ from the HDF75 group, however; the value of convection/diffusion clearance in HDF125 was more than in the HDF75 group. Regarding Kt/Vurea and phosphate clearance, there were no significant differences among the study groups.
Conclusion: On-line HDF could provide more β2M clearance than HFHD by increasing both the convection/diffusion, and membrane adsorption clearances. HDF125 provided more total β2M clearance than HDF75 from the convection/diffusion mechanism while the adsorptive mechanisms were equal.

Keywords: Hemodiafiltration, High flux hemodialysis, β2-microglobulin, Convection/diffusion, Membrane adsorption