Benefits of first-half intensive haemodiafiltration for the removal of uraemic solutes.

Aim: Haemodiafiltration (HDF) is the most efficient blood purification method and can remove a wide spectrum of solutes of different molecular weights (MW). The purpose of this study was to investigate whether the removed amounts of solutes, especially the larger molecules, could be increased by changing the HDF filtration procedure. Methods: A new first-half intensive HDF treatment (F-HDF) was designed, whereby convective clearance is intensively forced during the first half of a HDF session. We compared the removed amounts of solutes in the same group of nine patients treated by F-HDF, constant rate-replacing HDF (C-HDF) and a high-flux haemodialysis (HD). Results: F-HDF can remove significantly larger amounts of alpha(1)-microglobulin (MG), molecular weight (MW) 33 000, compared with HD and C-HDF (30.1 +/- 15.1 vs 12.4 +/- 0.3, 15.0 +/- 3.1 mg, P < 0.01). Regarding the removal amounts and clear space of beta(2)MG, MW 11 800, there were no significant differences between the three treatment modalities. Regarding amounts of creatinine, urea nitrogen and phosphorus, there were no significant differences between the three treatment modalities. Conclusion: In post-replacement HDF with a high-flux membrane dialyzer, the method used in the present study in which replacement is completed during the first half of the process, is associated with a greater rate of larger molecule removal than the conventional uniform replacement method.