Is Expanded Hemodialysis an Option to Online Hemodiafiltration for Small- and Middle-Sized Molecules Clearance?

Background: Recent evidence suggests a better reduction rate of some uremic toxins with expanded hemodialysis (HDx). Methods: Prospective study including 8 hemodialysis patients. We divided the study in 2 phases; within the first one, we assigned 4 patients (group 1) to undergo online hemodiafiltration with a PF 210H dialyzer, and the other 4 patients (group 2) to undergo HDx with the high retention onset Theranova 500 dialyzer during 24 sessions. Later, during the second phase and after a washout period, the same patients were switched to receive HDx (group 1) and HDF (group 2). Results: No differences were found in the Urea and β2-microglobulin reduction ratio. However, in the case of myoglobin, the reduction ratio with HDF was 35 vs. 60% with HDx (p < 0.001). Similarly, in the case of prolactin, the reduction ratio with HDF was 45 and 61% with HDx (p < 0.001). Conclusions: We conclude that HDx is not inferior to online hemodiafiltration in the clearance of small and middle molecules and could be superior in the clearance of larger middle molecules.