Impact of citrate dialysate on middle molecular weight uremic toxin adsorption and removal in high-flux and MCO dialysis membranes

Hemodialysis treatment with bicarbonate requires a weak acid to prevent salt precipitation. Acetate is implemented in chronic hemodialysis while citrate is used in continuous treatments due to its anticoagulation properties, offering a plethora of clinical benefits and reduces protein adsorption to polysulfone membranes. The outcomes of citrate in the adsorption properties of hemodialyzers, especially on medium cut-off hemodialyzers are unknown. To check 21 chronic hemodialysis patients underwent their mid-weekly treatment using a FX CorDiax 80, Solacea-19 H or a Theranova 400 hemodialyzer combined with acetate or citrate-based dialysate. Pre and post-treatment blood samples were taken to calculate the reduction ratio of several uremic surrogates and proteins. An elution protocol was performed to every hemodialyzer to assess adsorption. Significant removal differences among membranes were found for β2-microglobulin, TNF-α, κ and λ free light chains, as hemodiafiltration and expanded hemodialysis were compared regarding the acidifier. Citrate significantly (p = 0.011) improved removal for κ free light chains (for Theranova 400) whilst all other solutes showed no significant different depuration between acidifiers. For each membrane type analyzed, no statistical differences in adsorption were found between concentrates on the same membrane. Implementing the citrate-based concentrate does not modify removal and adsorption properties of high-flux and medium cut-off membranes. The clinical benefit shown in other studies of using citrate instead of acetate could not be explained because of this mechanism.