Original Article Oxalate clearance by haemodialysis—a comparison of seven dialysers

Background. In patients with primary hyperoxaluria (PH) and oliguric end-stage renal disease, oxalate removal is largely dependent on the clearance by dial-ysis. Data on the oxalate clearance of newer dialyser types are scarce or absent. Therefore, we measured oxalate clearances of seven dialysers in a single 52-year-old female patient with PH. Since haemodiafiltration (HDF) has been advocated to increase oxalate clearance, we also assessed the effect of different pre-dilution flows. The goal of the study was to select the dialyser and pre-dilution flow combination with the highest oxalate clearance. Methods. Oxalate clearances were assessed by simul-taneously taking afferent blood and efferent dialysate samples at 30, 60, 120 and 180min after the start of haemodialysis. Blood flow and dialysate flow were 350 and 500ml/min, respectively. All dialysers were tested at a pre-dilution flow of 2 l/h. Six dialysers were also tested at either a pre-dilution flow of 4.5 l/h or without HDF, depending on the ultrafiltration coefficient of the dialyser. Results. Oxalate clearances differed markedly between the tested dialysers, ranging from 144±10 to 220±12ml/min. The highest oxalate clearances were achieved with HdF100S (219±10ml/min) and Sureflux FB-210U (220±12ml/min) at a pre-dilution flow of 2 l/h. Higher pre-dilution flows (2 l/h vs no HDF or 4.5 vs 2.0 l/h) yielded similar oxalate clearances. Conclusion. The highest oxalate clearances were achieved with a high-flux polysulfone and a cellulose triacetate dialyser with a large surface area. Higher pre-dilution flows did not augment oxalate clearance