Oxalate removal by daily dialysis in a patient with primary hyperoxaluria type 1

Background. Dialysis patients with primary hyperoxaluria are exposed to ris ks and hazards associated with calcium oxalate salt deposition in body tiss ues, since regular dialysis treatment does not adequately correct hyperoxal aemia. The purpose of this study was to evaluate oxalate mass removal using various dialysis modes in a patient suffering from primary hyperoxaluria t ype 1 (PH1). Methods. Oxalate kinetics during daily haemodialysis was compared with that of standard haemodialysis (STD HD) and haemodiafiltration (HDF) using high flux dialysers (FB 170 H and FB 210 U. Transdial. Paris. France). All dial ysis sessions lasted for 4 h. Blood was withdrawn and spent dialysate was c ollected in plastic bags every hour to evaluate mass removal. Oxalate conce ntration in plasma and in spent dialysate was determined by an enzymatic me thod. Oxalate generation, distribution volume and tissue deposition were ca lculated using single-pool models adapted from previous studies. Results. Although no significant difference was found in mass removal per s ession between dialysis strategies and dialyser types, weekly mass removal with daily HD was about 2 times greater than with STD HD or HDF. Even when daily HD was performed. the oxalate generation rate-mass removal ratio (G/R ratio) remained at a value of approximately 2. Conclusion. Although daily HD sessions led to a substantial increase in wee kly oxalate removal, all three types of renal replacement therapy were insu fficient to compensate for estimated oxalate generation. To eliminate suffi cient amounts of oxalate generated in PH1 patients, at least 8 h of daily d ialysis with a high-flux membrane would probably be required. Renal replace ment therapy for PHI patients needs be improved further.