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

Background. Dialysis patients with primary hyperoxaluria are exposed to risks and hazards associated with calcium oxalate salt deposition in body tissues, since regular dialysis treatment does not adequately correct hyperoxalaemia. The purpose of this study was to evaluate oxalate mass removal using various dialysis modes in a patient suffering from primary hyperoxaluria type 1 (PHI). 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 All dialysis sessions lasted for 4 h. Blood was withdrawn and spent dialysate was collected in plastic bags every hour to evaluate mass removal. Oxalate concentration in plasma and in spent dialysate was determined by an enzymatic method. Oxalate generation, distribution volume and tissue deposition were calculated using single-pool models adapted from previous studies. Results. Although no significant difference was found in mass removal per session 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 weekly oxalate removal, all three types of renal replacement therapy were insufficient to compensate for estimated oxalate generation. To eliminate sufficient amounts of oxalate generated in PHI patients, at least 8 h of daily dialysis with a high-flux membrane would probably be required. Renal replacement therapy for PH 1 patients needs be improved further.