Xylitol infusion and oxalate formation in rabbits

Oxalate levels in the plasma and urine fractions of fasted normal, oxythiamin treated (20 mg/kg) and 4-deoxypyridoxine treated (300 mg/kg) rabbits were determined following infusion with either xylitol or glucose at a dose of 2 g/kg body weight. Biochemical determinations showed that transient thiamin or pyridoxine deficient states had been induced in the antivitamin treated rabbits. In the first 24 hour following infusion with either carbohydrate, urinary oxalate levels remained within the normal range for all groups. Oxythiamin hastened the appearance of the transient, elevation in plasma oxalate concentrations seen in rabbits after infusion with glucose. After xylitol infusion, the elevation of plasma oxalate was not significnatly above normal. 4-Deoxypyridoxine enhanced peak plasma oxalate levels above those of controls for both sugars. Glucose, at an equivalent dose to xylitol, resulted in higher plasma oxalate levels than xylitol for all groups. Infusions of [U-14C]xylitol and [U-14C]glucose solutions into 4-deoxypyridoxine treated rabbits demonstrated a conversion of the administered radioactive carbon into 14C oxalate of 0.01% with a high dilution of the specific activity. The results suggest that oxalate production from xylitol is negligible; any toxicity related to xylitol administration is not a consequence of oxalate production.