10 mL (5 mL min.) aliquot of 24 hour Urine. Collect urine with 25 mL 50% concentrated HCl to maintain pH below 3. For children adjust the volume of acid according to the expected urinary output. Keep urine refrigerated during collection. Mix well before aliquoting. Record body weight ; 24 hour urine volume on container and test request form. Ship refrigerated or frozen. Avoid vitamin C and citrus fruits 48 hours prior to specimen collection.
Sample Wed Sat by 9 am; Report Same day
This assay is useful for monitoring therapy for kidney stones and identifying increased urinary oxalate as a risk factor for stone formation. It also helps in the diagnosis of Primary or Secondary hyperoxaluria. Ingestion of Ascorbic acid may falsely elevate urinary oxalate excretion.
Avoid vitamin C and citrus fruits 48 hours prior to specimen collection.