10 mL (5 mL min.) aliquot of 24-hour Urine. Collect urine with 25 mL 50% concentrated HCl to maintain pH below 3. Record 24-hour urine volume on test request form and urine vial. Ship refrigerated or frozen.
Sample Daily by 4 pm; Report Same day
Citrate binds to calcium and inhibits kidney stone formation. Thus low levels of citrate may lead to kidney stones and is the most important risk factor of kidney stone formation in children. The treatment includes increasing urinary citrate excretion.