Calcium, 24 Hour Urine Without Creatinine : 11313

24CARR or 11313

Refrigerate during and after collection. Collect urine with 25 mL of 6N HCl to maintain a pH <3. Do not include first morning specimen; collect all subsequent voidings. The last specimen collected should be the first morning specimen voided the following morning at the same time as the previous morning's first voiding.

Specify 24-hour total volume and collection duration on specimen container and test requisition.

Preferred Specimen
10 mL aliquot of a well-mixed, 24-hour collection

Alternative Specimens
Unpreserved urine; Urinalysis transport tube (yellow-top, blue fill line, preservative tube)

Minimum Volume
2 mL

Room temperature.

Room temperature: 5 days; Refrigerated: 35 days; Frozen: 6 months

Sunday - Saturday

1 day

Urinary calcium reflects dietary intake, rate of calcium absorption by the intestine and bone resorption. Urinary calcium is used primarily to evaluate parathyroid function and the effects of vitamin D. A significant number of patients with primary hyperparathyroidism will have elevated urinary calcium. However, there are other clinical entities that may be associated with increased urine calcium: Sarcoidosis, Paget's disease of bone, vitamin D intoxication, hyperthyroidism and glucocorticoid excess. Decreased urine calcium is seen with thiazide diuretics, vitamin D deficiency and familial hypocalciuric hypercalcemia.