Includes Creatinine, 24 Hour Urine
Preferred Specimen(s): 10 ml aliquot of a 24-hour collection. Collect urine with 25 mL 6N HCl.
Instructions Refrigerate during and after collection. Do not include first morning specimen; collect all subsequent voiding. The last sample collected should be the first morning specimen voided the following morning at the same time as the previous morning’s first voiding. Record 24-hour urine volume on test request form and urine vial.
Transport Container 24-hour urine container
Transport Temperature
- Refrigerated preferred;
- Room temperature acceptable;
- Frozen acceptable
Reject Criteria: None
Methodology: Spectrophotometry
Clinical Significance 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.