Calcium, 24 Hr Urine
Fasting Required: No

Specimen: Urine, 24 hour

Collection Instructions: 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.

Results: 5-7 Business days

Description: 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. High levels of urine calcium may be due to chronic kidney disease, high vitamin D levels, leaking of calcium from the kidneys into the urine - which causes calcium kidney stones, sarcoidosis, taking too much calcium, hyperparathyroidism, or use of diuretics ("water pills"). Low levels of urine calcium may be due to malabsorption disorders, kidney disorders, hypoparathyroidism, Use of a water pill called a thiazide diuretic, or very low levels of vitamin D.

Methodology: Spectrophotometry (SP)

Limitations: Oral contraceptive use may depress results. Requires accurate 24-hour urine collection.

Note: Result turnaround times are an estimate and are not guaranteed. Our reference lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.