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Calcium, 24 Hour Urine
MessageTest performed at York Hospital Laboratory.
Test Code
UCAL24
CPT Codes
82340
Preferred Specimen
20 mL aliquot of a well mixed 24-hour urine, submitted in a plastic leakproof container
Instructions
York Back Lab: After urine collection, add 6N HCl to a well mixed aliquot of 24 hour urine to maintain a pH of 1.5 - 5.0.
Transport Temperature
Refrigerated
Specimen Stability
Room temperature: 5 days Refrigerated: 5 weeks Frozen: 6 months
Methodology
Colorimetric
Setup Schedule
Daily
Report Available
Next day
Reference Range
Dietary Calcium Intake
Ca-free | 5-40 mg/day |
Low to average | 50-150 mg/day |
Average | 100-300 mg/day |
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.