Find Locations
For hours, walk-ins and appointments.Special Instructions
The test request form must state date and time collection started and date and time collection finished. State total volume.
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
Specimen Requirements
Specimen
Urine (24-hour)
Volume
25 mL aliquot
Minimum Volume
1 mL (Note: This volume does not allow for repeat testing.)
Container
Preferred: Plastic urine container with at least 10 mL 6N HCl (hydrochloric acid). Specimens submitted without preservatives should be acidified after receipt to a pH <2.0 to dissolve calcium salts.
Collection
Instruct the patient to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Screw the lid on securely. Transport the specimen promptly to the laboratory. Container must be labeled with patient's full name, room number, date and time collection started, and date and time collection finished. pH must be <2.
Storage Instructions
Maintain specimen at room temperature.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Patient Preparation
Urinary calcium results are more meaningful if the patient has been on a low calcium, neutral ash diet for three days prior to urine collection. Drugs affecting mineral metabolism should be withdrawn, if possible, two to four weeks prior to and during collection. These include antacids, phosphates, diuretics, glucocorticoids, carbonic anhydrase inhibitors, and anticonvulsants.
Causes for Rejection
Improper labeling
Test Details
Use
Reflects intake, rates of intestinal calcium absorption, bone resorption and renal loss. Those processes relate to parathyroid hormone and vitamin D levels. Evaluation of bone disease, calcium metabolism, renal stones (nephrolithiasis);1 idiopathic hypercalciuria,2 and especially, parathyroid disorders. Follow-up of patients on calcium therapy for osteopenia.
High in 30% to 80% of instances of primary hyperparathyroidism, but urinary calcium excretion does not consistently, reliably distinguish hyperparathyroidism from other entities. High in sarcoidosis.3 Increased with immobilization, with steroid therapy, with Paget disease, and in primary (idiopathic) hypercalciuria.4 Increased with entities causing high ultrafiltrable calcium: ectopic hyperparathyroidism, some cases of renal tubular acidosis, Fanconi syndrome, increased calcium intake, vitamin D intoxication, hyperthyroidism, diabetes mellitus, acromegaly, glucocorticoid excess, some cases of Crohn's disease and ulcerative colitis, myeloma, some instances of leukemia and lymphoma, and carcinoma metastatic to bone. Reported relationship to hematuria in children.5
Low in familial hypocalciuric hypercalcemia, for which urine calcium measurements are mandatory; low with thiazide diuretics, vitamin D deficiency, renal osteodystrophy, vitamin D resistant rickets, hypoparathyroidism, pseudohypoparathyroidism and preëclampsia.6
Limitations
Decreased in patients on oral contraceptives. Lacks specificity for hyperparathyroidism when increased. Five percent of the population have hypercalciuria.4
Methodology
Colorimetric
Additional Information
The risk of forming kidney stones may be continuous rather than dichotomous and begins to increase at urinary calcium excretion >200 mg/day.7-9 Urinary calcium reflects in part the relation between GFR and tubular reabsorption.
Footnotes
1. Silverberg SJ, Shane E, Jacobs TP, et al. Nephrolithiasis and bone involvement in primary hyperparathyroidism. Am J Med. 1990 Sep;89(3):327-334.2393037
2. Lemann J Jr, Gray RW. Idiopathic hypercalciuria. J Urol. 1989 Mar;141(3 Pt 2):715-718.2645429
3. Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 50-1981. A 76-year-old woman with intermittent hypercalcemia. N Engl J Med. 1981 Dec 10;305(24):1457-1464.7300865
4. Erickson SB. Hypercalciuria. Mayo Clin Proc. 1981; 56:579.
5. Stark H, Tieder M, Eisenstein B, Davidovits M, Litwin A. Hypercalciuria as a cause of persistent or recurrent haematuria. Arch Dis Child. 1988 Mar;63(3):312-313.3355215
6. Taufield PA, Ales KL, Resnick LM, Druzin ML, Gertner JM, Laragh JH. Hypocalciuria in preeclampsia. N Engl J Med. 1987 Mar 19;316(12):715-718.3821810
7. Skolarikos A, Straub M, Knoll T, et al. Metabolic evaluation and recurrence prevention for urinary stone patients: EAU Guidelines. Eur Urol. 2015 Apr;67(4):750-763.25454613
8. Curhan GC, Willett WC, Speizer FE, Stampfer MJ. Twenty-four hour urine chemistries and the risk of kidney stones among women and men. Kidney Int. 2001 Jun;59(6):2290-2298.11380833
9. Curhan GC, Taylor EN. 24-h uric acid excretion and the risk of kidney stones. Kidney Int. 2008 Feb;73(4):489-496.18059457
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 003269 | Calcium, 24Hr Urine | 6874-2 | 013490 | Calcium, Urine | mg/dL | 18488-7 |
| 003269 | Calcium, 24Hr Urine | 6874-2 | 013243 | Calcium, Urine 24hr | mg/24 hr | 6874-2 |
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