Calcium, Random Urine with Creatinine [1633X]

Test Code

15822

CPT Codes
82310, 82570

Preferred Specimen

10 mL random urine, collected in a plastic urine container

Minimum Volume

2 mL

Other Acceptable Specimens

Unpreserved urine collected in urinalysis transport tube (yellow-top, blue fill line, preservative tube) • Preserved urine with 6N HCl acid submitted in a plastic, urine container

Instructions

Adjust pH to <2.0 with 6N HCl prior to aliquoting for calcium testing.

Transport Container

Plastic urine container

Transport Temperature

Preserved urine: Room temperature
Unpreserved urine: Refrigerated (cold packs)

Specimen Stability

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

Methodology
Spectrophotometry (SP)

Setup Schedule

Set up: Daily; Report available: 1-2 days

Reference Range

See Laboratory Report

Clinical Significance

This quantitative test, performed with a random urine specimen, may help screen for hypercalciuria, one of the established risk factors for kidney stone formation [1-3]. This test may also help assess metabolic disorders of calcium metabolism, such as hyperparathyroidism, bone disease, and idiopathic hypercalciuria. To adjust for the concentration differences in random urine specimens, calcium to creatinine ratio is included in the results. In general, 24-hour urine specimens are preferred to random urine specimens when measuring calcium for diagnostic evaluation of hypercalciuria [1].

Calcium is essential for bone formation and nerve, muscle, and heart functions. Calcium metabolism is jointly regulated by parathyroid hormone and vitamin D metabolites. Urinary calcium excretion is the major route of calcium elimination and reflects kidney tubular filtration and reabsorption of calcium in addition to dietary intake, intestinal absorption, and bone resorption [2].

Urinary calcium levels may be elevated in patients with idiopathic hypercalciuria, chronic kidney disease, hyperparathyroidism, vitamin D intoxication, Paget disease of bone, sarcoidosis, or conditions that infiltrate and destroy bones (eg, multiple myeloma and a variety of metastatic cancers) [2,3]. Urinary calcium levels may be decreased in patients with hypoparathyroidism, vitamin D deficiency rickets, osteomalacia, or familial hypocalciuric hypercalcemia [2,3].

Note that use of calcium supplements and loop diuretics may cause increased urinary calcium levels; thiazide diuretics may cause decreased urinary calcium levels [3].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

References
1. Williams JC Jr, et al. Urolithiasis. 2021;49(1):1-16.
2. Rifai N, et al. eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elservier Inc; 2022
3. MedlinePlus [Internet]. Calcium-urine. Accessed September 1, 2022. https://medlineplus.gov/ency/article/003603.htm

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.