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Test Code CALC5 Calcium, Random, Urine


Specimen Required


Only orderable as part of a profile. For more information see CACR3 / Calcium/Creatinine Ratio, Random, Urine

 

Supplies: Sarstedt Aliquot Tube 5 mL (T914)

Collection Container/Tube: Clean, plastic urine container with no metal cap or glued insert

Submission Container/Tube: Plastic, 5-mL tube or a clean, plastic aliquot container with no metal cap or glued insert

Specimen Volume: 4 mL

Collection Instructions:

1. Collect a random urine specimen.

2. No preservative.


Useful For

Measurement of calcium for the evaluation of calcium oxalate and calcium phosphate kidney stone risk, and calculation of urinary supersaturations

 

Evaluation of bone diseases, including osteoporosis and osteomalacia

Method Name

Only orderable as part of a profile. For more information see CACR3 / Calcium/Creatinine Ratio, Random, Urine

 

Photometric

Reporting Name

Calcium, Random, U

Specimen Type

Urine

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 14 days
  Frozen  30 days
  Ambient  72 hours

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

Calcium is the fifth most common element in the body. It is a fundamental element necessary to form electrical gradients across membranes, an essential cofactor for many enzymes, and the main constituent in bone. Under normal physiologic conditions, the concentration of calcium in serum and in cells is tightly controlled. Calcium is excreted in both urine and feces. Ordinarily about 20% to 25% of dietary calcium is absorbed, and 98% of filtered calcium is reabsorbed in the kidney. Traffic of calcium between the gastrointestinal tract, bone, and kidney is tightly controlled by a complex regulatory system that includes vitamin D and parathyroid hormone. Sufficient bioavailable calcium is essential for bone health. Excessive excretion of calcium in the urine is a common contributor to kidney stone risk.

Reference Values

Only orderable as part of a profile. For more information see CACR3 / Calcium/Creatinine Ratio, Random, Urine

 

1 month-<12 months: 0.03-0.81 mg/mg creatinine

12 months-<24 months: 0.03-0.56 mg/mg creatinine

24 months-<3 years: 0.02-0.50 mg/mg creatinine

3 years-<5 years: 0.02-0.41 mg/mg creatinine

5 years-<7 years: 0.01-0.30 mg/mg creatinine

7 years-<10 years: 0.01-0.25 mg/mg creatinine

10 years-<18 years: 0.01-0.24 mg/mg creatinine

18 years-83 years: 0.05-0.27 mg/mg creatinine

Reference values have not been established for patients who are younger than 1 month of age.

Reference values have not been established for patients who are older than 83 years of age.

Interpretation

Increased urinary calcium excretion (hypercalciuria) is a known contributor to kidney stone disease and osteoporosis.

 

Many cases are genetic (often termed "idiopathic"). Previously such patients were often divided into fasting versus absorptive hypercalciuria depending on the level of urine calcium in a fasting versus fed state, but the clinical utility of this approach is now in question. Overall, the risk of stone disease appears increased when 24-hour urine calcium is greater than 250 mg in men and greater than 200 mg in women. Thiazide diuretics are often used to reduce urinary calcium excretion and repeat urine collections can be performed to monitor the effectiveness of therapy.

 

Known secondary causes of hypercalciuria include hyperparathyroidism, Paget disease, prolonged immobilization, vitamin D intoxication, and diseases that destroy bone (such as metastatic cancer or multiple myeloma).

 

Urine calcium excretion can be used to gauge the adequacy of calcium and vitamin D supplementation, for example in states of gastrointestinal fat malabsorption that are associated with decreased bone mineralization (osteomalacia).

Method Description

Calcium ions react with 5-nitro-5'-methyl-BAPTA (NM-BAPTA) under alkaline conditions to form a complex. This complex reacts in the second step with EDTA. The change in absorbance is directly proportional to the calcium concentration and is measured photometrically.(Package insert: Roche CA2 kit. Roche Diagnostics; V2.0 07/2012)

Specimen Retention Time

7 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

82310

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CALC5 Calcium, Random, U 17862-4

 

Result ID Test Result Name Result LOINC Value
CALC5 Calcium, Random, U 17862-4

Day(s) Performed

Monday through Sunday

Report Available

1 to 3 days