Calcium - urine
This test measures the amount of calcium in urine. All cells need calcium in order to work. Calcium helps build strong bones and teeth. It is important for heart function, and helps with muscle contraction, nerve signaling, and blood clotting.
See also: Calcium - blood
How the Test is Performed
A 24-hour urine sample is usually needed:
A urine collection bag is needed for infants. This is a plastic bag with a sticky paper on one end. Wash the area around the child's urethra. For boys, place the entire penis in the bag and attach the adhesive to the skin. For girls, place the bag over the labia and secure into place with the adhesive. You can place a diaper over the bag.
This procedure may take a couple of attempts -- lively infants can move the bag. The infant should be checked often. Change the bag after the infant has urinated into it. Drain the urine into the container given to you by your health care provider and deliver it to the laboratory or doctor's office as soon as possible.
How to Prepare for the Test
Your doctor may tell you to temporarily stop taking any drugs that may affect the test results.
Drugs that may increase urine calcium measurements include antacids, anticonvulsants, carbonic anhydrase inhibitor diuretics, and loop diuretics.
Drugs that may decrease urine calcium measurements include adrenocorticosteroids, birth control pills, and thiazide diuretics.
NEVER stop taking any medicine without first talking to your doctor.
If the 24-urine collection is being taken from an infant, you may need a couple of extra collection bags.
How the Test Will Feel
The test involves only normal urination, and there is no discomfort.
Why the Test is Performed
Urine calcium levels can help your doctor:
If you are eating a normal diet, the expected amount of calcium in the urine is 100 to 300 mg/day. If you are eating a diet low in calcium, the amount of calcium in the urine will be 50 to 150 mg/day.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
Note: mg/day = milligrams per day
What Abnormal Results Mean
High levels of urine calcium (above 300 mg/day) may be due to:
Low levels of urine calcium may be due to:
There are no risks.
Bringhurst FR, Demay MB, Kronenberg HM. Hormones and disorders of mineral metabolism. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 28.
Wysolmerski JJ, Insogna KL. The parathyroid glands, hypercalcemia, and hypocalcemia. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 266.
Review Date: 6/1/2011
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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