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:
- On day 1, urinate into the toilet when you wake up in the morning.
- Collect all urine (in a special container) for the next 24 hours.
- On day 2, urinate into the container in the morning when you wake up.
- Cap the container. Keep it in the refrigerator or a cool place during the collection period. Label the container with your name, the date, and the time you finish it, and return it as instructed.
For an infant, thoroughly wash the area where urine exits the body.
- Open a urine collection bag (a plastic bag with an adhesive paper on one end).
- For males, place the entire penis in the bag and attach the adhesive to the skin.
- For females, place the bag over the labia.
- Diaper as usual over the secured bag.
This procedure may take a few tries. An active baby can move the bag, causing urine to go into the diaper. You may need extra collection bags.
Check the infant often and change the bag after the infant has urinated into it. Drain the urine from the bag into the container provided by your health care provider.
Deliver the sample to the laboratory or to your health care provider as soon as possible.
How to Prepare for the Test
Many medicines can interfere with blood test results.
- Your health care provider will tell you if you need to stop taking any medicines before you have this test.
- Do not stop or change your medications without talking to your doctor first.
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:
Chronic kidney disease
Leaking of calcium from the kidneys into the urine, which causes calcium kidney stones
Taking too much calcium
Too much production of parathyroid hormone (PTH) by the parathyroid glands in the neck (hyperparathyroidism)
- Use of diuretics ("water pills")
Low levels of urine calcium may be due to:
Disorders in which the body does not absorb nutrients from food well
Disorders in which the kidney handles calcium abnormally
Parathyroid glands in the neck do not produce enough PTH (hypoparathyroidism)
- Use of a water pill called a thiazide diuretic
- Very low levels of vitamin D
Wysolmerski JJ, Insogna KL. The parathyroid glands, hypercalcemia, and hypocalcemia. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 253.
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, Bethanne Black, and the A.D.A.M. Editorial team.