Alternative Names urinary calcium excretion, calcium, 24 hour urine
Definition This test measures the amount of calcium in urine.
Calcium is needed for many cellular functions. It is especially important for bone structure and muscle activity. The amount of calcium in urine can help find and monitor disorders involving calcium regulation.
Who is a candidate for the test? This test is ordered to help diagnose diseases of the kidneys, parathyroid glands, or bones.
How is the test performed? This test is performed on a urine sample collected over 24 hours.
In general, this schedule is followed: On the first day, the person should urinate as usual after getting up. This sample is not saved. Then all urine produced for the next 24 hours is collected in a special container. The next morning's urine is added to the day's collection. The sample must be refrigerated until it is delivered to a doctor.
What is involved in preparation for the test? A doctor provides specific instructions. Generally, no special preparation is required.
What do the test results mean? Normal levels of calcium in urine range from up to 7.5 mmols/L (millimoles per litre) for persons on a normal diet. For those on a low-calcium diet, from 1.25 - 3.75 mmols/L is normal.
Abnormally high levels of calcium in the urine may indicate:
idiopathic hypercalcaemia, which is an elevated calcium level in the blood with no known cause
milk-alkali syndrome, which is an increased blood calcium level caused by ingesting large amounts of calcium and antacids
osteolytic bone disease, which is any disease that destroys bone
osteoporosis, a thinning of the bones that commonly occurs in the elderly
primary hyperparathyroidism, which is excess activity of the parathyroid gland that causes increased blood calcium levels
renal tubular acidosis, a metabolic defect of the kidneys
sarcoidosis, a disease, thought to be caused by an abnormal immune system, that causes problems in multiple areas of the body but especially the lungs
vitamin D intoxication
idiopathic hypercalciuria, a condition the where body excretes excess calcium despite a normal calcium level in the blood
Abnormally low levels of calcium may indicate:
hypoparathyroidism, or low activity of the parathyroid gland
renal osteodystrophy or thinning of bones caused by kidney failure
vitamin D deficiency
Author: Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 15/03/2005 Contributors Potential conflict of interest information for reviewers available on request
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