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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. Measuring the amount of calcium in urine can help diagnose 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:

• Day 1: The person urinates upon arising (for example at 7 a.m.) without collecting that sample. After that, he or she collects all of his or her urine for the next 24 hours in a special container.
• Day 2: First thing the following morning (at 7 a.m.), the person urinates into the container again. Then the individual covers it and refrigerates it. The sample is brought to the doctor, who will send it to the lab for the analysis.

The sample must be refrigerated until it is delivered to a healthcare professional.

What is involved in preparation for the test?

A healthcare professional provides specific instructions. Generally, no special preparation is required.

What do the test results mean?

Normal levels of calcium in urine range from 100 to 300 milligrams per day for persons on a normal diet. For those on a low-calcium diet, from 50 to 150 milligrams per day is normal.

Abnormally high levels of calcium in the urine may indicate:

• Cushing's syndrome, an excess of hormones known as corticosteroids
• idiopathic hypercalcemia, an elevated calcium level in the blood with no known cause
• milk-alkali syndrome, an increased blood calcium level caused by ingesting large amounts of calcium and antacids
• osteolytic bone disease, any disease that destroys bone
• osteoporosis, a thinning of the bones that commonly occurs in the elderly
• primary hyperparathyroidism, excess activity of the parathyroid gland that causes increased blood calcium levels
• renal tubular acidosis, a metabolic defect of the kidneys
• sarcoidosis, an inflammatory condition that causes abnormal lumps of tissue to form in multiple areas of the body but especially the lungs
• vitamin D intoxication

Abnormally low levels of calcium may indicate:

• hypoparathyroidism, low activity of the parathyroid gland
• malabsorption disorders
• renal osteodystrophy, a thinning of bones caused by kidney failure
• vitamin D deficiency