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Calcium Blood Test

What Is a Urine Calcium Test?

A urine calcium test measures how much calcium is passed out of the body through urine. The test is also known as the urinary Ca+2 test.

Calcium is the most common mineral in the body. It’s used for numerous functions, such as building and repairing bones and teeth. Calcium contributes to the functionality of your nerves, muscles, and heart. It also helps blood to clot.

Most calcium is stored in your bones. The remainder can be found in your blood. When calcium levels in your blood get too low, your bones release enough calcium to bring the level in the blood back to normal. When calcium levels get too high, the surplus of calcium is either stored in bones or expelled from the body through urine or stool.

The level of calcium present in your body depends on the following factors:

  • amount of calcium you get from food
  • amount of calcium and vitamin D the intestines absorb
  • level of phosphate in the body
  • certain hormone levels, including estrogen, calcitonin, and parathyroid hormone

People who have high or low levels of calcium usually don’t show any symptoms. Calcium levels often need to be extremely high or extremely low to prompt physical symptoms.

Why Is the Urine Calcium Test Performed?

Performing a urine calcium test can help your doctor evaluate:

  • whether high calcium levels in the urine resulted in a kidney stone
  • if your dietary intake of calcium is enough
  • how well your intestines are absorbing the calcium
  • conditions that lead to calcium loss from your bones
  • how well your kidneys are functioning
  • potential problems with the parathyroid gland

A blood calcium test is usually accurate in detecting certain conditions such as specific bone diseases, pancreatitis, and hyperparathyroidism.

Preparation for the Urinary Calcium Test

Your doctor may tell you to stop taking any medications that could affect the test results before the test. They may also ask you to follow a diet with a specific level of calcium for several days leading up to the test.

If the urine sample is being collected from your infant, your child’s doctor will provide special collection bags with instructions on how to collect the urine.

How Is the Urine Calcium Test Performed?

A urine calcium test measures the amount of calcium in the urine you produce in a 24-hour period. The test lasts from the morning of one day to the morning of the next.

These steps are usually followed for the urine test:

  1. On the first day, you’ll urinate after waking up. Don’t save this urine.
  2. Over the next 24 hours, you’ll collect all urine in the container your doctor gives you.
  3. On day two, you urinate into the container provided after waking up.
  4. During the 24-hour collection period, close the container and store it in the refrigerator after each time you urinate. Put your name on the container, as well as the date and time the test was completed.
  5. Return the sample as instructed by your doctor.

No risks are associated with the urine calcium test.

What Do the Test Results Mean?

Normal Results

The amount of calcium in the urine of a person eating a normal diet should be 100 to 250 mg/day. A diet low in calcium results in 50 to 150 mg/day of calcium in the urine.

Abnormal Results

Abnormally high calcium levels in the urine could be a sign of several syndromes or conditions, such as:

  • hyperparathyroidism: This happens when the parathyroid gland produces too much parathyroid hormone. Some symptoms include fatigue, back pain, and sore bones.
  • milk-alkali syndrome: This results from taking too much calcium. It’s usually seen in older women who take calcium to prevent osteoporosis.
  • idiopathic hypercalciuria: This occurs when there’s too much calcium in your urine for no reason.
  • sarcoidosis: This is a disease in which inflammation occurs in the lymph nodes, lungs, liver, eyes, skin, or other tissues.
  • renal tubular acidosis: When the kidneys aren’t making the urine acidic enough, high acid levels in the blood can occur.
  • vitamin D intoxication: This happens when there’s too much vitamin D in the body.
  • using loop diuretics: Also know as water pills, these medications work to increase water loss in the kidney, which can cause high levels.
  • renal failure: Kidney failure can also cause high levels.

Calcium levels in the urine that are abnormally low could point to:

  • malabsorption disorders: These can cause vomiting or diarrhea because nutrients have not been properly digested.
  • vitamin D deficiency: This means the body isn’t receiving enough vitamin D to function.
  • hypoparathyroidism: This is a disease in which the parathyroid doesn’t produce enough of a hormone to keep the calcium and phosphorus levels at proper levels.
  • thiazide diuretics: Another type of water pill, taking these can also cause low levels.

When to Talk to Your Doctor

Call your doctor to set up a consultation if you’re taking diuretics or think you’re experiencing one of the conditions listed above. Your doctor can help you work through any symptoms and decide if you need a urine calcium test.

Content licensed from:

Written by: Karla Blocka
Medically reviewed on: Dec 15, 2015: Mark R Laflamme MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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