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Calcium (Urine)

Does this test have other names?

Urinalysis (calcium)

What is this test?

This test measures the level of calcium in your urine.

Your body uses calcium in many ways, from developing teeth to building bones. Your bones regulate the calcium in your body, releasing extra calcium when your body needs it. If your body has too much calcium, it's carried out with your urine.

If the calcium in your urine builds up and crystallizes, you may develop kidney stones. Although kidney stones can form from other compounds in the urine, calcium stones are the most common.

You can also develop stones if your kidneys absorb an abnormal amount of calcium. Your diet, including how much fluid you drink, can also contribute to the creation of kidney stones. Drinking too little water means that you'll make less urine and more calcium can build up.

Your body tries to get rid of kidney stones by sending them out through your bladder. Kidney stones can be quite painful, especially when you urinate.

For this test, you collect all the urine you produce in a 24-hour period so that it can be looked at in a lab.

Why do I need this test?

You may have this test if your doctor needs to see how well your kidneys are working, especially if you get kidney stones.  

What other tests might I have along with this test?

Your doctor may also order other tests, including:

  • Calcium blood test

  • CT scan

  • Ultrasound

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

Results are given in milligrams per day (mg/day). A normal level of calcium in the urine is less than 45 mg/day.

If your results are higher, it may mean you are at risk for kidney stones. The risk for kidney stones rises at levels greater than 100 mg/day. The higher the reading, the greater the risk is for both men and women.

To reduce the calcium level in your urine, your doctor might suggest that you eat more vegetables and fruits and less animal products, like red meat and eggs. If you're an older adult, your doctor may recommend that you add more potassium to your diet. Cutting back on the amount of calcium you eat – unless you take in large amounts – likely won't lower your risk for stones.

If your results are lower, it may mean you have a lack of vitamin D. 

How is this test done?

This test requires a 24-hour urine sample. For this type of urine sample, you must collect all the urine your produce for 24 hours. Empty your bladder completely first thing in the morning without collecting it and note the time. Then collect your urine every time you go to the bathroom for the next 24 hours, including the first time the next morning. 

Does this test pose any risks?

This test poses no known risks.

What might affect my test results?

Eating meat and eggs can affect your results.

How do I get ready for this test?

You don't need to prepare for this test. But be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.