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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 parathyroid gland regulates the calcium in your body. It releases extra calcium from the bones when your body needs it. If your body has too much calcium, it is carried out of your body with your urine.

If the calcium in your urine builds up and crystallizes, you may develop kidney stones. These can cause pain on either side of your lower back. Although kidney stones can form from other things in the urine, calcium stones are the most common.

You can also develop stones if your kidneys absorb too much calcium. Your diet, including how much fluid you drink, can also lead to 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 make in a 24-hour period so that it can be looked at in a lab.

Why do I need this test?

You may need this test if your healthcare provider 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 healthcare provider may also order other tests. These include:

  • Calcium blood test

  • CT scan

  • Ultrasound

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. 

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 lower the calcium level in your urine, your healthcare provider 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 provider may recommend that you add more potassium and reduce the amount of salty foods in your diet. Cutting back on the amount of calcium you eat likely won't lower your risk for stones. This is true unless you eat very large quantities of calcium.

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

How is this test done?

This test needs a 24-hour urine sample. For this sample, you must collect all of your urine for 24 hours. Empty your bladder completely first in the morning without collecting it. Note the time. Then collect your urine every time you go to the bathroom over the next 24 hours. 

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. Your test results can also be affected if you do not collect all urine samples in a 24-hour period. To get accurate results follow the directions your healthcare provider gives you.

How do I get ready for this test?

You don't need to prepare for this test. But be sure your healthcare provider 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. 

If you are doing a 24-hour test, make sure you understand how to collect the sample. Ask if there are any foods you should not eat before or during the test. 

Medical Reviewers:

  • Greco, Frank MD
  • Sather, Rita, RN