What Is a Calcium Urine Test?

Medically Reviewed by Jennifer Robinson, MD on May 02, 2023
4 min read

You probably already know your body needs calcium for strong bones. You also need it for your heart, muscles, and nerves to work properly. Too much or too little calcium in your body can lead to serious health problems.

One way to check your calcium levels is with a calcium urine test.

It measures the amount of calcium in your pee. It’s a helpful tool for your doctor, and it’s painless for you, though it can take some time.

If your doctor has ordered a calcium urine test, it means they’re concerned that you might have one of these medical issues:

  • Kidney stones or kidney disease
  • Parathyroid disease, in which glands in your neck are either too active or not active enough, causing unhealthy levels of calcium in your blood
  • Bone health problems such as osteoporosis

Checking for calcium is likely not part of the routine urine test you might have at your annual physical. Your doctor will specifically order a calcium urine test if it appears your calcium levels are higher or lower than normal.

Normally, if levels in your system get too high, the extra calcium is just passed out of your body in your urine. Sometimes, calcium can crystallize and harden in your kidneys. These little clusters are called kidney stones.

They can be painful and hard to pass. Ultrasound can break up certain types of kidney stones with sound waves. Some kidney stones may require surgery for removal.

If you have a kidney stone, a calcium urine test can help your doctor decide how to treat it. Knowing what the stone is made of may affect how your doctor tries to remove it or break it up.

Not all kidney stones are made of calcium. Some are formed from uric acid, for example, and may be treated in a different way than those made of calcium.

Doctors can sometimes use calcium urine test results to figure out whether you’re likely to develop kidney stones in the future, usually a month or so after you’ve passed the previous stone.

A calcium urine test may also help your doctor understand why you have high calcium levels in your blood. You may hear your doctor or nurse call this “hypercalcemia.”

The most common cause of this condition is an overactive parathyroid gland.

You have four small parathyroid glands in your neck, each about the size of a single grain of rice. One of their main jobs is to make parathyroid hormone (PTH) to help keep a healthy calcium level in your body. Think of them as little thermostats that keep things in the right range.

Low calcium levels can trigger more PTH production by the parathyroid glands. This can cause a spike in calcium levels and throw your system off balance.

If you have brittle bones, a calcium urine test could be one of several lab tests to help find the cause of osteoporosis.

Your doctor may also check your vitamin D levels, your testosterone (for men), and your alkaline phosphatase levels, which help show how well you’re building new bone.

You probably won’t need to do anything unusual to get ready for the test. Some medications may affect the results, however. This means you should tell your doctor about all medications and supplements you take.

You may be asked to stop taking some medicine or supplement before the test or during the 24 hours of the test. Ask your doctor if you should change anything about your diet, or when and how you take your medicine. Don’t make these decisions on your own.

A calcium urine test is generally done over 24 hours. Different doctors and labs may do things a little differently, but usually you can expect to take these steps:

1. You’ll get a special container from your doctor or a lab to bring home.

2. On the morning of the first day of the test, you’ll pee as normal in the toilet right after you wake up.

3. Then you’ll pee only into the special container for the next 24 hours.

4. After you urinate into the container on the morning of the next day, you’ll seal it up.

5. Keep it in the refrigerator until you return it to your doctor’s office or a lab.

If you’re a parent or caregiver and you have an infant taking the test, you’ll be given a special set of instructions from your doctor about how to collect the samples.

If you follow a good diet and you have no health problems affecting your calcium levels, a normal test result would be 100 to 300 mg/day of calcium in your urine. If your diet is low in calcium, your result may be 50 to 150 mg/day of calcium in your urine.

Your doctor will talk with you about your results, what condition you may have, and what treatments or lifestyles changes may come next so you can get your calcium back to the right levels.

This test may be one of several you take to help your doctor diagnose your condition.