Blood Calcium Test: About This Test

What is it?

A test for calcium in the blood checks the level of calcium in your body that is not stored in your bones. Almost all of the calcium in the body is stored in bone. The rest is found in the blood.

The body needs calcium to build and fix bones and teeth, to help nerves work, to make muscles squeeze together, to help blood clot, and to help the heart to work.

Why is this test done?

A blood calcium test may be done:

• To check for problems with the parathyroid glands or kidneys, certain types of cancers and bone problems, or inflammation of the pancreas (pancreatitis).
• To find a reason for an abnormal electrocardiogram (EKG) test.
• To see if you have a very low calcium level in your blood.
• To see if you have a very high calcium level in your blood.

A blood calcium test can't be used to check for a lack of calcium in your diet. And it doesn't look for the loss of calcium from your bones (osteoporosis). The body can have normal calcium levels even if your diet doesn't have enough calcium in it. Other tests, such as a bone density test, check for the amount of calcium in your bones.

How do you prepare for the test?

In general, you don't need to prepare before having this test. Your doctor may give you some specific instructions.

How is the test done?

A health professional uses a needle to take a blood sample, usually from the arm.

What happens after the test?

• You will probably be able to go home right away.
• You can go back to your usual activities right away.