Calcium (Blood)

Does this test have other names?

Total calcium, ionized calcium

What is this test?

A calcium blood test measures how much calcium is in your blood. Your healthcare provider can use this test to help diagnose and watch many conditions. There are two types of calcium blood tests. One is total calcium and the other is ionized calcium. Ionized calcium measures the “free” calcium in your blood. This is the calcium not bound to other parts of the blood.

Why do I need this test?

You may need this test if your healthcare provider is trying to diagnose a variety of disorders. These include kidney disease, pancreatitis, and disease of the parathyroid gland. The parathyroid gland is located in the neck. It makes a hormone that controls calcium levels in your blood. Calcium levels may also be abnormal in many types of cancer. Your healthcare provider might also order this test as part of a routine health check.

A normal calcium level in the blood is a good sign that your body is likely working as it should. Calcium levels that are too low (hypocalcemia) or too high (hypercalcemia) can mean a number of problems.

People with abnormal calcium levels may not have any symptoms. Very low calcium levels can cause seizures, irregular heartbeat, muscle spasms, or tingling in the hands or feet. People with high calcium levels may have nausea, vomiting, severe thirst, or constipation. Your healthcare provider will use the results of a blood calcium test to figure out how to treat the underlying cause of any health problems you may have.

What other tests might I have along with this test?

Calcium can be tested for a number of reasons. Other tests will vary based on what your healthcare provider is looking for. 

Your provider may also order tests to check kidney function, vitamin D, phosphorus levels, and parathyroid hormone. These tests can help figure out what is causing your abnormal calcium levels.

What do my test results mean?

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

A normal range of total blood calcium in adults is usually between 8.5 and 10.3 milligrams/deciliter (mg/dL). A normal ionized calcium level generally ranges between 4.6 to 5.3 mg/dL. 

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

What might affect my test results?

A number of things can affect the results of a calcium blood test. This test is typically done at the same time as other blood tests to get a better picture of your overall health. Certain medicines, such as certain types of diuretics, can change blood calcium levels and affect the test results. 

How do I get ready for this test?

You don’t need to get ready for this test. 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 illegal drugs you may use.