Does this test have other names?
Total calcium, ionized calcium
What is this test?
A calcium blood test measures the amount of calcium circulating in your bloodstream. Your doctor can use this test to help diagnose and monitor a range of conditions that can occur. There are two types of calcium blood tests: total calcium and ionized calcium. Ionized calcium measures the "free" calcium in your blood - that is, the calcium not bound to other parts of the blood.
Why do I need this test?
Your health care provider may order a calcium blood test to help diagnose a variety of disorders, including kidney disease, pancreatitis, and disease of the parathyroid gland. Calcium levels may also be abnormal in many types of cancer. Your doctor might also order this test as part of a routine health check.
A normal calcium level in the blood is a good sign that several different areas of the body are likely functioning well. Calcium levels that are too low, called hypocalcemia, or too high, called hypercalcemia, can mean of a number of problems.
People with abnormal calcium levels may not have any symptoms. Severely low calcium levels can lead to seizures, irregular heartbeat, muscle spasms, or tingling in the hands or feet. People with high calcium levels may have nausea, vomiting, or severe thirst, constipation. Based on the results of a blood calcium test, your health care provider can figure out how to treat the underlying cause of any health problems you may be having.
What other tests might I have along with this test?
Calcium can be tested for a number of reasons. Additional tests will vary based on what your health care provider is looking for.
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. Some laboratories may have slightly different normal values than the ones below. 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.
A normal range of total blood calcium in adults is usually between 8.5 and 10.3 milligrams/deciliter (mg/dL). Ionized calcium generally should be higher than 4.6 mg/dL to be considered normal.
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
A number of things can affect the outcome of a calcium blood test. This test is typically done at the same time as other blood component tests to gain a greater picture of your overall health. Certain medications can change blood calcium levels and affect the test results.
How do I get ready for this test?
You don't need to prepare for this test. 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.
- Alteri, Rick, MD
- Marcellin, Lindsey, MD, MPH