Calcium Blood Test
Reviewed
A calcium blood test measures the amount of calcium in your blood. Too much or too little calcium may be a sign of a wide range of medical conditions, such as bone disease, thyroid disease, parathyroid disorders, kidney disease, and other conditions.
Preparation and collection
You usually don't need any special preparations. You may need to stop taking certain medicines or supplements, such as vitamin D, so tell your provider about everything you take. Do not stop taking any medicines unless your provider tells you to. If your provider has ordered more tests on your blood sample, you may need to fast for several hours before the test.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- A calcium blood test does not tell you how much calcium is in your bones.
- Results that are not in the normal range do not always mean you have a medical condition that needs treatment; diet and certain medicines can affect calcium levels.
- The test measures total calcium, which includes both bound and free calcium; an ionized calcium test may be needed if total calcium results are not normal.
What to do next
If you have questions about your results, talk with your provider. Your provider can explain what your results mean and whether any follow-up tests or actions are needed.