All cells need calcium in order to work. Calcium helps build strong bones and teeth. It is important for heart function, and helps with muscle contraction, nerve signaling, and blood clotting.
This article discusses the test to measure the total amount of calcium in your blood.
Calcium can also be measured in the urine. See: Calcium - urine test
Ca+2; Serum calcium; Ca++
A blood sample is needed. For information on how this is done, see: Venipuncture
Your health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test.
Drugs that can increase calcium levels include:
Drinking too much milk (two or more quarts a day) or taking too much vitamin D as a dietary supplement can also increase blood calcium levels.
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Your doctor may order this test if you have signs or symptoms of:
Your doctor may also order this test if you have been on bed rest for a long time.
About half of the calcium in the blood is attached to proteins. A separate test measures calcium that is not attached to proteins in your blood. Such calcium is called free or ionized calcium. See: Calcium - ionized
Normal values range from 8.5 to 10.2 mg/dL.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
Higher than normal levels may be due to a number of health conditions. Common causes include:
Lower than normal levels may be due to:
Wysolmerski JJ, Insogna KL. The parathyroid glands, hypercalcemia, and hypocalcemia. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 253.