Calcium (Fasting) Test

Calcium is an important mineral that your body uses in many ways. It increases the strength of your bones and teeth and helps your muscles and nerves function. Calcium can be used as a diagnostic test if a person has symptoms that suggest: Kidney stones Bone disease Neurologic disorders The calcium blood test is ordered to screen for, diagnose, and monitor a range of conditions relating to the bones, heart, nerves, kidneys, and teeth. The test may also be ordered if a person has symptoms of a parathyroid disorder, malabsorption, or an overactive thyroid. It measures the total calcium in your blood.

You’ll need to fast for six hours before you have your blood drawn for a calcium test. This means you shouldn’t eat or drink anything other than water during that time. Discuss your current medications with your doctor. You may have to stop taking certain medications before the test, but only if your doctor tells you to do so. Don’t stop taking a medication without talking to your doctor about it first. Your health care provider will let you know if there are any special instructions to follow.

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. If your calcium test results are not in the normal range, it doesn't necessarily mean that you have a medical condition needing treatment. Other factors, such as diet and certain medicines, can affect your calcium levels. If you have questions about your results, talk to your health care provider.

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes. You may feel some moderate pain or a mild pinching sensation during the procedure. After your doctor removes the needle, you may feel a throbbing sensation. You’ll be instructed to apply pressure to the site where the needle entered your skin. Your arm will then be bandaged. You should avoid using that arm for heavy lifting for the rest of the day.