Calcium Blood Test

Calcium Blood Test

Calcium is an important mineral for the human body to function properly. Calcium helps build strong bones and teeth, as well as providing essential electrolytes for muscle and nerve functioning. A calcium blood test, also known as a serum calcium test, measures the amount of calcium in the bloodstream and is typically used to diagnose and monitor conditions relating to calcium levels. Here is an overview of what the calcium blood test is, what it is used for, how to prepare for it, the types, risks, and other considerations.


No specific preparation is required for a serum calcium test, though it is recommended to fast for up to 8 hours prior to the test. This ensures that the results of your calcium test are not affected by your dietary calcium intake.


A serum calcium test is typically conducted by a laboratory technician, nurse or doctor. You will be asked to provide a sample of your blood, which is then sent to a laboratory for testing. After the test, the results will be provided to your doctor who will interpret them.


There are two types of calcium blood tests: ionized and total calcium tests. The ionized calcium test measures the active, “free” form of calcium in the blood, while the total calcium test measures both the “free” and the bound forms of calcium. The latter test is the most commonly used, as it is able to detect both active and inactive forms of calcium.


The calcium blood test is a very safe, non-invasive procedure. However, there is a small risk of bruising at the injection site, as well as a slight risk of infection from the needle. Your doctor may advise you of any other potential risks in advance.

Why It's Done

The calcium blood test is typically used to diagnose and monitor conditions that affect calcium levels. These can include chronic kidney disease, vitamin D deficiency, thyroid dysfunction and cancer. The test can also be used to monitor the effects of calcium-containing medications, such as calcium supplements and antacids.

When To Get Tested

Your doctor may recommend that you get a calcium blood test if they suspect that you may have a condition that could be affecting your calcium levels. Additionally, it is common to have a calcium blood test performed periodically in order to monitor your overall calcium levels. If your doctor has recommended a calcium blood test, it is important to follow their instructions.