Calcium is an essential mineral in your body. Calcium blood tests check to make sure you have appropriate levels of calcium in your blood to be healthy. If you have high or low levels of calcium in your blood, it may indicate that you have certain medical conditions.
A calcium blood test measures the level of calcium in your blood.
There are two types of calcium blood tests:
A calcium blood test cannot show how much calcium you have in your bones. Your healthcare provider can measure your bone health with a type of X-ray called a bone density test (DEXA scan).
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Calcium is one of the most important and common minerals in your body. About 99% of your body’s calcium is stored in your bones and teeth, while the other 1% of it circulates in your blood. Although it may be a small amount, the calcium in your blood is essential and does the following:
The levels of calcium in your blood and bones are controlled by two hormones called parathyroid hormone (PTH) and calcitonin. Vitamin D also plays an important role in maintaining calcium levels because your body needs it in order to absorb calcium.
There are four main reasons why you may need a calcium blood test, including:
Signs and symptoms of having too much calcium in your blood (hypercalcemia) include:
Signs and symptoms of having too little calcium in your blood (hypocalcemia) include:
Severe hypocalcemia (very low levels of calcium in your blood) can cause the following symptoms:
Your healthcare provider may order a calcium test if you have a medical condition that may affect your calcium levels. Many medical conditions affect your blood calcium levels, including:
Certain medications can also affect your blood calcium levels, including:
A healthcare provider known as a phlebotomist usually performs blood draws, but any healthcare provider who is trained in drawing blood can perform this task. The samples are sent to a lab where a medical laboratory scientist prepares the samples and performs the test on machines known as analyzers.
You don’t need to follow any special instructions before a calcium blood test if it’s your only test.
Your calcium blood test may be part of a basic or comprehensive metabolic panel, which measures multiple things in your blood. In this case, you may need to not eat or drink (fast) for several hours before your blood draw. In any case, your healthcare provider will let you know if you need to follow any special instructions.
You can expect to experience the following during a blood test, or blood draw:
The entire procedure usually takes less than five minutes.
After a healthcare provider has collected your blood sample, they’ll send it to a laboratory for testing. Once the test results are back, your healthcare provider will share the results with you.
Blood tests are a very common and essential part of medical testing and screening. There’s very little risk to having blood tests. You may have slight tenderness or a bruise at the site of the blood draw, but this usually resolves quickly.
Blood test reports, including calcium blood test reports, usually provide the following information:
In most cases, a normal blood calcium level for adults is 8.5 to 10.2 milligrams/deciliter (2.15 to 2.55 millimoles/liter). However, laboratories may have different reference ranges for normal blood calcium levels. You shouldn’t compare values from one laboratory to normal ranges from another laboratory.
When you get your blood test results back, there will be information that indicates what that lab’s normal blood calcium range is. If you have any questions about your results, be sure to ask your healthcare provider.
If your results reveal that you have higher-than-normal levels of calcium in your blood, it may indicate that you have:
It’s important to remember that a high calcium result doesn’t necessarily mean that you have a medical condition. Certain medications can also increase your blood calcium levels.
If your results reveal that you have lower-than-normal levels of calcium in your blood, it may indicate that you have:
It’s important to remember that a low calcium result doesn’t necessarily mean that you have a medical condition. Certain medications and diets can also decrease your blood calcium levels.
If your calcium blood test results reveal that you have high or low levels of calcium, it doesn't necessarily mean that you have a medical condition. Other factors, such as diet and certain medications, can affect your calcium levels. There could’ve also been an error in the collection, transport or processing of the test.
If you have an abnormal result, your healthcare provider may order additional tests to determine the cause of your abnormal calcium levels. The additional tests may measure your:
If you have questions about your results, don’t be afraid to talk to your healthcare provider.
In most cases, you should have your blood calcium test results within one or two days, though it could take longer.
If you’re experiencing concerning symptoms of hypocalcemia or hypercalcemia, contact your healthcare provider as soon as possible.
A note from Cleveland Clinic
Seeing an abnormal test result can be stressful. Know that having a high or low level of blood calcium doesn’t necessarily mean you have a medical condition and need treatment. Approximately 1 in 20 healthy people will have results outside of the normal range. Your healthcare provider will let you know if you need to undergo further tests to determine the cause of the abnormal level. Don’t be afraid to ask your provider questions. They’re there to help you.
Last reviewed by a Cleveland Clinic medical professional on 11/04/2021.
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