What is a calcium (Ca) blood test?
A test for calcium in the blood checks the level of calcium in your body that is not stored in your bones. Almost all of the calcium in the body is stored in bone. The rest is found in the blood.
The body needs calcium to build and fix bones and teeth, to help nerves work, to make muscles squeeze together, to help blood clot, and to help the heart to work.
Why is a calcium (Ca) blood test done in children?
A blood calcium test may be done:
- To check for problems with the parathyroid glands or kidneys.
- To look for certain types of cancers and bone problems or for inflammation of the pancreas.
- To see if your child has a very low calcium level in the blood.
- To see if your child has a very high calcium level in the blood.
This test can't be used to check for a lack of calcium in your child's diet. It also can't check for a loss of calcium from your child's bones.
How is a calcium (Ca) blood test done?
A health professional uses a needle to take a blood sample, usually from the arm.
How do you prepare for a calcium (Ca) blood test?
In general, you don't need to prepare before having this test. Your doctor may give you some specific instructions.
What do the results of a calcium (Ca) blood test mean?
Normal
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
Normal blood calcium values are lower in older people.
You may also have values for an ionized calcium test. This test checks the amount of calcium that is not attached to protein in the blood. The level of ionized calcium in the blood is not affected by the amount of protein in the blood.
High values
High values of calcium may be caused by:
- Hyperparathyroidism.
- Cancer, including cancer that has spread to the bones.
- Tuberculosis.
- Being on bed rest for a long time.
- Paget's disease.
Low values
Low values of calcium may be caused by:
- A low level of the blood protein albumin (hypoalbuminemia).
- Hypoparathyroidism.
- High levels of phosphate in the blood. This can be caused by kidney failure, laxative use, and other things.
- Malnutrition caused by diseases such as celiac disease, pancreatitis, and alcohol use disorder.
- Osteomalacia.
- Rickets.
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