Calcium is the most plentiful mineral in your body. Your body uses it to:
- Strengthen your bones and teeth
- Contract your muscles
- Narrow and widen blood vessels
- Send and receive nerve messages
- Release hormones
- Clot your blood
Almost all of your body’s calcium is stored in your bones. A very small amount — about 1% — is in your blood.
Calcium in your blood comes in two forms:
- Free calcium is not attached to anything else in your blood.
- Bound calcium is attached to a protein called albumin or other substances in your blood.
There are two types of blood calcium tests:
- A total calcium test measures both free and bound calcium. It’s the type of blood calcium test doctors order most often.
- An ionized calcium test measures only free calcium.
- When Would I Get This Test?
A calcium blood test is done during a regular health exam. You might have a comprehensive metabolic panel that also tests for blood sugar, protein, and other important substances.
- You might get a calcium blood test if you have a disease that can affect your levels of this mineral, such as:
- Bone disease (osteoporosis, for example)
- Cancer of the breast, lung, kidney, head, and neck, or multiple myeloma
- Kidney or liver disease
- Nerve problem
- Overactive thyroid gland
- Pancreatitis, which is inflammation of the pancreas
- Parathyroid disease, in which glands in your neck are either too active or not active enough, causing unhealthy levels of calcium in your blood
- Problem absorbing nutrients from food in your intestines
- You might also get this test if you have an EKG heart test that has certain abnormalities.
- This test can check how well your body is reacting to treatments for some of these conditions. And, it can be used to monitor the side effects of medicines you take.
- Another reason to get this test is if you have symptoms of high calcium, which include:
- No desire to eat
- Always tired
- Intense thirst
- Stomach pain
- Or if you have symptoms of low calcium, like these:
- Irregular heartbeat
- Muscle cramps or spasms
- Tingling in your hands or feet
Some medications can affect the results of your calcium blood test which includes:
- Diuretics for high blood pressure
- Lithium for bipolar disorder
- Vitamin D supplements
- Thiazide diuretics
- Calcium supplements
Normal blood calcium results in adults are:
Total blood calcium: 8.5 to 10.5 milligrams per deciliter (mg/dL)
Ionized calcium: 4.65 to 5.2 mg/d