Calcium Blood Test
Reviewed
Also called: Total Calcium, Ionized Calcium, Ca Blood Test
A calcium blood test measures the amount of calcium in your blood. Too much or too little calcium may be a sign of a wide range of medical conditions, such as bone disease, thyroid disease, parathyroid disorders, kidney disease, and other conditions.
Specimen: Blood
Why this test may be ordered
- To check your general health as part of a routine checkup
- To help diagnose or monitor conditions that affect your bones, kidneys, digestive system, thyroid, and parathyroid glands
- If you have symptoms of high calcium levels such as constipation, nausea, increased thirst, or fatigue
- If you have symptoms of low calcium levels such as muscle cramps, tingling in lips or fingers, or irregular heartbeat
- If you have a known condition that may affect calcium levels, such as kidney disease, thyroid disease, or certain cancers
Preparation and collection
You usually don't need any special preparations. You may need to stop taking certain medicines or supplements, such as vitamin D, so tell your provider about everything you take. Do not stop taking any medicines unless your provider tells you to. If your provider has ordered more tests on your blood sample, you may need to fast for several hours before the test.
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. This usually takes less than five minutes.
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.
Understanding results
Results from a total calcium test that are higher or lower than normal may indicate various conditions. Your provider will interpret your results based on your overall health and other tests. The following are possible meanings of abnormal results.
- Higher than normal (hypercalcemia): May be a sign of overactive parathyroid glands (hyperparathyroidism), certain types of cancer including cancer that spreads to bone, bone disorders such as Paget's disease, or taking too much vitamin D over a long period of time. Limitation: A result higher than normal does not always mean you have a medical condition that needs treatment. Your diet and certain medicines can affect your calcium levels. Next step: Talk with your provider to understand what your result means and whether further testing is needed.
- Lower than normal (hypocalcemia): May be a sign of low blood protein levels (caused by liver disease or malnutrition), underactive parathyroid glands (hypoparathyroidism), too little calcium in your diet, too little vitamin D or magnesium, pancreatitis, or kidney disease. Limitation: A result lower than normal does not always mean you have a medical condition that needs treatment. Your diet and certain medicines can affect your calcium levels. Next step: Talk with your provider to understand what your result means and whether further testing is needed.
- A calcium blood test does not tell you how much calcium is in your bones.
- Results that are not in the normal range do not always mean you have a medical condition that needs treatment; diet and certain medicines can affect calcium levels.
- The test measures total calcium, which includes both bound and free calcium; an ionized calcium test may be needed if total calcium results are not normal.
What to do next
If you have questions about your results, talk with your provider. Your provider can explain what your results mean and whether any follow-up tests or actions are needed.
- What do my calcium test results mean for my health?
- Do I need any additional tests based on my calcium level?
- Should I change my diet or medications because of my calcium level?
- What symptoms should I watch for that might indicate a problem with my calcium levels?
- How often should I have my calcium levels checked?