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Calcium Blood Test

What is a Calcium Blood Test?

A calcium blood test measures the amount of calcium in your blood. Calcium is one of the most important minerals in your body. You need calcium for healthy bones and teeth. Calcium is also essential for proper functioning of your nerves, muscles, and heart. About 99% of your body's calcium is stored in your bones. The remaining 1% circulates in the blood. If there is too much or too little calcium in the blood, it may be a sign of bone disease, thyroid disease, kidney disease, or other medical conditions.

Other names: total calcium, ionized calcium

What is it used for?

There are two types of calcium blood tests:

  • Total calcium, which measures the calcium attached to specific proteins in your blood.
  • Ionized calcium, which measures the calcium that is unattached or "free" from these proteins.

Total calcium is often part of a routine screening test called a basic metabolic panel. A basic metabolic panel is a test that measures different minerals and other substances in the blood, including calcium.

Why do I need a calcium blood test?

Your health care provider may have ordered a basic metabolic panel, which includes a calcium blood test, as part of your regular checkup, or if you have symptoms of abnormal calcium levels.

Symptoms of high calcium levels include:

Symptoms of low calcium levels include:

Many people with high or low calcium levels do not have any symptoms. Your health care provider may order a calcium test if you have a pre-existing condition that may affect your calcium levels. These include:

  • Kidney disease
  • Thyroid disease
  • Malnutrition
  • Certain types of cancer

What happens during a calcium blood 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. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You don't need any special preparations for a calcium blood test or a basic metabolic panel. If your health care provider has ordered more tests on your blood sample, you may need to fast (not eat or drink) for several hours before the test. Your health care provider will let you know if there are any special instructions to follow.

Are there any risks to the test?

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.

What do the results mean?

If your results show higher than normal calcium levels, it may indicate:

  • Hyperparathyroidism, a condition in which your parathyroid glands produce too much parathyroid hormone
  • Paget's disease of the bone, a condition that causes your bones to become too big, weak, and prone to fractures
  • Overuse of antacids that contain calcium
  • Excessive intake of calcium from vitamin D supplements or milk
  • Certain types of cancer

If your results show lower than normal calcium levels, it may indicate:

  • Hypoparathyroidism, a condition in which your parathyroid glands produce too little parathyroid hormone
  • Vitamin D deficiency
  • Magnesium deficiency
  • Inflammation of the pancreas (pancreatitis)
  • Kidney disease

If your calcium test results are not in the normal range, it doesn't necessarily mean that you have a medical condition needing treatment. Other factors, such as diet and certain medicines, can affect your calcium levels. If you have questions about your results, talk to your health care provider.

Is there anything else I need to know about a calcium blood test?

A calcium blood test does not tell you how much calcium is in your bones. Bone health can be measured with a type of x-ray called a bone density scan, or dexa scan. A dexa scan measures the mineral content, including calcium, and other aspects of your bones.

References

  1. Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Calcium, Serum; Calcium and Phosphates, Urine; 118–9 p.
  2. Lab Tests Online [Internet]. American Association for Clinical Chemistry; c2001–2017. Calcium: The Test [updated 2015 May 13; cited 2017 Mar 30]; [about 4 screens]. Available from: https://labtestsonline.org/understanding/analytes/calcium/tab/test
  3. Lab Tests Online [Internet]. American Association for Clinical Chemistry; c2001–2017. Calcium: The Test Sample [updated 2015 May 13; cited 2017 Mar 30]; [about 3 screens]. Available from: https://labtestsonline.org/understanding/analytes/calcium/tab/sample
  4. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Types of Blood Tests [updated 2012 Jan 6; cited 2017 Mar 30]; [about 4 screens]. Available from: https://www.nhlbi.nih.gov/health/health-topics/topics/bdt/types
  5. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; What Are the Risks of Blood Tests? [updated 2012 Jan 6; cited 2017 Mar 30]; [about 6 screens]. Available from: https://www.nhlbi.nih.gov/health/health-topics/topics/bdt/risks
  6. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; What Do Blood Tests Show? [updated 2012 Jan 6; cited 2017 Mar 30]; [about 7 screens]. Available from: https://www.nhlbi.nih.gov/health/health-topics/topics/bdt/show
  7. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; What To Expect with Blood Tests [updated 2012 Jan 6; cited 2017 Mar 30]; [about 5 screens]. Available from: https://www.nhlbi.nih.gov/health/health-topics/topics/bdt/with
  8. NIH National Osteoporosis and Related Bone Diseases National Resource Center [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Questions and Answers about Paget's Disease of Bone; 2014 Jun [cited 2017 Mar 30]; [about 2 screens]. Available from: https://www.niams.nih.gov/Health_Info/Bone/Pagets/qa_pagets.asp
  9. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2017. Hypercalcemia (High Level of Calcium in the Blood) [cited 2017 Mar 30]; [about 2 screens]. Available from: http://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/hypercalcemia-high-level-of-calcium-in-the-blood
  10. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2017. Hypocalcemia (Low Level of Calcium in the Blood) [cited 2017 Mar 30]; [about 2 screens]. Available from: http://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/hypocalcemia-low-level-of-calcium-in-the-blood
  11. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2017. Overview of Calcium's Role in the Body [cited 2017 Mar 30]; [about 2 screens]. Available from: http://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/overview-of-calcium-s-role-in-the-body
  12. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2017. Health Encyclopedia: Bone Density Test [cited 2017 Mar 30]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=92&contentid=P07664
  13. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2017. Health Encyclopedia: Calcium [cited 2017 Mar 30]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=19&contentid=Calcium
  14. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2017. Health Encyclopedia: Calcium (Blood) [cited 2017 Mar 30]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=calcium_blood

The medical information provided is for informational purposes only, and is not to be used as a substitute for professional medical advice, diagnosis or treatment. Please contact your health care provider with questions you may have regarding medical conditions or the interpretation of test results.

In the event of a medical emergency, call 911 immediately.