Chilton Medical Center - ATLANTIC HEALTH SYSTEM
Decrease (-) Restore Default Increase (+)  font size
PrintEmail
Search Health Information   

Blood test
Blood test


25-hydroxy vitamin D test

Definition:

The 25-hydroxy vitamin D test is the most accurate way to measure how much vitamin D is in your body.

In the kidney, 25-hydroxy vitamin D changes into an active form of the vitamin. The active form of vitamin D helps control calcium and phosphate levels in the body.

This article discusses the blood test used to measure the amount of 25-hydroxy vitamin D.



Alternative Names:

25-OH vitamin D test; Calcidiol; 25-hydroxycholecalciferol test



How the Test is Performed:

A blood sample is needed.



How to Prepare for the Test:

Usually you will not need to fast. However, this depends on the laboratory and the testing method used.



How the Test Will Feel:

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing.



Why the Test is Performed:

This test is done to determine if you have too much or too little vitamin D in your blood.



Normal Results:

The normal range of vitamin D is measured as nanograms per milliliter (ng/mL). Many experts recommend a level between 20 and 40 ng/mL. Others recommend a level between 30 and 50 ng/mL.

The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some laboratories use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results, and whether you may need vitamin D supplements.



What Abnormal Results Mean:

Lower-than-normal levels can be due to a vitamin D deficiency, which can result from:

  • Lack of exposure to sunlight
  • Lack of enough vitamin D in the diet
  • Liver and kidney diseases
  • Poor food absorption
  • Use of certain medicines, including phenytoin, phenobarbital, and rifampin

Low vitamin D levels are more common in African-American children (especially in the winter), as well as in infants who are breastfed only. Low vitamin D levels have also been associated with an increased risk of developing cancer. For more information, see the article on vitamin D deficiency .

Higher-than-normal levels may be due to excess vitamin D, a condition called hypervitaminosis D .



Risks:

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

  • Excessive bleeding
  • Fainting or feeling light-headed
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)


References:

Dawson-Hughes B, Mithal A, Bonjour JP, et al. IOF position statement: vitamin D recommendations for older adults. Osteoporosis Int. 2010;21:1151-1154.

Dietary Reference Intakes for Calcium and Vitamin D: Institute of Medicine Brief Report. www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Report-Brief.aspx

Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 201;96:1911-1930.




Review Date: 8/3/2014
Reviewed By: Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
adam.com


Morristown Medical Center
100 Madison Avenue
Morristown, NJ 07960
973-971-5000

Overlook Medical Center
99 Beauvoir Avenue
Summit, NJ 07901
908-522-2000

Newton Medical Center
175 High Street
Newton, NJ 07860
973-383-2121

Chilton Medical Center
97 West Parkway
Pompton Plains, NJ 07444
973-831-5000

Hackettstown Medical Center
651 Willow Grove Street
Hackettstown, NJ 07840
908-852-5100

Goryeb Children's Hospital
100 Madison Avenue
Morristown, NJ 07960
973-971-5000

Atlantic Medical Group
1-800-247-9580

Morristown Medical Center

100 Madison Avenue
Morristown, NJ 07960
973-971-5000

Overlook Medical Center

99 Beauvoir Avenue
Summit, NJ 07901
908-522-2000

Newton Medical Center

175 High Street
Newton, NJ 07860
973-383-2121

Chilton Medical Center

97 West Parkway
Pompton Plains, NJ 07444
973-831-5000

Hackettstown Medical Center

651 Willow Grove Street
Hackettstown, NJ 07840
908-852-5100

Goryeb Children's Hospital

100 Madison Avenue
Morristown, NJ 07960
973-971-5000

Affiliated Providers

Atlantic Medical Group

More than 600 community-based health care providers.
1-800-247-9580

© 2016 Chilton Medical Center, 97 West Parkway, Pompton Plains, New Jersey 1-973-831-5000