Vitamin B12 Deficiency
(Vitamin B12 Dependency; Macrocytic Achylic Anemia)
Pronounced: Vite-ah-min bee-twelv di-fish-ens-ee
by Monique Kahn, MS, RD
Vitamin B12 helps in red blood cell formation, production of DNA, and function of the nervous system.
Vitamin B12 deficiency can occur when the body needs more vitamin B12 than it receives from the diet. Alternatively, the condition may occur when the body is unable to use the vitamin B12 from the diet. A shortage of vitamin B12 can lead to anemia. Anemia occurs when levels of red blood cells are abnormally low and there is insufficient delivery of oxygen by red blood cells from the lungs to the cells of the body.
There are many causes of vitamin B12 deficiency, such as:
Risk Factors TOP
The following factors increase your chance of developing vitamin B12 deficiency:
The symptoms of pernicious anemia can vary from person-to-person. Symptoms may change or worsen over time.
Symptoms can include:
You will be asked about your symptoms and medical history. A physical exam will be done. Tests may include the following:
Talk with your doctor about the best treatment plan for you. Treatment options include the following:
Oral Vitamin B12 Supplement
This treatment consists of high doses of an oral vitamin B12 supplement.
Vitamin B12 Injections
The doctor may advise injections of vitamin B12 into a muscle. Injections of vitamin B12 may be given frequently at first. When blood tests show improvement, the injections may be given on a monthly basis.
Treatment With Antibiotics TOP
This type of medication may be needed in cases where bacterial overgrowth in the intestines exists. The bacteria compete with the body to absorb the vitamin B12 in the intestines.
Intranasal Vitamin B12 TOP
The doctor may advise a supplement of vitamin B12 that is placed in the nose.
To help reduce your chances of developing a deficiency of vitamin B12, take the following steps:
Family Doctor—American Academy of Family Physicians
National Institutes of Health Office of Dietary Supplements
College of Family Physicians of Canada
Pernicious anemia. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T116294/Pernicious-anemia. Updated August 9, 2013. Accessed September 26, 2016.
Vitamin B12. American Association of Clinical Chemistry website. Available at:
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Updated May 27, 2014. Accessed December 22, 2014.
Vitamin B12. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T233168/Vitamin-B12. Updated September 6, 2016. Accessed September 26, 2016.
Vitamin B12 deficiency. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T116899. Updated December 4, 2015. Accessed September 26, 2016.
Last reviewed December 2014 by Michael Woods, MD
Last Updated: 12/20/2014
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