Vitamin B12 Deficiency
(Vitamin B12 Dependency; Macrocytic Achylic Anemia)
|Red Blood Cells|
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- Removal of part of the small intestine or stomach
- Advancing age
Long-term use of certain acid-reducing stomach medications:
- H2 blockers
- Proton pump inhibitors
- Atrophic gastritis (inflammation of the stomach) due to:
- Disorders affecting vitamin absorption:
Inadequate intake of vitamin B12
- Long-term veganism (nonconsumption of animal products) or vegetarianism
- Breastfed infants of vegan or vegetarian mothers
- Poor infant nutrition
- Inadequate nutrition for a pregnant woman
- Chronic alcohol abuse
Stillness of the intestinal contents which can be caused by:
- Abnormal narrowness of intestines
- Pockets in intestines
- Connections between loops of the intestine
- Blind intestinal loops
- Intestinal blockage which can be caused by:
- Inflammation of the intestine due to radiation treatment
Inability to use vitamin B12:
- Lack of a needed enzyme
- Nonfunctioning transport protein
- Increased need of vitamin B12:
Over-use of nitrous oxide:
- Frequent use
- Extended single use of nitrous oxide (more than six hours)
- Methylmalonic aciduria
Use of certain drugs:
- Biguanides for diabetes
- Para-aminosalicylic acid for tuberculosis
- Calcium-chelating drugs taken by mouth
- Age: over 50 years old
- Strict vegan or vegetarian diet
- Sensation of pins and needles in feet or hands
- Alternating constipation and diarrhea
- Stinging sensation on the tongue or smooth red tongue
- Substantial weight loss
- Inability to distinguish the colors yellow and blue
- Loss of hunger
- Altered sense of taste
- Impaired sense of balance, especially in the dark
- Ringing in the ears
- Cracked lips
- Yellow skin
- Inability to sense vibrations in feet or legs
- Dizziness when changing to standing position
- Rapid heart rate
- Complete blood count (CBC)—a count of the number of red and white blood cells in a blood sample
- Vitamin B12 level—a test that measures the amount of vitamin B12 in the blood
- Methylmalonic acid (MMA) level—a measurement of the amount of methylmalonic acid in the blood; this test determines whether a vitamin B12 deficiency exists
- Homocysteine level—a test that measures the amount of homocysteine in the blood (homocysteine is a building block of protein); the homocysteine level will be elevated if there is a shortage of vitamin B12, folate, or vitamin B-6
- Schilling test—a test in which a harmless amount of radiation is used to assess whether a vitamin B12 deficiency exists (rarely used)
- Red blood cell folate level—a measurement of the amount of a B vitamin called folate
- Gastrin level—a test that may help determine the cause of a vitamin B12 deficiency
- Intrinsic factor assay—a measurement of the amount of a protein called intrinsic factor normally produced in the stomach; this test helps to rule out pernicious anemia as the cause of symptoms
- Bone marrow staining—a test that shows whether an iron deficiency exists
Oral Vitamin B12 Supplement
Vitamin B12 Injections
Treatment With Antibiotics
Intranasal Vitamin B12
Oral Iron Therapy
- Avoid long-term over-consumption of alcohol.
As directed by your doctor, take a daily supplement containing vitamin B12.
- As directed by your doctor, give vitamin B12 to your breastfed baby if you are a vegan or vegetarian.
- Avoid overuse of nitrous oxide.
- Seek diagnosis and treatment of any suspected tapeworm infestation.
- Have your doctor check you for iron deficiency.
- Undergo testing if your doctor suspects you are infected with the bacterium Helicobacter pylori.
Have your doctor monitor your health closely if you are taking the following drugs:
- Aminosalicylic acid
- Calcium-chelating drugs taken by mouth
American Academy of Family Physicians http://www.aafp.org
National Institutes of Health Office of Dietary Supplements http://ods.od.nih.gov
College of Family Physicians Canada http://www.cfpc.ca
Health Canada http://www.hc-sc.gc.ca/index%5Fe.html
Beers MH, Porter RS, et al., eds. The Merck Manual of Diagnosis and Therapy. 18th ed. Whitehouse Station, NJ: Merck Research Laboratories; 2006.
Beers MH, Berkow R, eds. The Merck Manual of Diagnosis and Therapy. 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999.
DynaMed Editorial Team. Pernicious anemia. EBSCO DynaMed website. Available at: https://dynamed.ebscohost.com/about/about-us. Updated April 27, 2010. Accessed November 11, 2010.
Kasper DL, Braunwald E, et al., eds. Harrison’s Principles of Internal Medicine. 16th ed. New York, NY: McGraw-Hill Companies, Inc; 2005.
Morrison G, Hark L, eds. Medical Nutrition and Disease. 2nd ed. Malden, MA: Blackwell Science, Inc; 1999.
Stipanuk MH. Biochemical and physiological aspects of human nutrition. Philadelphia, PA: WB Saunders Company; 2000.
Whitney EN, Rolfes SR. Understanding Nutrition. 9th ed. Belmont, CA: West/Wadsworth; 2002.
- Reviewer: Daus Mahnke, MD
- Review Date: 10/2012 -
- Update Date: 10/31/2012 -