Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues.
Vitamin B12 deficiency anemia is a low red blood cell count due to a lack of vitamin B12.
Your body needs vitamin B12 to make red blood cells. In order to provide vitamin B12 to your cells:
A lack of vitamin B12 in the diet may be due to:
A number of problems can make it difficult for your body to absorb enough vitamin B12:
People with mild anemia may have no symptoms, or symptoms may be very mild.
More typical symptoms of vitamin B12 deficiency anemia include:
Symptoms from nerve damage caused by vitamin B12 deficiency that has been present for a longer time include:
A physical exam may show problems with reflexes or a positive Babinski reflex.
The following tests may be done:
Bone marrow biopsy is done only when the diagnosis is not clear.
Treatment depends on the cause of B12 deficiency anemia.
Many people may need these shots once a month for the rest of their life. The shots may no longer be needed after Crohn's disease, celiac disease, or alcoholism is properly treated.
Treatment for this form of anemia is usually effective.
Any damage to nerves may be permanent, especially if treatment is not started within 6 months of when the symptoms begin.
Vitamin B12 affects cells that form the outer surface of the body and line inner passageways (epithelial cells). Therefore, a lack of B12 may cause a falsely abnormal Pap smear.
Call your health care provider if you have any of the symptoms of anemia.
You can prevent anemia caused by a lack of vitamin B12 by following a well-balanced diet. Vitamin B12 injections can prevent anemia after surgeries known to cause vitamin B12 deficiency. Early diagnosis and prompt treatment can limit the severity and complications of this anemia.
Antony AC. Megaloblastic anemias. In: Hoffman R, Benz Ej, Shattil SS, et al., eds. Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone;2008:chap 39.
Kaferle J, Strzoda CE. Evaluation of macrocytosis. Am Fam Physician. 2009;79:203-208.
Reviewed by: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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