MedlinePlus Medical Encyclopedia: Anemia

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Anemia - B12 deficiency

Contents of this page:
Illustrations Alternative names Definition Causes, incidence, and risk factors Symptoms Signs and tests	Treatment Expectations (prognosis) Complications Calling your health care provider Prevention

Illustrations

Megaloblastic anemia - view of red blood cells

Alternative names Return to top

Macrocytic anemia

Definition Return to top

Anemia is a drop in the number of red blood cells. This can be caused by a lack of vitamin B12.

Causes, incidence, and risk factors Return to top

Vitamin B12 is essential for normal nervous system function and blood cell production. The main sources of vitamin B12 include meat, eggs, and dairy products. For vitamin B12 to be absorbed by the body, it must bind to intrinsic factor, a protein secreted by cells in the stomach.

Causes of vitamin B12 deficiency include:

A diet low in vitamin B12 (for example, a strict vegetarian diet excluding all meat, fish, dairy products, and eggs)
Chronic alcoholism
Abdominal or intestinal surgery that affects intrinsic factor production or absorption
Crohn's disease
Intestinal malabsorption disorders
Fish tape worm
Pernicious anemia, which is caused by a lack of intrinsic factor

The risk factors are related to the causes.

Symptoms Return to top

Loss of appetite
Diarrhea
Numbness and tingling of hands and feet
Paleness
Shortness of breath
Fatigue
Weakness
Sore mouth and tongue
Confusion or change in mental status in severe or advanced cases

Signs and tests Return to top

A physical evaluation of the patient's neurological signs may show depressed deep tendon reflexes, decreased position sense, decreased vibration sense, or positive Babinski reflex. Other signs and tests include the following:

CBC results show low hematocrit with an elevated MCV
Bone marrow examination
Elevated LDH
Below-normal vitamin B12 level
Schilling test (to determine where the deficiency in B12 absorption lies).

Treatment Return to top

Treatment depends on the cause of the anemia:

Pernicious anemia requires lifelong therapy with vitamin B12 injections.
Anemia caused by a lack of vitamin B12 can be corrected by vitamin pills combined with a more balanced diet. It may be treated initially with vitamin B12 injections.
Anemia caused by malabsorption is treated with vitamin B12 injections until the condition improves.

Expectations (prognosis) Return to top

Treatment for this form of anemia is usually effective.

Complications Return to top

The signs and symptoms related to the central nervous system may be irreversible if treatment is not begun within 6 months of when these symptoms begin.
Vitamin B12 affects epithelial cells (cells that form the outer surface of the body and line inner passageways). Therefore, a a lack of B12 may cause a false positive Pap smear.

Calling your health care provider Return to top

Call your health care provider if you have any of the symptoms of anemia.

Prevention Return to top

Anemia caused by a lack of vitamin B12 can be prevented through a well-balanced diet. Preventative use of vitamin B12 injections can prevent anemia after surgeries known to cause vitamin B12 deficiency. Early diagnosis and prompt treatment can limit the severity of this anemia as well as the neurologic complications.

Update Date: 6/5/2003

Updated by: Ezra E. W. Cohen, M.D., Section of Hematology/Oncology, Department of Medicine, The University of Chicago, Chicago, IL. Review provided by VeriMed Healthcare Network.

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