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Anemia - B12 deficiency

MedlinePlus Topics

Anemia

Images

Megaloblastic anemia - view of red blood cells Megaloblastic anemia -
view of red blood cells

Read More

Central nervous system Chronic Crohn's disease Intrinsic factor
Malabsorption Pap smear Pernicious anemia Vitamin B12

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.

See also:

Megaloblastic anemia

Pernicious anemia

Causes

Your body needs vitamin B12 to make red blood cells. In order to
provide vitamin B12 to your cells:

You must eat enough foods that contain vitamin B12, such as meat,
 poultry, shellfish, eggs, and dairy products.

Your body must absorb enough vitamin B12. Your body uses a special
 protein, called intrinsic factor, released by cells in the
 stomach. The combination of vitamin B12 attached to intrinsic
 factor is absorbed in the last part of the small intestine.

A lack of vitamin B12 in the diet may be due to:

Eating a vegetarian diet

Poor diet in infancy

Poor nutrition during pregnancy

A number of problems can make it difficult for your body to absorb
enough vitamin B12:

Chronic alcoholism

Crohn's disease, celiac disease, infection with the fish tapeworm,
 or other problems that make it difficult for your body to digest
 foods

Pernicious anemia, which occurs when your body destroys cells that
 make intrinsic factor. Intrinsic factor is needed to absorb
 vitamin B12.

Surgeries that remove certain parts of your stomach or small
 intestine, such as some weight-loss surgeries

Taking antacids and other heartburn medicines for a long period of
 time

Symptoms

People with mild anemia may have no symptoms, or symptoms may be very
mild.

More typical symptoms of vitamin B12 deficiency anemia include:

Diarrhea or constipation

Fatigue, lack of energy, or light-headedness when standing up or
 with exertion

Loss of appetite

Pale skin

Problems concentrating

Shortness of breath, mostly during exercise

Swollen, red tongue or bleeding gums

Symptoms from nerve damage caused by vitamin B12 deficiency that has
been present for a longer time include:

Confusion or change in mental status (dementia) in severe cases

Depression

Loss of balance

Numbness and tingling of hands and feet

Exams and Tests

A physical exam may show problems with reflexes or a positive Babinski
reflex.

The following tests may be done:

CBC

Reticulocyte count

Schilling test (if pernicious anemia is suspected)

Serum LDH

Serum vitamin B12 level and serum folate levels

Esophagogastroduodenoscopy (EGD) to examine the stomach, or
enteroscopy to examine the small intestine may be done.

Bone marrow biopsy is done only when the diagnosis is not clear.

Treatment

Treatment depends on the cause of B12 deficiency anemia.

Pernicious anemia requires lifelong vitamin B12 replacement, most
 often using injections. Some patients can get enough
 supplementation with high-dose tablets of oral vitamin B12.

People with anemia due to a lack of dietary vitamin B12 may be
 told to take vitamin supplements and follow a more balanced diet.
 Treatment may start with vitamin B12 injections.

Anemia caused by poor digestion and absorption is treated with
 vitamin B12 injections until the condition improves. These shots
 are given every day and then every week at first, and then every
 month.

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.

Outlook (Prognosis)

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.

Possible Complications

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.

When to Contact a Medical Professional

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

Prevention

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.

Alternative Names

Macrocytic anemia

References

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.

Update Date: 1/31/2010

Updated 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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Page last updated: 23 February 2010

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