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Vitamin B12 deficiency anemia

Megaloblastic macrocytic anemia

Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. There are many types of anemia.

Vitamin B12 deficiency anemia is a low red blood cell count due to a lack (deficiency) of vitamin B12.

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Megaloblastic anemia - view of red blood cells
Hypersegmented PMN (Close-up)

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Causes

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

A lack of vitamin B12 may be due to dietary factors, including:

Certain health conditions can make it difficult for your body to absorb enough vitamin B12. They include:

Symptoms

You may not have symptoms. Symptoms may be mild.

Symptoms can include:

If you have low vitamin B12 level for a long time, you can have nerve damage. Symptoms of nerve damage include:

Exams and Tests

The health care provider will perform a physical exam. This may reveal problems with your reflexes.

Tests that may be done include:

Other procedures that may be done include:

Treatment

Treatment depends on the cause of B12 deficiency anemia.

The goal of treatment is to increase your vitamin B12 level.

Your provider will also recommend that you eat a variety of foods.

Outlook (Prognosis)

People with this type of anemia often do well with treatment.

Long-term vitamin B12 deficiency can cause nerve damage. This may be permanent if you do not start treatment within 6 months of when your symptoms begin.

Vitamin B12 deficiency anemia most often responds well to treatment. It will likely get better when the underlying cause of the deficiency is treated.

Possible Complications

A woman with a low B12 level may have a false positive Pap smear. This is because vitamin B12 deficiency affects the way certain cells (epithelial cells) in the cervix look.

When to Contact a Medical Professional

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

Prevention

You can prevent anemia caused by a lack of vitamin B12 by eating a well-balanced diet.

Shots of vitamin B12 can prevent anemia after surgeries known to cause vitamin B12 deficiency.

Early diagnosis and prompt treatment can reduce or prevent complications related to a low vitamin B12 level.

Related Information

Vitamin B12
Intrinsic factor
Chronic
Crohn disease
Malabsorption
Pernicious anemia
Central nervous system
Pap test

References

Antony AC. Megaloblastic anemias. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 39.

Bunn HF. Approach to the anemias. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 158.

Perez DL, Murray ED, Price BH. Depression and psychosis in neurological practice. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 10.

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Review Date: 1/19/2018  

Reviewed By: Richard LoCicero, MD, private practice specializing in Hematology and Medical Oncology, Longstreet Cancer Center, Gainesville, GA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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