Vitamin B12 deficiency anemia

Definition

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.

Alternative Names

Megaloblastic macrocytic anemia

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 if you've had a surgery known to cause vitamin B12 deficiency.

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

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.

Means RT. Approach to the anemias. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 149.

Perez DL, Murray ED, Forester BP, Price BH. Depression and psychosis in neurological practice. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 10.


Review Date: 1/25/2022
Reviewed By: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. 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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