Anemia – B12 deficiency

Alternative Names

Macrocytic anemia

Definition of Anemia – B12 deficiency

Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues.

Causes, incidence, and risk factors

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


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

Signs and tests

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


Treatment depends on the cause of B12 deficiency anemia.

Expectations (prognosis)

Treatment for this form of anemia is usually effective.


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. – 1/31/2010

Megaloblastic anemia - view of red blood cells

ADAM Medical Encyclopedia

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