Anemia - megaloblastic

Alternative names
Megaloblastic anemia

Megaloblastic anemia is a blood disorder characterized by anemia, with red blood cells that are larger than normal, usually resulting from a deficiency of Folic acid or of vitamin B-12.

Causes, incidence, and risk factors
Deficiencies of vitamin B-12 and Folic acid are the most common causes of megaloblastic anemia. Other causes are Leukemia, myelofibrosis, Multiple Myeloma, certain hereditary disorders, drugs that affect DNA synthesis such as Chemotherapy agents (methotrexate), alcohol, and other causes. Risk factors relate to the causes. (See also Pernicious anemia).


  • Loss of appetite  
  • diarrhea  
  • Tingling and numbness of hands and feet  
  • Pale skin color  
  • Tiredness  
  • headaches  
  • Sore mouth and tongue  
  • Change in skin color

Signs and tests
Examination of neurological signs may show abnormal reflexes, decreased position sense, and decreased vibration sense if related to vitamin B-12 deficiency.

Tests include:

  • Complete blood count (shows anemia with large red blood cells)  
  • Bone marrow examination  
  • Serum B-12  
  • Schilling test (may identify poor absorption as cause of vitamin B-12 deficiency)  
  • Serum folate

The objective of treatment is to determine the cause of the anemia, and the treatment depends upon the cause. Anemias related to vitamin deficiencies are discussed separately.

Expectations (prognosis)
The outcome is expected to be good with treatment.

Complications vary with the underlying cause.

Calling your health care provider
Call for an appointment with your health care provider if symptoms develop.

Adequate intake of vitamin B-12 and Folic acid is helpful.

Johns Hopkins patient information

Last revised: December 2, 2012
by Arthur A. Poghosian, M.D.

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