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Intrinsic factor



Intrinsic factor is a protein produced by cells in the stomach lining. It is needed for the intestines to absorb vitamin B12 efficiently.


In a disease called pernicious anemia, immune system damage to the stomach lining can cause a lack (deficiency) of intrinsic factor. Pernicious anemia causes vitamin B12 deficiency, which leads to a low red blood cell count (anemia).

Intrinsic factor deficiencies can also be caused by other reasons, such as:

  • Inherited conditions
  • Other diseases
  • Surgical removal of the stomach

Antony AC. Megaloblastic anemia. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 170.

Antony AC. Megaloblastic anemia. In: Hoffman R, Benz EJ, Shattil SS, et al., eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 39.

Review Date: 1/31/2010
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and 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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