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Medical Author:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Medical Editor:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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In this Article

• What is pernicious anemia?
• What is megaloblastic anemia?
• What causes pernicious anemia?
• Is pernicious anemia the same as vitamin B-12 deficiency anemia?
• What are the symptoms of vitamin B-12 deficiency/pernicious anemia?
• How is pernicious anemia/vitamin B-12 deficiency diagnosed?
• What is the treatment for pernicious anemia/vitamin B-12 deficiency?
• Can pernicious anemia/ vitamin B-12 deficiency be prevented?
• What is the prognosis for pernicious anemia/ vitamin B-12 deficiency?
• Pernicious Anemia At A Glance
• Patient Comments: Pernicious Anemia - Share Your Experience
• Patient Comments: Pernicious Anemia - Symptoms
• Patient Comments: Pernicious Anemia - Treatments
• Find a local Hematologist in your town
• Pernicious Anemia Index

Sometimes, anemias are subclassified based upon the size and microscopic appearance of the red blood cells. In this regard, pernicious anemia is a form of megaloblastic anemia. Megaloblastic anemia refers to an abnormally large type of red blood cell (megaloblast). Megaloblasts are produced in the bone marrow when vitamin B-12 or folic acid levels are low. Megaloblastic anemia can also be caused by other disease of the bone marrow and can be a side effect of some cancer chemotherapy drugs.

Pernicious anemia is considered to be an autoimmune disease, in which the body's own immune system mistakenly damages its own tissues. It is believed that the decreased absorption of vitamin B-12 from the gastrointestinal tract in pernicious anemia results from the presence of an autoantibody against intrinsic factor (IF), a protein made in the stomach that is necessary for the absorption of vitamin B-12. Normally, vitamin B-12 binds to intrinsic factor in the stomach, and this facilitates its absorption by the small intestine further along in the digestive process. Along with the autoimmune process that attacks the IF protein and lowers IF levels in stomach secretions, another autoimmune reaction against the stomach lining cells also occurs, resulting in a form of inflammation known as chronic atrophic gastritis.

Pernicious anemia is sometimes associated with other autoimmune diseases such as Graves' disease, Hashimoto's thyroiditis and vitiligo (depigmentation or blanching of skin areas).