Pernicious anemia refers to a type of autoimmune anemia. Antibodies are directed against intrinsic factor or parietal cells which produce intrinsic factor. Intrinsic factor is required for vitamin B12 absorption, so impaired absorption of vitamin B12 can result.
Blood testing typically shows a macrocytic anemia, and low levels of serum vitamin B12. A Schilling test can then be used to distinguish between pernicious anemia, vitamin B12 malabsorption, and vitamin B12 deficiency. Approximately 90% of individuals with pernicious anemia have antibodies for parietal cells, however only 50% of individuals with these antibodies have the disease.
The term 'pernicious anemia' is sometimes used more loosely to include non-autoimmune causes of vitamin B12 deficiency.
The treatment for pernicious anemia was first devised by William Murphy who bled dogs to make them anemic and then fed them various substances to see what (if anything) would make them healthy again. He discovered that ingesting large amounts of liver seemed to cure the disease. George Minot and George Whipple then set about to chemically isolate the curative substance and ultimately were able to isolate the vitamin B12 from the liver. For this, all three shared the 1934 Nobel Prize in Medicine. As a result, pernicious anemia is now treated with either vitamin B12 injections (hydroxocobalamin or cyanocobalamin), or large oral doses of vitamin B12, typically between 2 and 4 mg daily.
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