Pernicious anemia

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. more...

The term pernicious anemia is sometimes used more loosely to include non-autoimmune causes of vitamin B12 deficiency.

Diagnosis

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.

History

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.

Symptoms

Pernicious anemia may cause inflammation of the tongue (glossitis). Perncious anemia is also associated with premature greying, blue eyes, vitiligo, and blood group A.

Treatment

Treatment usually consists of an initial two week course of B12 injections every other day to cause B12 to be stored in the liver, or a longer course if the patient's B12 level is seriously low in the view of the doctor; then booster shots performed at regular intervals, usually once a month, throughout the life of the patient. Injections usually contain a reddish liquid called hydroxycobalamin or cyanocobalamin. They are given directly into the muscle, usually in the arms, to avoid going through the ileum and being destroyed.

Alternatively, B12, when given in sufficient quantity, can be absorbed orally in a pathway that does not require intrinsic factor or an ileum. Usually, this requires a dose of around 1000 to 2000 mcg. By contrast, the typical Western diet contains 5-7 mcg of B12.

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