Pernicious anemia is a decrease in the red blood cells in humans because of the patient’s inability to absorb vitamin B12 from the gastrointestinal tract. The vitamin is water soluble and is necessary for the development of red blood cells. In general, water soluble vitamins quickly exit the body through the urine, but vitamin B12 has the capacity to store in the liver for several years.
Cobalamin and the blood
Vitamin B12, or cobalamin, participates in several biochemical pathways in humans. Adults require 2.4 micrograms of it each day. When deficiency of vitamin B12 occurs, the red blood cells may become larger than normal; hence, these patients have macrocytic or megaloblastic anemia. In medicine, “macro” and “megalo” mean large, and “cyte” and “blast” refer to the cell.
The diagnostic dilemma is that other medical conditions may cause macrocytosis or large red cells, and the physician has to treat the correct source of the blood abnormality. For example, folic acid deficiency will cause macrocytosis. This especially occurs in people who consume excessive amounts of alcohol, and they require supplementation with folic acid and other vitamins.
If the macrocytosis is really due to vitamin B12 deficiency rather than folic acid, it will pose a problem should the patient receive only folic acid to remedy the situation. Folic acid therapy will resolve the blood abnormality, but it will not correct the deficiency of vitamin B12. In other words, treatment with folic acid will mask the microscopic picture of the blood while the deficiency of vitamin B12 remains.
Various medications and other medical conditions will cause macrocytosis and folic acid deficiency.
As beef liver is one of several foods which contain a lot of vitamin B12, it is no surprise that a half century ago the treatment for pernicious anemia was to recommend that the patient consume raw animal liver.
Signs and symptoms
Symptoms of this disease are fatigue, lack of energy, loss of appetite, pale skin, diarrhea or constipation, swollen red tongue, bleeding gums, and shortness of breath. If pernicious anemia continues without treatment for several years, there may be nerve damage, mental confusion, dementia, depression, loss of balance, numbness and tingling of the hands and feet. They may also experience hallucinations, loss of vision, and these patients can become violent.
If a woman with pernicious anemia does not receive treatment and she visits a physician to have a Pap smear, that test may be false positive.
Patients with pernicious anemia must tell their physician about all medications they take whether over-the-counter or otherwise as some of these treatments will affect blood levels of vitamin B12. The treatment for pernicious anemia is a well-balanced diet as well as lifelong injections of that vitamin. There are also preparations of vitamin B12 which the patient can take by mouth or through the nose.
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.
National Institutes of Health. Medline Plus. (2008). Pernicious anemia. Retrieved January 25,
National Institutes of Health. Office of Dietary Supplements. (2010). Vitamin B12. Retrieved
January 25, 2011.