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Things to know about pernicious anemia and vitamin B12 deficiencyPernicious anemia is a deficiency in red blood cells caused by a lack of vitamin B12 in the blood.
Pernicious anemia is a condition in which a peron's red blood cell count is low because of a vitamin B12 deficiency. Before doctors learned that pernicious anemia could be treated with vitamin B12, many people died from the condition. Pernicious anemia causes a variety of symptoms and signs, for example:
See a picture of pernicious anemia and read more about the condition » What is pernicious anemia?Picture of normal red blood cells Anemia is a condition in which the body does not have a sufficient number of red blood cells or hemoglobin. Hemoglobin is present within red blood cells and is important for carrying oxygen to all tissues of the body. In males, anemia is typically defined as a hemoglobin level of less than 13.5 gram/100ml, while in women, a hemoglobin level of less than 12.0 gram/100ml is considered indicative of anemia. These definitions may vary slightly depending on the source and the laboratory reference used. Pernicious is a term that means destructive, injurious or deadly. Anemia can result from disruptions in the production of red blood cells or hemoglobin as well as from increased destruction of red blood cells or loss of blood. Pernicious anemia is a disease where large, immature, nucleated cells (megaloblasts, which are forerunners of red blood cells) circulate in the blood, and do not function as blood cells; it is a disease caused by impaired uptake of vitamin B-12 due to the lack of intrinsic factor (IF) in the gastric mucosa. It was termed "pernicious" because before it was learned that vitamin B-12 could treat anemia, most people that developed the disease died from it. Pernicious anemia is due to an inability to absorb vitamin B-12 (also known as cobalamin or Cbl) from the gastrointestinal tract. Humans get vitamin B-12 from animal products; both meat and dairy products are dietary sources of vitamin B-12. The body is able to store vitamin B-12 for a long time, so inadequate dietary intake must persist for years before a true deficiency of vitamin B-12 is reached. Therefore, the symptoms of pernicious anemia usually do not appear for years. While pernicious anemia is most commonly diagnosed in adults with an average age of 60, a rare, congenital (inborn) type of pernicious anemia has been described. As with other causes of anemia, symptoms related to the decreased oxygen-carrying capacity of the blood can include tiredness and shortness of breath. Vitamin B-12 deficiency also interferes with the function of the nervous system, and symptoms due to nervous system damage may be apparent even before the anemia is discovered. Pernicious anemia is more common in Caucasian persons of northern European ancestry than in other racial groups. Pernicious anemia also is termed Biermer's or Addison's anemia. See a picture of pernicious anemia and other conditions See Images
What is megaloblastic anemia?
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 also can be caused by other diseases of the bone marrow and can be a side effect of some cancer chemotherapy drugs. What causes pernicious anemia?
Pernicious anemia is considered 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 factors 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).
Is pernicious anemia the same as vitamin B-12 deficiency anemia?No, pernicious anemia is one form of vitamin B-12 deficiency that results from the autoimmune process described previously. However, other causes of vitamin B-12 deficiency also can produce the same signs and symptoms as pernicious anemia. Other potential causes of vitamin B-12 deficiency include
What are the symptoms of vitamin B-12 deficiency/pernicious anemia?
As discussed previously, true pernicious anemia results from an autoimmune condition that impairs the absorption of dietary vitamin B-12, resulting in vitamin B-12 deficiency. Vitamin B-12 deficiency of any cause, including pernicious anemia, will result in anemia and neurologic symptoms. Because the body has large stores of vitamin B-12, a deficiency takes many years to establish. Vitamin B-12 deficiency affects the nervous system, leading to a variety of symptoms. Sometimes, these may be apparent before symptoms related to the anemia. Neurological symptoms vary and may be nonspecific (meaning that these are symptoms that can be caused by a number of different conditions).
Both sides of the body are usually affected, and the legs are typically more affected than the arms. A severe deficiency can result in more serious neurological symptoms, including Symptoms of anemia are due to the reduced oxygen-carrying capacity of the blood. Shortness of breath, fatigue, dizziness and pale skin can all occur with anemia. In anemia, the heart is placed under stress since it has to work harder to deliver enough oxygen to body tissues. This can result in heart murmurs, fast heartbeats, arrhythmias, an enlarged heart (cardiomegaly), or even heart failure. It is important to note that not all people who have vitamin B-12 deficiency and neurological symptoms also will have anemia. A deficiency of vitamin B-12 also can alter the surface of the tongue, making it appear shiny or smooth. Finally, sometimes pernicious anemia is diagnosed in a patient with no symptoms. In these cases, it is usually found incidentally when blood tests are ordered for another reason. See Answer
What kinds of doctors treat pernicious anemia?Pernicious anemia may be treated by internal or family medicine specialists as well as specialists in disorders of the blood (hematologists). How is pernicious anemia/vitamin B-12 deficiency diagnosed?The first step is always a thorough history and physical examination by a health care practitioner. The results of this examination are used to help direct further testing. A number of laboratory tests are available that can help diagnose pernicious anemia as well as other causes of vitamin B-12 deficiency. These tests include:
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What is the treatment for pernicious anemia and vitamin B-12 deficiency?
The symptoms of pernicious anemia and vitamin B-12 deficiency can be treated by replenishing the vitamin B-12 supply in the body. If a condition other than pernicious anemia is responsible for vitamin B-12 deficiency, the treatment also must be directed at the underlying condition. Symptoms of vitamin B-12 deficiency may be improved after just a few days of medical treatment. Vitamin B-12 is typically given as an intramuscular injection (shot). An injection of 1000 micrograms (1 mg) of vitamin B-12 is generally given every day for one week, followed by 1 mg every week for four weeks, and then 1 mg every month thereafter. Alternative treatments for pernicious anemia include
Can pernicious anemia/vitamin B-12 deficiency be prevented?The autoimmune process that causes pernicious anemia cannot be prevented. Vitamin B-12 deficiency that is caused by conditions such as other gastrointestinal diseases and gastrointestinal surgery is preventable only to the extent that these causative conditions themselves are preventable. Vitamin B-12 is derived from animal (for example, meat, fish, poultry, and milk) sources, but vitamin B-12 deficiency in vegetarians or vegans can be prevented by the use of oral vitamin B-12 supplements.
What is the prognosis for pernicious anemia/vitamin B-12 deficiency? Can it be cured?If untreated, the neurological complications of pernicious anemia can be permanent and end in death, but pernicious anemia is easily and effectively treated by the administration of vitamin B-12. Life-long treatment is required. People with pernicious anemia have a slightly increased risk of stomach cancer when compared to the normal population. The incidence of stomach cancer in people with pernicious anemia is 2-3 times higher than in the general population of the same age. See Slideshow
Medically Reviewed on 5/24/2022 References eMedicine.com, "Pernicious anemia." |