pernicious anemia

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Related to pernicious anemia: iron deficiency anemia, aplastic anemia


anemia (ənēˈmēə), condition in which the concentration of hemoglobin in the circulating blood is below normal. Such a condition is caused by a deficient number of erythrocytes (red blood cells), an abnormally low level of hemoglobin in the individual cells, or both these conditions simultaneously. Regardless of the cause, all types of anemia cause similar signs and symptoms because of the blood's reduced capacity to carry oxygen. These symptoms include pallor of the skin and mucous membranes, weakness, dizziness, easy fatigability, and drowsiness. Severe cases show difficulty in breathing, heart abnormalities, and digestive complaints.

One of the most common anemias, iron-deficiency anemia, is caused by insufficient iron, an element essential for the formation of hemoglobin in the erythrocytes. In most adults (except pregnant women) the cause is chronic blood loss rather than insufficient iron in the diet, and, therefore, the treatment includes locating the source of abnormal bleeding in addition to the administration of iron.

Pernicious anemia causes an increased production of erythrocytes that are structurally abnormal and have attenuated life spans. This condition rarely occurs before age 35 and is inherited, being more prevalent among persons of Scandinavian, Irish, and English extraction. It is caused by the inability of the body to absorb vitamin B12 (which is essential for the maturation of erythrocytes).

There are several conditions that cause the destruction of erythrocytes, thereby producing anemia. Allergic-type reactions to bacterial toxins and various chemical agents, among them sulfonamides and benzene, can cause hemolysis, which requires emergency treatment. In addition, there are unusual situations in which the body produces antibodies against its own erythrocytes; the mechanism triggering such reactions remains obscure.

There are several inherited anemias that are more common among dark-skinned people. Sickle cell disease is inherited as a recessive trait almost exclusively among blacks; the condition is characterized by a chemical abnormality of the hemoglobin molecule that causes the erythrocytes to be misshapen. In 1957 Vernon Ingram determined the amino acid sequence of hemoglobin, and found the beta-globins (which is one of the two polypeptide chain types) that are found in the tetrameric (four-chain) hemoglobin protein. In sickle cell disease a single mutation produces the amino acid valine instead of glutamic acid in one of the protein chain types that make up the hemoglobin molecule.

In thalassemia major (Cooley's anemia), which is the most serious of the hereditary anemias among people of Mediterranean, Middle Eastern, and S Chinese ancestry, the erythrocytes are abnormally shaped. Symptoms include enlarged liver and spleen and jaundice. Thalassemia major usually causes death before adulthood is reached.

Any disease or injury to the bone marrow can cause anemia, since that tissue is the site of erythrocyte synthesis. Bone marrow destruction can also be caused by irradiation, disease, or various chemical agents. In cases of renal dysfunction, the severity of the associated anemia correlates highly with the extent of the dysfunction; it is treated with genetically engineered erythropoietin.

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pernicious anemia

[pər′nish·əs ə′nēm·ē·ə]
A megaloblastic macrocytic anemia resulting from lack of vitamin B12, secondary to gastric atrophy and loss of intrinsic factor necessary for vitamin B12 absorption, and accompanied by degeneration of the posterior and lateral columns of the spinal cord.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Role of Helicobacter on infection in pernicious anemia 2000 Dec;32(9):756-62.
In one study, 64 patients receiving 500 mcg or 1,000 meg of [B.sub.12] orally daily for pernicious anemia all had normal serum [B.sub.12] levels, normalization of hemoglobin levels, and no neurologic complications at follow-up through 5 years.
Pernicious anemia has also been reported among Indians, though rarely: most of the publications describe isolated cases of them.
Autoimmune atrophic gastritis is the most frequent cause of pernicious anemia in temperate climates.
In the western countries, pernicious anemia is the most common form of vitamin B12 deficiency.
If an image of an elderly patient with pernicious anemia is the first thing that comes to mind when you think of [B.sub.12] deficiency, take note: That image could obfuscate a more common case of [B.sub.12] deficiency--one caused by food-[B.sub.12] malabsorption.
AGPA are a marker of autoimmune gastritis whereas intrinsic factor antibodies are associated with pernicious anemia. The progression of chronic atrophic gastritis to pernicious anemia may occur over time and may take 20 to 30 years before this may happen.
In particular, patients with pernicious anemia, possibly the commonest type of cobalamin deficiency in developed countries, require either massive doses of oral vitamin [B.sub.12] or parenteral replacement therapy (3-5).
and Canadian authorities are hesitant to add more folic acid to flour is because too much folic acid may camouflage vitamin [B.sub.12] deficiency (pernicious anemia), which largely affects older people, not pregnant women.
Robert Stokstad, the "father" of folic acid research, belonged to one of two in teams in the early 1940s vying to identify the dietary factor responsible for pernicious anemia. Dr.
We also know that mostly the elderly are vulnerable to pernicious anemia, the rare [B.sub.12] deficiency anemia.
Minot and Murphy had demonstrated that there was a dietary factor in liver that reversed the onslaught of pernicious anemia (see 1926).