anemia(redirected from macrocytic normochromic anemia)
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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.
Anemia is a disease of the blood that has come, in some quarters, to be associated with vampirism. Anemia is caused by a reduction of either red blood cells or hemoglobin (the oxygen-carrying pigment of the cells) relative to the other ingredients in the blood. The symptoms include a pale complexion, fatigue, and in its more extreme instances, fainting spells. All are symptoms usually associated with a vampire attack. In Bram Stoker‘s novel, Dracula (1897), during the early stages of Lucy Westenra‘s illness, Dr. John Seward hypothesized that possibly she was suffering from anemia. He later concluded that she was not suffering from the loss of red blood cells, but from the loss of whole blood. Dr. Abraham Van Helsing agreed with his friend, “I have made careful examination, but there is no functional cause. With you I agree that there has been much blood lost; it has been, but is not. But the conditions of her are in no way anemic.” (Chapter 9) Thus, the association of anemia and vampirism was dismissed.
(blood deficiency), a group of diseases characterized by a reduction in the content of hemoglobin (the oxygen-carrying pigmentation substance of the blood) in the erythrocytes, in the number of erythrocytes per unit volume of blood for a person of a given age and sex, and in the total amount of blood in the organism. Anemia causes pathological changes which result from disruption of the organism’s oxygen supply. The degree of manifestation of these features depends on the degree of anemia and on the speed of its development. The most important general symptoms of anemia are weakness, pale skin color, shortness of breath, dizziness, and a tendency to faint. Anemia is caused by three primary factors: loss of blood, impairment of blood formation, and increased destruction of blood.
Anemia associated with acute blood loss develops with wounds and gastrointestinal, pulmonary, nasal, and uterine (more rarely renal) hemorrhages. In such anemia, acute paleness, dizziness, noise in the ears, and strong thirst appear suddenly. In order to prevent a condition that threatens life, the blood flow must be stopped immediately. Frequently, surgical intervention is required; hemostatics and blood transfusions are then employed.
A frequent cause of anemia is a shortage of iron in the organism. In this case, the disease is called hypoferric anemia. Iron is included in the makeup of the hemoglobin of erythrocytes and enzymes which participate in cell respiration, and it is hardly discharged from the organism at all. An iron deficiency arises as a result of small but frequent losses of blood (as in abundant and prolonged menstruation or hemorrhage). This kind of anemia occurs especially often if chronic blood losses are combined with reduced secretion of gastric juices, which may lead to a reduction in the absorption of the iron found in food products. Hypoferric anemia often develops in children in their first year of life if the mother had a lack of iron in her body. The same form of anemia is sometimes encountered in premature babies who did not have time to receive the necessary amount of iron from the mother. Hypoferric anemia may develop during the pubescent period in young girls born of mothers with iron deficiencies: this is juvenile chlorosis (in Russian also called the pallid infirmity and early chlorosis). In addition to the general signs of anemia, the following are typical of chlorosis: hair falling out, fingernails and toenails breaking, perversion of the taste (the desire to eat chalk, tooth powder, coal, and graphite from pencils), and urinary disorders (the failure to hold urine at night and frequent calls to urinate). Hypoferric anemia is treated with various iron preparations combined with ascorbic acid. (They are absorbed best in this combination.)
There are forms of anemia in which the organism has enough iron but cannot use it fully because of reduced activity of the enzymes which form hemoglobin (pernicious anemia). Such forms of anemia are hereditary or associated with lead poisoning. Vitamin B6 has a therapeutic effect upon these forms of the disease. Lead poisoning therapy is conducted. Impairment of blood formation is observed with a deficiency of vitamin B12 in the organism—avitaminosis B12, Addison-Biermer anemia (formerly called pernicious anemia), or malignant anemia. The cause of this type of anemia is impairment of the stomach’s output of a special protein, gastric mucoprotein (Castle’s intrinsic factor), which ensures absorption of vitamin B12 in the intestine. A deficiency of vitamin B12 may also occur in the organisms of patients from whom the entire stomach has been removed in the past and in patients with helminthiasis, particularly broad tapeworm. In avitaminosis B12 the formation of ribonucleic acid (RNA) needed for cell reproduction is impaired in the organism. As a result, blood formation is impaired, the erythrocytes increase in size, and the number of them in the blood volume decreases. As a result of enlargement of the epithelial cells, the structure of the epithelium of the tongue changes: this is a symptom of the sickness. Sometimes the spinal cord is also afflicted. In 1926 it was proposed that this form of anemia be treated with raw liver; subsequently vitamin B12, the primary medicine used for Addison-Biermer anemia, was extracted from it.
Impairment of blood formation, which is manifested in perversion of the formation of the primordial cells from which erythrocytes, leukocytes, and thrombocytes form in the bone marrow, leads to the development of hypoplastic and aplastic anemia. A reduction in the number of erythrocytes, leukocytes, and thrombocytes per unit volume of blood is typical of hypoplastic anemia. Hormone drugs (glucocorticoid and male sex hormones) have a therapeutic effect, and sometimes removal of the spleen is effective. In addition, bone marrow is sometimes transplanted.
Hemolytic anemia is caused by increased hemolysis (the destruction of erythrocytes). Erythrocytes usually live about 120 days. When antibodies against the patient’s own erythrocytes appear, the life-span of the erythrocytes is significantly shortened. Rapid destruction of a large number of erythrocytes occurs; as a result of the decomposition of hemoglobin in the patient, the tissues of the organism take on a yellow pigmentation (jaundice). Immune hemolytic anemia develops; to treat it, hormone drugs (glucocorticoid hormones) are used. Sometimes acute hemolytic anemia develops in an infant during its birth; this is associated with an incompatibility between the mother’s blood and the infant’s blood. Thus, hereditary forms are common in hemolytic anemia. Their development is associated with genetic impairment of the function of the enzymes which participate in formation of the walls of the erythrocytes or in accumulating the energy necessary for their vital activity and for preserving the walls. Removing the spleen is sometimes effective in hereditary hemolytic anemia.
With a hereditary deficiency in the erythrocytes of certain enzymes (glucose-6-phosphate dehydrogenase and others), the erythrocytes lose their ability to counteract the harmful effects on vital cell processes which are caused by certain medicines, some foods, and other substances. In such patients a grave hemolytic anemia, which is frequently found among the peoples who live in Africa, the Mediterranean basin, and the southern republics of the USSR, develops after taking even small doses of acetylsalicylic acid (aspirin), streptocide, and quinine; when using certain legumes as food; and even when the pollen of these plants enters the mouth.
In the same geographic zones, hereditary anemia associated with impairment of synthesis of the protein part of hemoglobin is widespread. These forms of anemia are known as hemoglobinopathy. In certain forms of this disease the erythrocytes are shaped like sickles (sickle-cell anemia) or like ovals (target-cell anemia). Therapy for all types of anemia can be conducted only after a precise determination of the diagnosis and form of anemia.
REFERENCESKassirskii, I. A., and G. A. Alekseev. Klinicheskaia gematologiia, 3rd ed. Moscow, 1962. (Bibliography.)
Genetika ν gematologii. Leningrad, 1967.
L. I. IDEL’SON