Approximately 1 out of 77 people in the united states of America suffer from Anemia. And as of 2004, an estimate of over 76 million people worldwide suffer from this ailment. What actually causes Anemia?
For an better overview of the causes, Anemia should be classified. The basic cause of anemia is either an increased loss or destruction of red blood cells or an impaired or decreased rate of production. An etiologic classification is based on the various conditions leading to either of these results.
Blood loss
Acute or chronic hemorrhage results in loss of plasma and all formed elements of the blood. After acute hemorrhage, the body replaces plasma within 1 to 3 days, maintaining blood volume. However, this results in a low concentration of rd blood cells, which are gradually replaced within 3 to 4 weeks. During this period there is usually a normocytic (normal size), normochromic (normal color) anemia, and there are sufficient iron sotries for hemoglobin synthesis.
In chronic blood loss, the actual number of red blood cells may be normal because of continual replacement. However, insufficient iron is available to form hemoglobin as quickly as it is lost. As a result, erythrocytes are usually small in size (microcytic and pale in color (hypochromic).
Excessive destruction
Excessive destruction or hemolysis of erythrocytes can occur from a variety of causes. One of the most common is a result of defect within the red blood cell (intracorpuscular) that shortens the life span of the cell so that production cannot keep pace with destruction. Sickle cell anemia and thalassemia, have decreased erythrocyte life spans because of a defect in hemoglobin synthesis.
Extra-corpular factors are those conditions that cause hemolysis in otherwise normal red blood cells. A classic example is erythroblastosis fetalis. Other causes can be toxic drugs, transfusion reactions, burns, poisonings (such as from lead), infections such as malaria, and splenic sequestration (hypersplenism).
Impaired or decreased production
Impaired or decreased production of red blood cells can occur as a result of either bone marrow failure or deficiency of essential nutrients. Bone marrow failure may be caused by
• Replacement of bone marrow by fibrosis or by neoplastic cells, such as in leukemia,
• Depression of marrow activity from irradiation, chemicals or drugs, or
• Interference with bone marrow activity from other systemic diseases, such as severe infection, chronic renal disease, widespread malignancy (without marrow infiltration), collage disease, or hypothyroidism.
The reason for various systemic disorders affecting erythrocyte production varies according to the condition. For example, in severe chronic infection there is evidence that depression of erythropoiesis is caused by a defect in the conversion of proteoporphyrin into hemoglobin. In addition, there is some degree of hemolysis, although the exact mechanism is not known.
The most common childhood anemia is a result of deficient iron supply, besides iron as an essential component of hemoglobin synthesis, red blood cell production is dependent on amino acids, vitamins B6, B9 and C, folic, copper and possibly cobalt. Chronic malnutrition results in anemia as a result of generalized protein. Mineral and vitamin deficiencies.
Pernicious anemia develops when the gastric mucosa fails to secrete sufficient amounts of intrinsic factor, which is essential for absorption of vitamin B12. This type of anemia is common in the elderly as a result of physiologically decreased gastric secretions. Deprived of vitamin B12, the bone marrow produces fewer but larger (macrocytic) red blood cells. The erythrocytes are usually immature and because of their extremely fragile cell membranes, are more rapidly destroyed during circulation.
Classification based on morphology
A second classification has been made that is based on the morphologic changes within the red blood cell. The major categories
1. normocytic
2. microcytic
3. macrocytic
In addition, each category may be subdivided according to the amount of hemoglobin in the cell, since hemoglobin gives the cell its characteristic red color, the usual classifications are
• normochromic
• microchromic
Classification based on Hb level
Stage I
• mild stage
• Hemoglobin level is 110-90g/l
• Erythrocyte count is 3.5-3.0×10^12/l
Stage II
• Moderate stage
• Hemoglobin level is 90-70g/l
• Erythrocyte count is 3.0-2.5×10^12/l
Stage III
• Severe stage
• Hemoglobin level is Laboratory criteria
Laboratory criteria of anemia in neonatal period are
• 0-14 days – Hemoglobin level is less than 145g/l
• 15-28days- Hemoglobin level is less than 120g/l
Tags: anemia, Blood Volume, Cause Of Anemia, Chronic Blood Loss, Hemoglobin Synthesis, Hemolysis, Toxic Drugs, Transfusion Reactions
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