Introduction
Anemia is an abnormal reduction in red blood cells.
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| This phomicrograph shows normal red blood cells (RBCs) as seen in the microscope after staining. |
Anemia is a great problem globally, and worse in developing countries, but it is by no means absent in industrialized nations. An estimated 3.4 million Americans suffer from anemia. Anemia is not a single disease but a condition, like fever, with many possible causes and many forms. Causes of anemia include nutritional deficiencies, inherited genetic defects, medication-related side effects, and chronic disease. It can also occur because of blood loss from injury or internal bleeding, the destruction of red blood cells, or insufficient red blood cell production. The condition may be temporary or long term, and can manifest in mild or severe forms.
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As it is impossible to discuss all types of anemia, this report focuses on three of the most common forms:
- Iron deficiency anemia
- Anemia of chronic disease (ACD)
- Megaloblastic anemia (caused by deficiencies in the B vitamins folate, vitamin B12, or both)
Some less common causes and types of anemia are included in a table in this report.
Blood
Blood has two major components:
- Plasma is a clear yellow liquid that contains proteins, nutrients, hormones, electrolytes, and other substances. It constitutes about 55% of blood.
- White and red blood cells and platelets make up the balance of blood. The white cells are the infection fighters for the body, and platelets are necessary for blood clotting. The important factors in anemia, however, are red blood cells.
Red blood cells (RBCs), also known as erythrocytes, carry oxygen throughout the body to nourish tissues and sustain life. Red blood cells are the most abundant cells in our bodies; men have about 5,200,000 and women about 4,700,000 per cubic millimeter of blood.
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