Anemia is a condition characterized by an insufficient number of properly functioning red blood cells. There are several types of anemia, and treatment options vary with the type and severity of the disorder. Anemia may be due to the body’s inability to produce or renew adequate red blood cells, or may be due to abnormal destruction of these cells by the body. More severe forms of anemia involve other medical conditions and complications and can be lethal, while milder forms are often treated fairly easily and have symptoms that may go unnoticed for weeks or months. Red blood cells are the cells that transport oxygen needed for basic biological processes throughout the body. An iron-rich protein called hemoglobin that resides in red blood cells is responsible for ensuring the successful transport of oxygen, and when there is not a sufficient number of red blood cells in the body, or when red blood cells or hemoglobin are abnormal or damaged, cells are deprived of oxygen. The main causes of anemia include serious diseases, dietary deficiencies, blood loss, genetic defects or disease, and medication.
One common form of anemia is nutritional anemia, which develops when a person's diet does not include sufficient iron, folate, or vitamin B12, all necessary for the formation of hemoglobin. Frequently, children, teens, and the elderly are more susceptible to this type of anemia, which can then be complicated by underlying medical conditions. Metabolic conditions which prevent nutrient absorption can also be to blame for nutritional anemia. This is seen as a deficiency in folate or vitamin B12 in alcoholics, for example.
Other types of anemia can be caused by chronic kidney disease, diabetes, heart disease, cancer, and autoimmune diseases such as rheumatoid arthritis and HIV. These can interfere with the body's production, maintenance, and renewal of functioning red blood cells, either because of primary effects of the disease or the effects of medication (such as chemotherapy for cancer and AZT for AIDS/HIV) used to treat the disease. The blood loss of major surgery can also be a cause of anemia, as the body tries to produce replacement blood cells and heal from an invasive procedure simultaneously. Some diseases, such as leukemia, involve the bone marrow, where blood cells are produced, and interfere with the creation of red blood cells by disrupting normal bone marrow function. Others diseases actually destroy red blood cells after they are made.
Several types of anemia are caused by genetic mutations, which are often inherited from a parent who caries the defective gene. These types of anemia include thalassemia, sickle cell anemia, aplastic anemia, and myelodysplasia. In thalassemia, patients lack the ability to produce normal hemoglobin, and suffer severe fatigue, stunted growth, bone deformities, and other severe medical problems from a very young age; many patients with this form of anemia do not live into adulthood. This defect is usually found in patients of Mediterranean descent. Patients suffering from sickle cell anemia have an excess of misshapen red blood cells (they are crescent-shaped, hence the "sickle" in the disease's name) which cannot carry oxygen appropriately, and build up in blood vessels, blocking circulation with painful and dangerous results. Black patients are most commonly affected by this disease. In aplastic anemia, the bone marrow fails to produce sufficient blood cells. In myelodysplasia, the bone marrow fails to produce normal blood cells, as many of the cells that are produced do not function properly.
