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Anemia, also spelled anaemia, is usually defined as a decrease in the amount of red blood cells (RBCs) or hemoglobin in the blood.〔(【引用サイトリンク】url=http://www.merriam-webster.com/dictionary/anemia )〕 It can also be defined as a lowered ability of the blood to carry oxygen. When anemia comes on slowly the symptoms are often vague and may include: feeling tired, weakness, shortness of breath or a poor ability to exercise. Anemia that comes on quickly often has greater symptoms which may include: confusion, feeling like one is going to pass out, and increased thirst. Anemia must be significant before a person becomes noticeably pale. Additional symptoms may occur depending on the underlying cause. There are three main types of anemia: that due to blood loss, that due to decreased red blood cell production, and that due to increased red blood cell breakdown. Causes of blood loss include trauma and gastrointestinal bleeding, among others. Causes of decreased production include iron deficiency, a lack of vitamin B12, thalassemia and a number of neoplasms of the bone marrow among others. Causes of increased breakdown include a number of genetic conditions such as sickle cell anemia, infections like malaria and some autoimmune diseases among others. It can also be classified based on the size of red blood cells and amount of hemoglobin in each cell. If the cells are small it is microcytic anemia, if they are large it is macrocytic anemia and if they are normal sized it is normocytic anemia. Diagnosis in men is based on a hemoglobin of less than 130 to 140 g/L (13 to 14 g/dL), while in women it must be less than 120 to 130 g/L (12 to 13 g/dL).〔 Further testing is then required to determine the cause.〔 Certain groups of individuals, such as pregnant women, benefit from the use of iron pills for prevention.〔 Dietary supplementation, without determining the specific cause, is not recommended. The use of blood transfusions is typically based on a person's signs and symptoms.〔 In those without symptoms they are not recommended unless hemoglobin levels are less than 60 to 80 g/L (6 to 8 g/dL).〔〔 These recommendations may also apply to some people with acute bleeding.〔 Erythropoiesis-stimulating medications are only recommended in those with severe anemia. Anemia is the most common disorder of the blood with it affecting about a quarter of people globally.〔 Iron-deficiency anemia affects nearly 1 billion. In 2013 anemia due to iron deficiency resulted in about 183,000 deaths – down from 213,000 deaths in 1990. It is more common in females than males,〔 among children, during pregnancy, and in the elderly.〔 Anemia increases costs of medical care and lowers a person's productivity through a decreased ability to work.〔 The name is derived from ', meaning "lack of blood", from ἀν- ''an-'', "not" + αἷμα ''haima'', "blood".〔(【引用サイトリンク】url=http://dictionary.reference.com/browse/anaemia )〕 ==Signs and symptoms== Anemia goes undetected in many people, and symptoms can be minor or vague. The signs and symptoms can be related to the underlying cause or the anemia itself. Most commonly, people with anemia report feelings of weakness, or fatigue, general malaise, and sometimes poor concentration. They may also report dyspnea (shortness of breath) on exertion. In very severe anemia, the body may compensate for the lack of oxygen-carrying capability of the blood by increasing cardiac output. The patient may have symptoms related to this, such as palpitations, angina (if pre-existing heart disease is present), intermittent claudication of the legs, and symptoms of heart failure. On examination, the signs exhibited may include pallor (pale skin, lining mucosa, conjunctiva and nail beds), but this is not a reliable sign. There may be signs of specific causes of anemia, e.g., koilonychia (in iron deficiency), jaundice (when anemia results from abnormal break down of red blood cells — in hemolytic anemia), bone deformities (found in thalassemia major) or leg ulcers (seen in sickle-cell disease). In severe anemia, there may be signs of a hyperdynamic circulation: tachycardia (a fast heart rate), bounding pulse, flow murmurs, and cardiac ventricular hypertrophy (enlargement). There may be signs of heart failure. Pica, the consumption of non-food items such as ice, but also paper, wax, or grass, and even hair or dirt, may be a symptom of iron deficiency, although it occurs often in those who have normal levels of hemoglobin. Chronic anemia may result in behavioral disturbances in children as a direct result of impaired neurological development in infants, and reduced scholastic performance in children of school age. Restless legs syndrome is more common in those with iron-deficiency anemia. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「anemia」の詳細全文を読む スポンサード リンク
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