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Iron-deficiency anemia, also spelled iron deficiency anaemia, is anemia due to not enough iron. Anemia is 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 )〕 When anemia comes on slowly, the symptoms are often vague and may include feeling tired, weakness, shortness of breath or 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. There needs to be significant anemia before a person becomes noticeably pale. There may be additional symptoms depending on the underlying cause. It is caused by insufficient dietary intake and absorption of iron, or iron loss from bleeding. Bleeding can be from a range of sources such as the intestinal, uterine or urinary tract. The most common cause of iron-deficiency anemia in children in developing countries is parasitic worms: hookworms, whipworms, and roundworms. Worms cause intestinal bleeding, which is not always noticeable in feces, and is especially damaging to growing children. Malaria, hookworms and vitamin A deficiency contribute to anemia during pregnancy in most underdeveloped countries. In women over 50 years old, the most common cause of iron-deficiency anemia is chronic gastrointestinal bleeding from nonparasitic causes, such as gastric ulcers, duodenal ulcers or gastrointestinal cancer. Iron deficiency causes approximately half of all anemia cases worldwide, and affects women more often than men. 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. == Signs and symptoms == Iron-deficiency anemia is characterized by the sign of pallor (reduced oxyhemoglobin in skin or mucous membranes), and the symptoms of fatigue, lightheadedness, and weakness. None of the symptoms (or any of the others below) are sensitive or specific. Pallor of mucous membranes (primarily the conjunctiva) in children indicates anemia with best correlation to the actual disease, but in a large study was found to be only 28% sensitive and 87% specific (with high predictive value) in distinguishing children with anemia ((Hb) <11.0 g/dl ) and 49% sensitive and 79% specific in distinguishing severe anemia (Hb < 7.0 g/dl).〔() Pallor in diagnosis of iron deficiency in children〕 Thus, this sign is reasonably predictive when present, but not helpful when absent, as only one-third to one-half of children who are anemic (depending on severity) will show pallor. Iron-deficiency must be diagnosed by laboratory testing. Because iron deficiency tends to develop slowly, adaptation occurs and the disease often goes unrecognized for some time, even years; patients often adapt to the systemic effects that anaemia causes. In severe cases, dyspnea (trouble breathing) can occur. Unusual obsessive food cravings, known as pica, may develop. Pagophagia or pica for ice has been suggested to be specific, but is actually neither a specific or sensitive symptom, and is not helpful in diagnosis. When present, it may (or may not) disappear with correction of iron-deficiency anemia. Other symptoms and signs of iron-deficiency anemia include: * Anxiety often resulting in OCD-type compulsions and obsessions * Irritability or a low feeling * Angina * Constipation * Sleepiness/Hypersomnia * Tinnitus * Mouth ulcers * Palpitations * Hair loss * Fainting or feeling faint * Depression * Breathlessness * Twitching muscles * Pale yellow skin * Tingling, numbness, or burning sensations * Missed menstrual cycle * Slow social development * Glossitis (inflammation or infection of the tongue) * Angular cheilitis (inflammatory lesions at the mouth's corners) * Koilonychia (spoon-shaped nails) or nails that are weak or brittle * Poor appetite * Pruritus (itchiness) * Dysphagia due to formation of esophageal webs (Plummer-Vinson syndrome) * Insomnia * Restless legs syndrome 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「Iron-deficiency anemia」の詳細全文を読む スポンサード リンク
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