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Iron deficiency (sideropenia or hypoferremia) is the most common nutritional deficiency in the world.〔 electronic-book ISBN 978-94-007-5561-1 electronic-〕 Iron is present in all cells in the human body and has several vital functions, such as: carrying oxygen to the tissues from the lungs as a key component of the hemoglobin protein; acting as a transport medium for electrons within the cells in the form of cytochromes; facilitating oxygen use and storage in the muscles as a component of myoglobin and as an integral part of enzyme reactions in various tissues. Too little iron can interfere with these vital functions and lead to morbidity and death. Total body iron averages approximately 3.8 g in men and 2.3 g in women. In blood plasma, iron is carried tightly bound to the protein transferrin. There are several mechanisms that control human iron metabolism and safeguard against iron deficiency. The main regulatory mechanism is situated in the gastrointestinal tract. When loss of iron is not sufficiently compensated by adequate intake of iron from the diet, a state of iron deficiency develops over time. When this state is uncorrected, it leads to iron deficiency anemia. Before anemia occurs, the medical condition of Iron Deficiency without anemia is called Latent Iron Deficiency (LID) or Iron-deficient erythropoiesis (IDE). Untreated iron deficiency can lead to iron deficiency anemia— a common type of anemia. Anemia is a condition characterized by inadequate red blood cells (erythrocytes) or hemoglobin. Iron deficiency anemia occurs when the body lacks sufficient amounts of iron, resulting in reduced production of the protein hemoglobin. Hemoglobin binds to oxygen, thus enabling red blood cells to supply oxygenated blood throughout the body. Children, pre-menopausal women (women of child-bearing age) and people with poor diet are most susceptible to the disease. Most cases of iron deficiency anemia are mild, but if not treated can cause problems like fast or irregular heartbeat, complications during pregnancy, and delayed growth in infants and children.〔(【引用サイトリンク】title=Iron and Iron Deficiency )〕 ==Signs and symptoms== Symptoms of iron deficiency can occur even before the condition has progressed to iron deficiency anemia. Symptoms of iron deficiency are not unique to iron deficiency (i.e. not pathognomonic). Iron is needed for many enzymes to function normally, so a wide range of symptoms may eventually emerge, either as the secondary result of the anemia, or as other primary results of iron deficiency. Symptoms of iron deficiency include: * fatigue * dizziness * pallor * hair loss * twitches * irritability * weakness * pica * brittle or grooved nails * Plummer-Vinson syndrome: painful atrophy of the mucous membrane covering the tongue, the pharynx and the esophagus * impaired immune function *pagophagia *restless legs syndrome Continued iron deficiency may progress to anaemia and worsening fatigue. Thrombocytosis, or an elevated platelet count, can also result. A lack of sufficient iron levels in the blood is a reason that some people cannot donate blood. 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」の詳細全文を読む スポンサード リンク
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