Anemia

Anemia (American English) or anaemia (British English) is a lack of red blood cells and/or hemoglobin. This results in a reduced ability of blood to transfer oxygen to the tissues. Hemoglobin (theoxygen-carrying protein in the red blood cells) has to be present to ensure adequate oxygenation of all body tissues.
Anemia is the most common disorder of the blood. There are several kinds of anemia,produced by a variety of underlying causes. Anemia is classified by the size of the red blood cell: decreased (microcytic), normal (normocytic) or enlarged (macrocytic ormegaloblastic).

Anemiagoes undetected in many people, and symptoms can be vague. Most commonly, a feeling of weakness or fatigue is reported.Shortness of breath is reported in more severe cases. Very severe anemia prompts acompensatory response where cardiac output is markedly increased, leading to palpitations and sweatiness; this process can lead to heart failure in elderly people.
Pallor (pale skin and mucosallinings) is only notable in cases of severe anemia, and is therefore not a reliable sign.

Microcytic anemia
The most common type of anemia overall is iron deficiency anemia, which is most oftenmicrocytic. Much rarer causes (apart from communities where these conditions are prevalent) are hemoglobinopathies such as sickle cell anaemia and thalassemia.
Iron deficiency anemia is caused when thedietary intake or absorption of iron is insufficient. Iron is an essential part of hemoglobin, and low iron levels result in decreased incorporation of hemoglobin into red cells. In the United States, 20%of all women of childbearing age have iron deficiency anemia, compared with only 2% of adult men. The principal cause of iron deficiency anemia in premenopausal women is blood lost during menses.Studies have shown that iron deficiency without anemia causes poor school performance and lowerIQ in teenage girls. In older patients, iron deficiency anemia of often due to bleeding lesions of...