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Iron Deficiency Anemia: Overview and Risk Factors

Anemia is a condition in which too few red blood cells are in circulation. Iron deficiency is the most frequent cause of anemia, and it results from inadequate levels of iron in the body, causing decreased production of red blood cells. Symptoms are nonspecific and include weakness and fatigue, irritability and mood swings, headache, exercise intolerance, decreased appetite (especially in children), pica (which may include chewing ice), pallor (in dark-pigmented persons, pallor may be evident in sclera and palmar surfaces), shortness of breath, and restless leg syndrome.

The most common cause of iron deficiency is blood loss, usually through menorrhagia or gastrointestinal bleeding. The condition may also be caused by inadequate iron intake, increased iron utilization due to rapid growth (as in infancy, adolescence, and pregnancy), malabsorption (eg, celiac disease or previous gastric surgery, including gastric bypass), phlebotomy, hemolysis, or other rare instances such as intense athletic training. Anemia develops after iron stores (found mainly in the liver, spleen, bone marrow, and the blood itself) are depleted.

According to the Centers for Disease Control and Prevention (CDC),1 an estimated 7% of toddlers, 4% to 5% of children, 9% to 16% of menstruating females, and 2% of pubescent and adult males have iron deficiency, with smaller percentages having anemia. Mild iron deficiency with depleted iron body stores may produce symptoms without resulting in an anemia.

Risk Factors

Age. Children have a greater risk of iron deficiency anemia due to rapid growth, particularly in the first 2 years of life.

Gender. Women generally consume less iron than men (due to a lower energy requirement) and may have a greater need for iron, depending on their stage of life. On average, a menstruating woman loses 30 to 45 mg of iron per month. Pregnancy and delivery together use about 1 gram of maternal iron. On average, breast-feeding a child uses a total of about 1 gram of maternal iron in the first year of life.

Peptic ulcer disease and gastritis. These disorders lead to blood loss, which can deplete iron stores. Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) are often contributing factors.

Malignancy. Esophageal, gastric, and other gastrointestinal cancers often cause occult bleeding.

Excessive exercise. Blood losses may occur due to intense exercise: for example, as occurs in "foot strike" hemolysis in distance runners. Iron losses also result from increased sweating. Such losses may predispose adolescent female athletes in particular to frank anemia.2

Dietary and absorptive factors (see Nutritional Considerations).

Iron Deficiency Anemia: Diagnosis >>