Iron deficiency; Pernicious anemia
Although nutritional iron-deficiency anemia has declined in industrialized nations, it affects an estimated 2 billion people worldwide. Even in the U.S., iron deficiency is the most prevalent nutritional deficiency. It is highly associated with poverty. People in lower socioeconomic groups have double the risk of those who are middle or upper class.
Among Americans with iron deficiency anemia, young children have the highest risk followed by premenopausal women. Adolescent and adult men and postmenopausal women have the lowest risk. Men, in fact, are at risk for iron overload, probably because of their higher meat intake and their reduced iron loss.
General Risk Factors for Anemia in Infants and Children. Up to 20% of American children and 80% of children in developing countries become anemic at some point during their childhood and adolescence. Iron deficiency is the most common cause in children, but other forms of anemia, including hereditary blood disorders, can also cause anemia in this population. Hispanic American children have double the rates of iron deficiency as African-American and Caucasian children.
Iron deficiency affects about 9% of children younger than 2 years. About 3% of children in this age group are anemic as a result. Children in lower-income homes are at higher risk than those in higher income homes. However, children in any income group can develop iron deficiency.
Young children 9 - 18 months have the highest risk for iron deficiency anemia in the U.S. Such children also are at great risk for problems in mental development from anemia. Infant boys may have 10 times more risk than baby girls. In general, full-term, breast-fed infants have enough iron stores for their first 6 months of life. After that, they must rely on other sources for iron.
Iron-deficiency anemia in infants and small children can be due to one or more of the following factors:
Better social services and more accurate ways of diagnosing and monitoring anemia are needed in these high-risk groups. There is still considerable debate on how to define iron deficiency and anemia in infants. New research suggests that a reticulocyte hemoglobin content (CHr) test may be better than a standard hemoglobin test for detecting iron deficiency in babies. Reticulocytes are immature red blood cells. The CHr test measures the amount of hemoglobin in these cells.
Up to 10% or more of adolescent and adult women under 49 years are iron deficient. Hispanic American and African-American women have double the prevalence for anemia compared to Caucasian women. The risk for anemia in adolescent girls is about 3%. Anemia is generally mild in young women, however, and is more likely to occur with one or more of the following conditions:
About 10% of adults age 65 years and older have anemia. For patients in nursing homes, about 50% are anemic. Causes of anemia in older adults include nutritional deficiencies, chronic inflammatory disease, and chronic renal disease.
People with alcoholism are at risk for anemia both from internal bleeding as well as folate- and vitamin B deficiency-related anemias.
Although most Americans probably consume too much iron in their diets, some people may be at risk for diet-related iron deficiencies, including:
Anyone with a chronic disease that causes inflammation or bleeding is at risk for anemia. Critical illness in the intensive care unit is also highly associated with anemia.
Working out regularly may cause some iron loss, which is comparable to that from menstruation and rarely worrisome. Dietary choices may account for most cases of sports anemia. Intense, sustained exercise, such as that performed by marathon runners, may cause a condition called sports anemia, which may be due to slight gastrointestinal bleeding, damaged red blood cells, low iron intake, or poor intestinal absorption of iron.
Iron deficiency occurs in 20% of pregnant women in developed countries. Even worse, 50% or more of women in nonindustrialized nations become iron deficient, and 30 - 50% are deficient in folic acid. Severe anemia is associated with a higher mortality rate among pregnant women. Mild-to-moderate anemia, however, does not pose any elevated risk.
Pregnancy increases the risk for anemia in different ways:
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