Risk Factors:

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.

Infants and Children

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:

• Stopping breastfeeding too early or using formula that isn't iron-fortified.
• Bottle-feeding too long. Studies indicate that the longer children are bottle-fed, the greater the risk for iron-deficiency and anemia. Toddlers 12 months and older should not drink more than 2 cups of milk a day. Cowâ ' s milk is good for children, but it does not contain enough iron. Too much milk can decrease childrenâ ' s appetite and prevent them from eating the iron-rich food they need. When babies who are bottle-fed are 7 - 9 months old, they should be weaned from bottles and given sippy cups. By the age of 12 months, all children should be using a cup instead of a bottle.
• Toddlersâ ' preferences for iron-poor food. Parents should make sure that their children eat iron-rich foods, such as beans, meat, fortified cereals, eggs, and green leafy vegetables

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.

Premenopausal Women

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:

• Heavy menstruation for longer than 5 days
• Abnormal uterine bleeding, such as from fibroids
• Pregnancy. About 20% of women in industrialized countries have iron deficiency during pregnancy. Multiple pregnancies and births significantly increase the risk.

Older Adults

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.

Alcoholism

People with alcoholism are at risk for anemia both from internal bleeding as well as folate- and vitamin B deficiency-related anemias.

Iron-Poor Diets

Although most Americans probably consume too much iron in their diets, some people may be at risk for diet-related iron deficiencies, including:

• People whose diets are high in processed foods and lack any meat.
• Strict vegetarians. Vegetarians who avoid all animal products may have a slightly higher risk for deficiencies in iron and some B vitamins. Although dried beans and green vegetables often contain iron, it is less easily absorbed from plants than from meat. Fortunately, most commercial cereals are fortified with vitamin B12 and folic acid (the synthetic form of folate).

Chronic or Critical Illnesses

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.

Excessive Exercise

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.

Pregnancy

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:

• It increases the body's demand for folic acid and, therefore, poses a risk for deficiencies and an increased risk for megaloblastic anemia. Low levels of folate during pregnancy increase the risk of neural tube defects in newborns.
• It increases the body's demand for iron, thus posing a risk for iron deficiency anemia. Pregnant or nursing women need 30 mg of iron per day. Maternal iron deficiency anemia is associated with increased weight or size of the placenta, a condition that may later pose a risk for high blood pressure in the offspring. Pregnant women with low hemoglobin levels (the iron-bearing component in the blood) have an elevated risk for pre-term or low birth weight infants.
• Pregnancy is also associated with fluid retention, which in turn may produce high volumes of plasma (the fluid component of blood). This can dilute red blood cells, which may lead to anemia.
• During delivery, heavy bleeding or multiple births can cause postpartum anemia, which occurs in about 10% of women. Postpartum anemia can last 6 - 12 months after giving birth.