Definition of Iron deficiency anemia:

Anemia is a condition where red blood cells are not providing adequate oxygen to body tissues. There are many types and causes of anemia. Iron deficiency anemia is a decrease in the number of red cells in the blood caused by too little iron.

See also: Iron-deficiency anemia - children.

Causes, incidence, and risk factors:

Iron deficiency anemia is the most common form of anemia. About 20% of women, 50% of pregnant women, and 3% of men are iron deficient. Iron is an essential component of hemoglobin, the oxygen-carrying pigment in the blood. Iron is normally obtained through the food in your diet and by recycling iron from old red blood cells. Without it, the blood cannot carry oxygen effectively -- and oxygen is needed for the normal functioning of every cell in the body.

The causes of iron deficiency are too little iron in the diet, poor absorption of iron by the body, and loss of blood (including from heavy menstrual bleeding). It can also be related to lead poisoning in children.

Anemia develops slowly after the normal stores of iron have been depleted in the body and in the bone marrow. Women, in general, have smaller stores of iron than men and have increased loss through menstruation, placing them at higher risk for anemia than men.

In men and postmenopausal women, anemia is usually caused by gastrointestinal blood loss associated with ulcers, the use of aspirin or nonsteroidal anti-inflammatory medications (NSAIDS), or certain types of cancer (esophagus, stomach, colon).

Celiac disease may cause iron deficiency anemia.

High-risk groups include:

• Women of child-bearing age who have blood loss through menstruation
• Pregnant or lactating women who have an increased requirement for iron
• Infants, children, and adolescents in rapid growth phases
• People with a poor dietary intake of iron

Risk factors related to blood loss are peptic ulcer disease, long term aspirin use, and colon cancer.