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.

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.

• Pale skin color
• Fatigue
• Irritability
• Weakness
• Shortness of breath
• Sore tongue
• Brittle nails
• Unusual food cravings (called pica)
• Decreased appetite (especially in children)
• Headache - frontal
• Blue tinge to sclerae (whites of eyes)

• Low hematocrit and hemoglobin (red blood cell measures)
• Small red blood cells
• Low serum ferritin
• Low serum iron level
• High iron binding capacity (TIBC) in the blood
• Blood in stool (visible or microscopic)

The cause of the deficiency must be identified, particularly in older patients who are most susceptible to intestinal cancer.

Oral iron supplements are available (ferrous sulfate). The best absorption of iron is on an empty stomach, but many people are unable to tolerate this and may need to take it with food. Milk and antacids may interfere with absorption of iron and should not be taken at the same time as iron supplements. Vitamin C can increase absorption and is essential in the production of hemoglobin.

Supplemental iron is needed during pregnancy and lactation because normal dietary intake rarely supplies the required amount.

The hematocrit should return to normal after 2 months of iron therapy. However, iron should be continued for another 6 - 12 months to replenish the body's iron stores, which are stored mostly in the bone marrow.

Intravenous or intra-muscular iron is available for patients who can't tolerate forms taken by mouth.

Iron-rich foods include raisins, meats (liver is the highest source), fish, poultry, eggs (yolk), legumes (peas and beans), and whole grain bread.

With treatment, the outcome is likely to be good. Usually, blood counts will return to normal in 2 months.

There are usually no complications. However, iron deficiency anemia may recur, so regular follow-up is encouraged. Children with this disorder may be more susceptible to infection.

Call for an appointment with the health care provider if symptoms suggestive of this disorder develop or if blood is noted in the stool.

Everyone's diet should include enough iron. Red meat, liver, and egg yolks are important sources of iron. Flour, bread, and some cereals are fortified with iron. If you aren't getting enough iron in your diet (uncommon in the U.S.), take iron supplements.

During periods of increased requirements, such as pregnancy and lactation, increase dietary intake or take iron supplements.

Brotanek JM, Gosz J, Weitzman M, Flores G. Iron deficiency in early childhood in the United States: risk factors and racial/ethnic disparities. Pediatrics. Sep 2007;120(3):568-75.

Ginder GD. Microcytic and hypochromic anemias. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 163.

Killip S, Bennett JM, Chambers MD. Iron deficiency anemia. Am Fam Physician. Mar 1 2007;75(5):671-8.