Anemia - Introduction

Iron Deficiency Anemia

Iron deficiency anemia occurs when the body lacks mineral iron to produce the hemoglobin it needs to make red blood cells. In general, there are three stages leading from iron deficiency to anemia:

First, there is an insufficient supply of iron and iron stores are depleted in the bone marrow. This stage generally has no symptoms.
Second, iron deficiencies develop and begin to affect hemoglobin production. (Tests, in such cases, reflect low hemoglobin and hematocrit levels.)
Hemoglobin production declines to the point where anemia develops.

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Most of the iron used in the body can be recycled from blood and reused. Nevertheless, iron deficiency can occur from a number of conditions.

Iron-Poor Diets. Lack of iron in the diet is not a common cause of iron deficiency anemia, except in infants. In fact, most Americans adults may be consuming too much iron in their diet. Most of the iron in red blood cells is recycled and reused. In general, most people need just 1 mg and menstruating women need 2 mg of extra iron each day, which a healthy diet easily provides. Iron-poor diets are only a cause of anemia in people with existing risks for iron deficiency.

Peptic Ulcers and Their Causes. The bacteria H. pylori are known to be primary causes of peptic ulcers, which, in turn, is an important cause of anemia in older people. Anemia in such cases may be less likely to result from bleeding ulcers but more to impaired iron or vitamin B12 absorption caused by the presence of the bacteria. The bacteria, in fact, may also bind to iron and reduce its availability in the intestine, causing iron deficiency anemia.

Medications (NSAIDs). Aspirin and drugs such as ibuprofen and naproxen are called nonsteroidal anti-inflammatory drugs (NSAIDs). About 70% of long-term users of these medications have some sign of gastrointestinal bleeding, although it is rarely significant enough to cause anemia. Two laboratory studies suggest that aspirin -- but not other NSAIDs -- may stimulate the production of ferritin, a blood protein that binds iron. Since low ferritin levels indicate iron deficiencies, this effect could mask the true cause of anemia. However, a clinical study found that aspirin users actually have low ferritin levels, possibly because of gastrointestinal bleeding. More research is needed.

Bleeding Due to Other Medical Conditions. Iron deficiencies most commonly occur from internal blood loss due to other conditions that range in severity from hemorrhoids, heavy menstruation, or benign colon polyps to colon cancer. Very heavy periods (menorrhagia) are the most common causes of anemia in premenopausal women. Cancers of the gastrointestinal tract account for 2% of cases of iron deficiency (the rate is higher when menorrhagia is excluded).