Iron deficiency anemia (IDA) is the commonest cause of anemia in the United States and worldwide. In the United States it has been estimated that some 5%–11% of women and 1%–4% of men are iron deficient, and approximately 5% and 2%, respectively, have IDA.1 Although the cause of IDA may include inadequate iron intake or absorption, which are common in children and premenopausal women, IDA in adult men and postmenopausal women is often the result of chronic occult gastrointestinal bleeding.