Anemia and iron deficiency in Crohn's disease.

: Anemia is a common extraintestinal complication of Crohn's disease (CD) mainly caused by iron deficiency, that affects the quality of life in CD patients. Elucidation of the etiology and pathology of iron-deficiency anemia (IDA) and anemia of chronic diseases (ACD) has developed in recent years. Common biochemical parameters of iron status are insufficient for assessment of patients with anemia and CD. Thus, novel iron indices are required for accurate assessment in IDA patients with CD. Oral iron supplementation for IDA treatment is common and is associated with minor gastrointestinal side effects. Intravenous substitution improves safety profiles but may be not tolerable in some patients. Fortunately, additional therapies for anemia of active CD have emerged in recent years.: Here, we propose the review article on the link among anemia, iron deficiency, and Crohn's disease. We discuss the current diagnosis and therapy of anemia and iron deficiency in CD and propose the new directions for future research.: Exploring pathogeneses and treatments of anemia and iron deficiency in Crohn's disease will develop potential tools for early diagnosis and effective treatment of anemia in CD patients, and improve their life quality.