Pathogenesis and treatment of the anemia of chronic disease.
The anemia of chronic disease may be viewed simply as the anemia that accompanies chronic inflammatory, infectious, or neoplastic disorders. Because these conditions are very common, the anemia of chronic disease is one of the most frequent anemias encountered, and is only second in incidence to iron-deficiency anemia. The anemia of chronic disease is primarily an anemia due to underproduction of red cells, with low reticulocyte production, and is most often a normochromic, normocytic anemia. However, in 30% to 50% of patients, the red cells are hypochromic and microcytic and, most often, the serum iron, total iron-binding capacity, and transferrin saturation are reduced in the presence of adequate iron stores. Although the differential diagnosis includes other underproduction anemias, such as those caused by vitamin and mineral deficiencies, renal failure, endocrinopathies, and myelodysplasia, it generally is easily distinguished from these conditions. Nevertheless, an understanding of the pathogenesis of this condition, as well as a means of alleviating the anemia when the chronic disorder persists, has remained elusive. Recently, major advances have occurred toward understanding the pathogenesis of the anemia of chronic disease and its treatment, and these advances are reviewed.