Anemia of Inflammation

Abstract

The anemia of inflammation (AI), also known as the anemia of chronic disease, is generally believed to be the most common etiology of anemia after the anemia of blood loss/iron deficiency (Cartwright and Lee 1971). It is an underproduction anemia characterized by a relatively low reticulocyte response for the degree of anemia. The traditional definition of the anemia of chronic disease was an anemia in the appropriate clinical setting with low serum iron despite adequate or increased reticular endothelial iron stores (Cartwright and Lee 1971). The term “anemia of inflammation” is less specifically defined. Most would likely use the same definition as the anemia of chronic disease, and some have postulated that the definition should be anemia with an elevated ferritin in the setting of inflammation (Nemeth et al. 2003). The traditional clinical context of the anemia of chronic disease was that it occurred in individuals with chronic (greater than 2 months duration) inflammatory disorders such as rheumatoid arthritis, chronic infectious disorders such as osteomyelitis or tuberculosis, or a malignant disorder (Cartwright and Lee 1971). This definition excluded “chronic” disorders such as renal failure or endocrine deficiencies. The recognition that syndromes associated with anemia of chronic disease include disorders that fell outside the spectrum of the traditional chronic disorders (Cash and Sears 1989) eventually led to the recognition that the unifying feature was the presence of disorders of cytokine activation and that all the pathophysiologic processes involved in the anemia of chronic disease/AI were mediated by inflammatory cytokines (Means 2003). The recognition that not all disorders associated with “anemia of chronic disease” were chronic as defined above and the recognition of the role of the cytokine mediators of inflammation led to the current use of AI to refer to this syndrome.