The Global Burden of Anemia

Anemia is defined by a decrease in the number of circulating erythrocytes (i.e. red blood cells). Hemoglobin concentrations are typically used as a surrogate marker for red blood cell mass, with anemia typically being defined by a hemoglobin concentration less than 13 g/dL in adult men and less than 12 g/dL in adult, non-pregnant women. Anemia is remarkably common globally, though low- and middle-income countries bear the greatest burden. Anemia may be defined by the underlying pathological processes that lead to its development, the speed of development, and by laboratory and morphological features. With the exclusion of acute blood loss anemia, iron deficiency is the leading cause of global anemia, which is particularly common in children and women. As erythrocytes are the primary vehicle for oxygen delivery to tissues, it is perhaps not surprising that anemia is associated with impaired aerobic capacity, organ dysfunction, and mortality. Additionally, anemia is the leading risk factor for allogeneic red blood cell transfusion, which further contributes to patient morbidity. Despite being remarkably common, preventable, and readily treatable, anemia is often neglected by clinicians, particularly in hospitalized settings.