Introduction

Anemia represents a common problem among the elderly, with a prevalence of 5–10% for the community-dwelling elderly between 65 and 74 years, and over 20% for seniors 85 years and over. In hospitalized elderly patients and in skilled nursing facilities, anemia prevalence ranges from 40 to 50%. The recent appreciation of the numerous adverse consequences of anemia has generated interest in a more complete understanding of anemia in the elderly. Erythropoietin (EPO) is a hormone central to the regulation of red-blood-cell production that increases in response to falling hemoglobin concentration. Paradoxically, although EPO levels rise slightly with age in non-anemic elderly people, the expected EPO response to anemia appears significantly blunted in the elderly, supporting a relative endogenous EPO deficiency. This relative EPO deficiency, possibly attributable to occult renal insufficiency, may play a central role in the rising prevalence of anemia with advancing age and unexplained anemia in the elderly.

Erythropoiesis

Hematopoiesis, the production of blood elements, occurs in an orderly hierarchical fashion. Maintenance of mature peripheral blood cells (i.e., platelets, red blood cells or erythrocytes, neutrophils, eosinophils, basophils, monocytes, lymphocytes, natural killer cells, and dendritic cells) demands ongoing production to meet losses and respond to stresses. A pluripotent hematopoietic stem cell produces committed progenitors of myeloid, erythroid, and megakaryocytic lineages.