Circulating Blood Elements

the concentration of pluripotent hemopoietic progenitors in the circulation of the aged, despite that the baseline concentrations of these elements were the same in both groups, 27 and the risk of neutropenia, neutropenic infections and thrombocytopenia following cytotoxic chemotherapy increased after age 60 28-39. The fact that the prevalence and incidence of anemia of unknown causes increase with age may also be construed as evidence of progressive hemopoietic insufficiency 40-43.

These observations support an age-related decline in hemopoietic reserve that may be of consequence in the presence of severe and prolonged hemopoietic stress. In condition of homeostasis, the hemopoietic activity appears adequate to preserve a normal peripheral blood count throughout a person's lifetime, in the majority of individuals 44-45. Even among the oldest old, it should not be assumed that anemia, neutropenia, thrombocytopenia or pancytopenias are a natural consequence of age.

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