Hematopoietic function in the elderly.

Very little information is available on the effect of aging on human bone marrow function. In reviewing both murine and human studies on bone marrow function in the elderly, it may be concluded at present that there is an increasing incidence of anemia that develops with aging in humans. Extensive animal and limited human data support decreased marrow reserve capacity with decreased hormonal responsiveness to hematologic stress as the most likely cause. In normal human life spans, marrow stem cells do not appear to wear out, and, finally, clinicians are cautioned not to attribute anemia per se simply to aging. Any elderly individual with unexplained anemia must be fully evaluated for the possibility of occult gastrointestinal blood loss, marrow failure syndrome, or hemolytic state before his/her anemia is attributed to age alone. Much additional research remains to be done on hematopoietic function in aged individuals.