Changes of Peripheral Blood Figures and Erythropoiesis in the Aged

Abstract

Physiological changes of the peripheral blood figures and erythropoiesis were studied in the elderly subjects with particular reference to effects of aging. They consisted of 1224 healthy subjects over 60 years of age.
The results obtained were as follows:
1) Hemoglobin concentration, erythrocytes counts and hematocrit values in the aged gradually decreased with their advance in years. These parameters were observed to be higher in the males than in the females, although this difference was less evident in the older subjects of the group. Of the erythrocytic indices, MCV slightly increased with aging whereas MCH showed no change. Furthermore, leucocytes counts declined to decrease with aging. Thrombocytes counts showed no change.
Absolute counts of the reticulocytes in peripheral blood decreased in those over 70 years of age, indicating the reduction of effective erythropoiesis in the aged. No abnormality of the fragility of erythrocytes was observed.
2) Erythroid stem cells, represented by erythropoietin responsive cells (ERC), decreased significantly in the subjects over 70 years of age, compared with those under 50 years of age. Although ERC showed no relationship to the proportion of erythroblasts in the bone marrow, a significant correlation between ERC size and absolute counts of reticulocytes was observed.
From the results described above it is evident that a decrease in erythropoiesis is a contributory factor in “senile anemia”. Although the decrease in erythropoiesis was postulated to ensure from the reduction of hemopoietic stem cells, the mechanism by which the size of hemopoietic stem cells compartment decreases in the aged is not still clear.