[Determination by flow cytometry of reference values of erythrocyte parameters in aged subjects]

Normal values for hemoglobin and hematocrit have been established for healthy young adults, but it is unknown whether age-related decline in hematological values occurs in the elderly. We compared normal values of hematological parameters in healthy adults and healthy persons aged 65 years and over using flow cytometry.

Erythrocyte and reticulocyte parameters were determined in 585 subjects (294 men and 206 women aged 26 to 64 years, and 37 men and 48 women aged 65 years and over), living independently and without medication, symptom and disease, using Technicon H1 (Bayer) and R2000 (Roche) analyzers. Serum erythropoietin levels, red cell folate and creatinine clearance were determined in subjects aged 65 years and over.

Irrespective of subject age, hemoglobin (Hb), hematocrit (Hct), red blood cell count (RBC), mean cell volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) were higher in males than in females, but sex-related differences tended to decrease with aging. In males, there was a trend toward lower Hb and Hct with aging, due to an increase in RBC, MCV and MCH. In females, Hb and Hct (p < 0.05) increased with aging, due to a trend toward higher values of RBC, MCV and MCH. Red blood cell distribution width and hemoglobin distribution width were not modified by aging. Despite these age-related changes in erythrocyte parameters, values for anemia defined in adults appear appropriate for geriatric subjects (Hb < 130 g/l in males and Hb < 120 g/l in females). Reticulocyte count and creatinine clearance decreased in men and women aged 65 years and over (p < 0.05), whereas erythropoietin levels and red cell folate were not influenced by aging.

Normal erythrocyte values defined in adults are appropriate for evaluating hematological test results in older individuals. The decrease in reticulocyte count observed in men and women aged 65 years and over does not appear to be linked to a decrease in erythropoietin production with aging.