Blood cell parameters do not change during physiological human ageing

Despite the considerable amount of data published during the last 30 years concerning the hematological status of the aged, practitioners are still confronted with the problem of 'normal' or 'physiological' values in these subjects. Indeed, significantly different values are presented in the literature as normal for the aged, apparently depending on the various types of populations studied. Criteria used to define the subjects as 'normal' could be the main factor responsible for this discrepancy. Based on this hypothesis, we determined the values of usual blood cell parameters in two groups of apparently healthy subjects of over 75 years of age. Subjects of group A (16 men and 13 women) were selected according to the stringent criteria of the Senieur protocol and subjects of group B (15 men and 20 women) were recruited using 'conventional' admission criteria. For both groups, sex-matched young controls aged 20-29 years were tested in parallel. No clinically significant alteration was observed in group A, whereas more pronounced differences were found in group B. Our results confirm the necessity for stringent selection criteria in biological investigations in gerontology. Moreover, they demonstrate that blood cell parameters are not altered in the aged, provided that the latter are really 'healthy'.