[The development of bone mass during a lifetime].

The authors present a reminder of the methods used to evaluate the bone mass and density and, with population studies, specify the profile and significance of the physiological osteopenia in both sexes. Analysis of these studies shows that the age of onset of the bone loss and its percentage vary markedly between the various sites of the skeleton, according to the type of bone, cortical or trabecular. It seems that the "smooth" aspect of the physiological osteopenia curves obtained is women during population studies, essentially results from the disparity between the times of menopause. A general protocol of the physiological osteopenia, synthesizing all data collected with nine different methods of measurement of the mineral bone content, is presented for educational purposes.