LONGITUDINAL MEASUREMENT OF REGIONAL AND WHOLE-BODY BONE MASS IN YOUNG HEALTHY-ADULTS

The so-called peak bone mass (PBM) represents the highest amount of bo ny tissue achieved during life at a given site of the skeleton. It has been suggested that PBM might be achieved as late as the fourth decad e, but recent data have indicated that PBM is already achieved by the end of sexual maturation, namely at the end of the second decade. The solving of this apparent controversy is of interest for a better under standing of bone homeostasis and for defining the cohort of normal sub jects to be evaluated in order to establish a PBM reference range - ne cessary for the diagnosis of osteoporosis and evaluation of the fractu re risk. To study bone mass evolution in young healthy adults and to d etermine whether such a cohort can be used to establish PBM reference values, we measured bone mineral density (BMD) in sixty 20- to 35-year -old young healthy adults by dual-energy X-ray absorptiometry at the l evels of the lumbar spine (in both anteroposterior and lateral views), femoral neck, trochanter region, total hip and of Ward's triangle, as well as whole-body BMD and bone mineral content (BMC) in cross-sectio nal and longitudinal studies. In the cross-sectional analysis, none of the bone mass variables was dependent on age using linear regression analysis. The longitudinal study indicated that the mean changes in lu mbar spine, proximal femur and whole body BMD or BMC determined after a 1-year interval were not statistically different from zero in either females or males aged 20-35 years. In conclusion, the present results confirm that at the levels of lumbar spine and proximal femur, two si tes particularly at risk of osteoporotic fractures, PBM can be achieve d before the third and fourth decades in both male and female normal s ubjects.