Asynchrony between the rates of standing height gain and bone mass accumulation during puberty.

During puberty, the marked increased in both standing height and bone mass appear to be dissociated in time, the former occurring earlier than the latter. However, the age or pubertal stage at which this dissociation is maximal in girls as opposed to boys, and whether this dissociation is similar at all parts of the skeleton, are not clearly established. Standing height and bone mineral mass, as assessed by measuring areal bone mineral density (BMD), at the levels of the lumbar spine, femoral neck and midfemoral shaft, were measured in 98 females and 100 males between the ages of 9 and 19 years twice at a 1-year interval. In males, the greatest difference between height and BMD gains occurred in the 13-14 year age group and was more pronounced for the lumbar spine and femoral neck than for the midfemoral shaft. In females, the greatest difference was detectable at a younger age (11-12 year age group) and appeared to be of a lower magnitude than in males. In both genders, the maximal difference occurred during the period of peak height velocity, which corresponded to the pubertal stages P2-P3. Such a dissociation between the rates of statural growth and mineral mass accrual could define a state of relatively low bone mass and contribute to the higher incidence of fracture known to occur at the age and/or pubertal stage when this dissociation is maximal.