SPONTANEOUS POSTMENOPAUSAL BONE LOSS IN DIFFERENT SKELETAL AREAS - FOLLOWED UP FOR 15 YEARS

We examined the spontaneous bone loss in two populations of healthy po stmenopausal women, who were followed for 9.5 and 14.5 years without a ny treatment influencing the calcium metabolism The bone mass was meas ured in different skeletal areas: the distal forearm, the lumbar spine , the proximal femur, and the total skeleton. The spontaneous bone los s in the distal forearm, the lumbar spine, and the total skeleton was fitted to an exponential model as a function of years since menopause. The overall bone loss averaged 20-25% of premenopausal bone mass 16 y ears after menopause. The patterns of bone loss were, however, differe nt for the axial and the peripheral skeleton. Thus, the bone loss in t he distal forearm approached a more linear model with a more consisten t bone loss throughout the observation period. In contrast, the lumbar spine showed no significant loss 8 years after menopause. This arrest in bone loss could not be explained by the presence of degenerative c hanges in the lumbar spine and/or aortic calcifications, although thes e changes significantly contributed to 14% increased bone mineral dens ity (p < 0.001). We conclude that bone loss averages 20-25% over the i nitial 16 years of menopause regardless of skeletal site and that patt erns of bone loss are different in the axial and peripheral skeleton.