The role of bone loss

Abstract

Our longitudinal studies of early postmenopausalwomen have shown that there are two characteristic groups. Approximately 35% lose significant amounts of bone mineral (the “fast losers”), whereas approximately 65% lose only a minor amount of bone mineral (the “normal losers”). The rate of bone loss in postmenopausal women may be indirectly assessed by use of a number of biochemical markers. New markers have recently been developed, i.e., more specific and robust markers of both bone resorption and formation. The urinary concentration of degradation products of type I collagen and osteocalcin assays that are stable in serum may optimize the procedure to assess the rate of loss. We and others have shown that these markers correlate to the rate of bone loss with fairly high r values. A prospective 12-year study revealed that the fast bone losers still had significantly higher bone turnover than the normal bone losers. The role of baseline bone mass and rate of loss on fracture risk was evaluated. The data showed that a low baseline bone mass (below -1 SD) and a fast rate of loss predisposed to fracture to the same extent with an odds ratio of approximately 2. A combination of a low baseline bone mass and a fast rate of loss increased the odds ratio of having a fracture. In conclusion, these data suggest that a low bone mass and a fast rate of bone loss play equal roles for the future risk of fracture.