Estimation of bone mineral density and bone loss by means of bone metabolic markers in postmenopausal women

We have examined healthy women (51 premenopausal women and 30 postmenopausal women; age 28-59) for lumbar bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA) and assessed metabolic bone markers, such as type I procollagen carboxy-terminal propeptide (P1CP), pyridinoline (PYR), deoxypyridinoline (DPYR), osteocalcin (BGP) and alkaline phosphatase (ALP). BMD was assessed once a year in three consecutive years. Correlations among the BMD, BMD changes and levels of bone markers in samples at the first DXA assessment were studied. In pre-menopausal women, none of the biochemical markers were correlated with the BMD or changes in BMD. In contrast, BMD in post-menopausal women correlated (negatively) well with levels of P1CP, DPYR, PYR and ALP declining in this order, and a significant positive correlation was observed between the rate of bone loss in postmenopausal women and the P1CP concentration. PYR and DPYR also had a tendency to correlate. Combinations of several bone markers improved the correlation. These results show that by measuring several bone specific biochemical markers in postmenopausal women, one can estimate their rates of bone loss as well as their present BMDs. The measurement of biochemical bone markers will therefore be very useful in evaluating bone status and would be applicable in screening postmenopausal osteopenia.