BIOCHEMICAL MARKERS OF BONE TURNOVER TO MONITOR THE BONE RESPONSE TO POSTMENOPAUSAL HORMONE REPLACEMENT THERAPY

Hormone replacement therapy (HRT) prevents postmenopausal bone loss, and is therefore increasingly prescribed to prevent the development of postmenopausal osteoporosis. Because of individual differences in the response to HRT as well as problems with compliance, it has been debated how the skeletal response to HRT should be monitored. When estrogen production decreases at the menopause, a number of biochemical markers of bone turnover increase considerably in the order of 50%-100% from baseline. When HRT is instituted, the markers decrease again within the following 3-6 months. In the present prospective study we investigated whether the determination of biochemical markers of bone turnover may be useful for monitoring the skeletal effect of HRT. Seventy-six early postmenopausal women received HRT and 43 received placebo. The treatment period was 24 months and the women were followed with repeated bone mass measurements (every 3 months) which allowed calculation of the bone loss. Serum and urine samples were collected at 3, 6, 12 and 24 months. The placebo group lost a significant amount of bone mineral density in both the forearm and the spine (p <0.001), whereas the HRT group did not. There was, however, a relatively large overlap of values between the HRT and placebo groups, especially in the spine. After 3 months' treatment the correlation between the changes in the markers and the bone loss was r = 0.59, and this value increased to r = 0.66 at 6 months and r = 0.76 and r = 0.77 at 12 and 24 months, respectively. The present study thus indicates that biochemical markers of bone turnover may be of value for monitoring the bone response to HRT.