Differential time-related effects of conjugated equine estrogen on bone metabolism in oophorectomized women.

OBJECTIVE

The effects of conjugated equine estrogen (CEE) on bone mineral density (BMD) and biochemical indices of bone remodeling in oophorectomized women were studied for 3 years during estrogen replacement therapy (ERT) to investigate whether 0.625 mg/day of CEE alone prevent acute bone loss in the early stage of surgical menopause.

METHODS

We divided the subjects into three groups according to interval between oophorectomy and the start of ERT (group 1: less than 2 years after surgery, n = 31; group 2: 2-5 years after surgery, n = 29; and group 3: more than 5 years after surgery, n = 27). Vertebral BMD was measured using dual energy X-ray absorptiometry (DEXA). Two biochemical indices of bone metabolism, urinary deoxypyridinoline (DPyr) and serum intact human osteocalcin (hOC) were also measured.

RESULTS

In group 1, continuous ERT with 0.625 mg/day of CEE could not prevent a BMD decrease within the first year. However, by the end of the second year, BMD was restored to the pre-ERT. The same dosage of CEE significantly increased BMD in groups 2 and 3 by the end of the first year. DPyr and hOC levels both decreased dramatically in the initial 6 months of therapy and were stable thereafter.

CONCLUSION

In the initial 2-year period after oophorectomy, 0.625 mg/day of CEE alone could not prevent acute bone loss suggesting that additional therapy for the prevention of osteoporosis may be needed.