[Relative contribution of ageing and menopause to the changes of lumbar bone density in 1,400 Beijing women].

OBJECTIVE

To study the pattern of bone mass changes in women's lumbar spine and obtain evidence to guide the prevention of postmenopausal osteoporosis.

METHOD: Bone mineral content (BMC) and bone mineral density (BMD) of lumbar 1-4 in 1 400 Beijing women aged 20-85, were measured by dual energy X-ray absorptiometry.

RESULTS

(1) Both BMC and BMD increased after age 20, reached the peak at the age of 30, and decreased significantly after the age of 50; (2) There was no significant change of BMC and BMD after the age of 25 in premenopausal women. Bone loss accelerated in the first 10 years after menopause. Women who experienced menopause early had lower bone mass. (3) The prevalence of osteoporosis in 1 121 postmenopausal women was 17.40%.

CONCLUSION

Significant bone mass loss of lumbar spine occurs during the first decade following menopause, which is the key period for preventing osteoporosis.