APPARENT PREMENOPAUSAL AND POSTMENOPAUSAL BONE LOSS EVALUATED BY DXA AT DIFFERENT SKELETAL SITES IN WOMEN - THE OFELY COHORT

We measured the bone mineral density (BMD) at various skeletal sites ( total body, hip, anteroposterior [AP] and lateral [lat] spine, and for earm) in a large population-based cohort of women aged 31-89 years (th e OFELY cohort), and results were analyzed according to age and postme nopausal pars. A significant apparent bone loss was found before the m enopause in cancellous bone, i,e,, at the lat spine and Ward's triangl e (-10%; p < 0.05-0.001). Cross-sectional analysis indicated that, aft er the menopause, apparent bone loss was accelerated within the 10 yea rs following menopause, continued thereafter at all sites except the A P spine, and was again accelerated in elderly menopausal for more than 25 years, Between 30 and 80 years, BMD decreased by 15 to 44% (T scor e -1.6 to -3.4) according to the site, The amount of apparent bone los s was highest at the Ward's triangle when expressed in percentage (44% ) and at the mid- and distal radius when expressed in number of standa rd deviations from the peak bone mass (-3.4). As a result, the percent age of women classified as osteoporotic according to the World Heath O rganization, i,e,, with a T score less than or equal to-2.5, varied su bstantially from site to site and was highest at the radius (37% and 4 6%) and lateral spine (25-31%), intermediate at the Ward's triangle, A P spine, and whole body BRID, and lowest at the whole body bane minera l content, femoral neck, and trochanter (10-12%). In conclusion, this cross-sectional but large study suggests that there is a moderate appa rent premenopausal bone loss that occurs only at cancellous bone sites and that apparent bone loss is accelerated at most skeletal sites aft er the age of 75 years, Because of the highly variable coefficient of variation of the peak bone mass at various skeletal sites, the percent age of postmenopausal women identified as being osteoporotic varies wi dely according to the site of measurement.