THE EFFECTS OF MENOPAUSE ON LONGITUDINAL BONE LOSS FROM THE SPINE

Two hundred and thirty women aged 45-66 years were divided into three groups according to their menopausal status and were followed to asses s the changes in vertebral bone mineral density (BMD). These included 71 premenopausal, 42 perimenopausal, and 117 postmenopausal women. Men opausal status was assessed through menstrual history and plasma conce ntrations of 17beta estradiol and luteinizing hormone. BMD was measure d by dual photon absorptiometry between 2 and 5 times over an average period of 27 months, and annual rates of changes were calculated by li near regression. BMD decreased significantly (P < 0.0001) in the three groups during the follow-up. Mean (+/- SD) annual rate of change was -0.79 +/- 1.5% for premenopausal, -2.35 +/- 1.5% for perimenopausal, a nd -1.24 +/- 1.5% for postmenopausal women. There was no difference in the rates of bone loss between the perimenopausal group and the postm enopausal group within 3 years after menopause (1-2 years: -2.34 +/- 2 .1%; 2-3 years: -1.9 +/- 1.5%). Thereafter, rates decreased exponentia lly with time since menopause to fall out at the same level as the pre menopausal level. These longitudinal data indicate that vertebral bone loss begins before menopause and accelerates sharply during menopause to decline exponentially with time after 3 years.