OOPHORECTOMY AND SPINE BONE-DENSITY - EVIDENCE OF A HIGHER RATE OF BONE LOSS IN SURGICAL COMPARED WITH SPONTANEOUS MENOPAUSE

To compare the influence of spontaneous and surgical menopause on bone loss, we measured with dual x-ray absorptiometry (DXA) the spinal bon e mineral density (BMD) in 513 women recruited at the Menopause Clinic at Ferrara University Hospital. One hundred one women were premenopau sal with regular menstrual cycles; 185 women were perimenopausal with irregular periods or with absence of menstruation for <11 months; 160 women had spontaneous menopause with at least 12 months of amenorrhea; 67 women had a surgical menopause (hysterectomy with bilateral oophor ectomy) prior to which they had regular menstruation. To minimize the age bias on BMD, all postmenopausal patients were selected to have the age range at menopause corresponding with the chronological age range (45-53 years) of premenopausal women used as reference. Moreover, to evaluate the influence of time since menopause on BMD, all postmenopau sal women were stratified in five categories according to time lapsed since their last menses or oophorectomy. BMD values of spontaneous and surgical menopause do not appear to differ significantly (0.908 +/- 0 .146 and 0.885 +/- 0.129 g/cm(2), mean +/- SD), However, the differenc e between the menopausal groups becomes evident when BMD results take into account the interval since menopause. After 61-144 months of amen orrhea, women who had undergone spontaneous menopause had a cumulative bone loss of 21.8% in comparison with premenopausal BMD, whereas wome n who had undergone surgical menopause had a bone loss of 25.8%, The y early percentage of bone loss values of surgical menopause (ranging fr om 3.72 to 7.93) settled to similar to 1% per year after 5 years from oophorectomy, whereas the percentage values of spontaneous menopause ( ranging from 1.75 to 4.65) settled to 1% per year after 3 years since the last menses. The difference between bone loss rates of spontaneous and surgical menopause, evaluated by comparison of regression coeffic ients (-0.027 and -0.051, respectively) of linear regressions of BMD v alues on time since menopause, was statistically significant (p much l ess than 0.001). Odds ratio (OR) of osteopenia (as T score, less than or equal to -1) was significantly higher in surgical menopause (OR, 10 .36; CI, 24.69-4.34) compared with spontaneous menopause (OR, 7.11; CI , 14.73-3.43). Our data support the evidence that women undergoing bil ateral oophorectomy while still menstruating are at a higher risk of o steopenia than women undergoing menopause spontaneously.