[Bone mineral loss due to premenopausal oophorectomy assessed by dual photon absorptiometry]

Although it has been reported that bone mineral loss due to oophorectomy (OPX) occurs mainly in the axial bone, especially in the trabecular bone, there have been no reports on the use of this method for simultaneous total body calcium measurement. Furthermore, the occurrence of bone mineral loss in regional bone mineral density (BMD) after OPX has not been clarified. We investigated whether there is a decrease in regional BMD after OPX, and whether there are regional differences in bone mineral loss following OPX. The BMD was measured by dual photon absorptiometry in 21 premenopausal oophorectomized subjects (mean age: 46.8 +/- 4.0 yr, mean duration after OPX: 48.0 +/- 40.0 months) and 19 age- and body size-matched females. In OPX subjects, the spinal BMD was significantly lower (corresponding to 87.0 +/- 2.4% of control) than those of the cranium, arms and legs (92.1 +/- 2.6, 97.2 +/- 1.2, 95.4 +/- 1.6% respectively). Furthermore the oophorectomized subjects were divided into three groups according to duration after OPX as follows; within 1 (n = 7), 2-5 (n = 7) and over 6 years (n = 7). The spinal BMD had already tended to decrease in the within 1 year group and significantly decreased in the over-6-year group. On the other hand, there were no differences in the within 1 year group in arm and leg BMD compared with the control. However, in the over-6-year group they were significantly decreased. These results suggest that bone mineral loss in oophorectomized subjects occurs mainly in spinal bone, and the degree of bone mineral loss might be different in regional bone.