Analysis of relationships between sex hormone dynamics and bone metabolism and changes in bone mass in surgically induced menopause

A 3-year follow-up study was performed of bone metabolism and bene changes induced by surgical menopause as a consequence of hysterectomy and oophorectomy (OVX) in 52 nonmenopausal women. We investigated 22 bone parameters and determined seven bone indices as indieators of bone mineral content by dual-energy X-ray absorptiometry (DXA), quantitative computed tomography (QCT), and microdensitometry (MD). The significant correlations between levels of sex hormones and/or bone parameters and bone indices demonstrated that marked sex-steroid deficiency after surgical menopause induced bone uncoupling during high bone turnover and subsequent rapid bone loss in the early period after OVX. Principal component analysis using correlation coefficients suggested a seven-loading-factor matrix composed of bone parameters and a two loading-factor matrix composed of bone indices. Two groups of parameters—estradiol and estriol, and androstenedione together, and luteinizing hormone and follicle-stimulating hormone together—indicated that the rate of bone loss was greater in the trabecular bone than in the cortical bone. Three other groups of parameters—urine calcium, urine hydroxyproline, and serum bone Gla-protein together; serum alkaline phosphatase, serum calcium, and 1,25-dihydroxy-cliolecalciferol [1,25(OH)₂D] together; and plasma tartrateresistant acid phosphatase—indicated that bone uncoupling, with a prevalence of resorption over formation of bone, was greater in trabecular bone than in cortical bone and also that the magnitude and rate of bone loss in the axial vertebrae surpassed those in the appendicular metacarpals after OVX. Two other groups of parameters, namely, trabecular bone mineral density (D_d) and bone mineral content (D_c), both measured by DXA, and bone mineral density (L₂, L₃), measured by QCT, together; and the cortical thickness index (MCI), cortical bone mineral density (GS/D), and the ratio of GSmin/max, measured by MD, indicated that the relative rates of bone reduction at the 3-year follow-up were greater in the axial vertebrae than in the appendicular metacarpals. Thus, bone change in the trabecular bone was associated with rapid loss during the early phase after OVX, whereas that in the cortical bone was slow during the late phase.