Total and Free Estrogens and Androgens in Postmenopausal Women with Hip Fractures*

Abstract

Hip fracture constitutes the most serious complication of postmenopausal osteoporosis. To examine the possible role of circulating estrogen or androgen levels in the development of this type of fracture, 25 patients with hip fractures after minimal trauma were compared to an equal number of controls, matched for age and years since menopause. All were from a retirement community, had intact ovaries, and had not taken estrogen replacement for longer than 3 months during their entire lifetime. Hip fracture patients were found to have a significantly lower (P = 0.031) mean (+/-SE) percent ideal weight (89.4 +/- 2.9%) than controls (100.0 +/- 2.5%). Sex hormone-binding globulin levels were significantly higher (P = 0.004) in patients (6.7 +/- 0.4 X 10-8 M) than in controls (4.9 +/- 0.3 X 10-8 M), resulting in lower concentrations of biologically available estradiol and testosterone. In a subgroup of 12 patients and controls matched for percent ideal weight, differences in sex hormone binding globulin and free testosterone and estradiol levels were no longer statistically significant; however, the difference in the percentage of free testosterone persisted. These data suggest that endogenous sex steroids in their unbound form may play a role in the pathogenesis of postmenopausal hip fractures. The differences in free hormone levels appeared to be influenced by the differences in mean body size of the 2 groups. This factor is known to have an important negative effect on the concentration of sex hormone-binding globulin.