Endogenous cortisol and sex steroids in patients with osteoporotic spinal fractures

Vertebral fractures due to osteoporosis commonly occur in postmenopausal women. Levels of cortisol and sex steroids in the circulation vary among older women. It has been suggested that this variation may contribute to the occurrence of osteoporotic fractures in some subjects but not others. To examine this, 30 patients with osteoporotic spinal fractures were compared to an equal number of controls matched to the patients for age and years since menopause. All subjects had intact ovaries and had not taken estrogen replacement therapy for more than 3 months during their entire lifetime. Spinal bone mineral density determined by dual photon absorptiometry was significantly lower (P less than .01) in the fraction group (0.75 +/- 0.03 g/cm2) than in the controls (1.0 +/- 0.03 g/cm2). No significant differences in body habitus or cortisol and sex steroid levels (both total and free) were found, with the exception of total estradiol levels, which were 16% higher in the fracture patients. This difference was presumably coincidental as there was no difference of free estradiol levels between groups. It is concluded that factors other than the differences of endogenous cortisol and sex steroid levels present in these postmenopausal women were responsible for the reduced bone mineral density of the spine observed in the fracture patients.