Postmenopausal osteoporosis is more related to hormonal aberrations than to lifestyle factors

OBJECTIVE Serum insulin-like growth factor-1 (IGF-1) decreases with increas ing age and this process is more pronounced in women after the menopause in parallel with the increasing prevalence of osteoporosis. This study was de signed to compare IGF-1 concentrations, vitamin D, intact parathyroid hormo ne (PTH) and lifestyle factors in postmenopausal, osteoporotic women with a nd without oestrogen replacement therapy (HRT), with an age-matched random population sample of women. DESIGN Case control study, PATIENTS Postmenopausal, osteoporotic women, n=128, mean age 59 +/- 6 years , were compared with a female random population sample matched for age, n=2 27, mean age 59 +/- 5 years, from the WHO MONICA Project, Goteborg, Sweden. Osteoporotic fractures had occurred in 56% of the patients compared with 4 % of the controls (P < 0.001). MEASUREMENTS Anthropometry, occupation, smoking habits, physical activity, blood pressure, IGF-1, vitamin D, intact PTH, blood lipids. RESULTS There were no differences in occupational class, current or previou s smoking habits, degree of physical activity during occupational or leisur e time between the patients and controls. Osteoporotic women had lower body weight and body mass index than the controls (P < 0.001). Height, waist/hi p ratio and osteocalcin were similar. 25(OH) vitamin D and 1,25(OH)(2) vita min D were lower (P < 0.05 and P < 0.01, respectively), PTH was higher (P < 0.001) and IGF-1 lower (P < 0.01) in osteoporotic women compared with the controls. IGF-1 was lower (P < 0.05), in spite of similar bone mineral dens ity, in osteoporotic women without HRT than in those with HRT, who had IGF- 1 concentrations similar to those of the population sample, of whom fewer t han 10% had HRT, Among patients, IGF-1 did not correlate with serum oestrad iol or bone mineral density. PTH correlated negatively to bone mineral dens ity at the femoral site (r= -0.29; P= 0.003). CONCLUSION Osteoporosis in postmenopausal women is more related to hormonal aberrations than to lifestyle factors.