Age-related bone loss and senile osteoporosis: evidence for both secondary hyperparathyroidism and skeletal growth factor deficiency in the elderly

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

OBJECTIVE

Serum insulin-like growth factor-1 (IGF-1) decreases with increasing age and this process is more pronounced in women after the menopause in parallel with the increasing prevalence of osteoporosis. This study was designed to compare IGF-1 concentrations, vitamin D, intact parathyroid hormone (PTH) and lifestyle factors in postmenopausal, osteoporotic women with and 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 = 227, mean age 59 +/- 5 years, from the WHO MONICA Project, Göteborg, 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 previous smoking habits, degree of physical activity during occupational or leisure time between the patients and controls. Osteoporotic women had lower body weight and body mass index than the controls (P < 0.001). Height, waist/hip ratio and osteocalcin were similar. 25(OH) vitamin D and 1,25(OH)2 vitamin 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 density, 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 than 10% had HRT. Among patients, IGF-1 did not correlate with serum oestradiol or bone mineral density. PTH correlated negatively to bone mineral density 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.