Systemic insulin-like growth factor-I, insulin and vitamin D status in relation to age-associated bone loss in women.

This cross-sectional study, performed on 146 healthy (n = 64) or osteoporotic but otherwise normal (n = 82) pre- (n = 38) or post-menopausal (n = 108) female subjects, analyzed the relationships between bone mineral density (BMD) (measured by dual-energy X-ray absorptiometry), parameters of bone remodelling, indices of calcium homeostasis and systemic IGF-I or insulin levels against a background of natural aging. BMD (g/cm(2)) at the hip correlated to serum IGF-I concentration (r = 0.207, p < 0.05), as well as to insulin levels (r = 0.241, p < 0.01), while BMD at the spine correlated only to IGF-I levels (r = 0.173, p < 0.05). After adjustment for age, body mass index, serum PTH, vitamin D status and calcitonin levels, neither IGF-I nor insulin levels could be significantly related to BMD at the spine or hip. On the other hand, 25-OH vitamin D(3) was found to be an important predictor of BMD at the hip (beta = 0.1686, p = 0.0437). In conclusion, this study failed to demonstrate a predictive importance of insulin-IGF-I axis to the development of bone mass. Instead, a significant predictive value to BMD at the hip was documented for serum 25-OH vitamin D(3).