Age-related changes in insulin-like growth factor I and II in human femoral cortical bone: Lack of correlation with bone mass

The concentration of insulin-like growth factor-I (IGF-I) in human cortical bone declines with age, but the relevance of this decline for cortical bon e turnover and bone mass is unknown, In the present study, we simultaneousl y assessed the concentration of IGF-I and -II in cortical bone matrix and h istomorphometric parameters of bone mass and bone: turnover in 125 samples from the proximal human femur shaft. Bone width decreased by 27% and porosi ty increased by 100% in female, cortical bone between the fourth and the ni nth decade. Similar, but weaker, changes tended to occur in male cortical b one; The concentrations of both IGF species were correlated with the percen tage of osteons undergoing bone remodeling. However, despite age-related de creases:in both IGF species in men and in IGF-I in women, neither of the IG Fs accounted for age-related or age-independent variability in cortical por osity or bone width. In conclusion, these data suggest that the local conce ntrations of IGE-I and -II are: related to cortical bone turnover, In contr ast, our study provides no evidence for a major role of bone matrix IGF I a nd -II as determinants of cortical bone mass in elderly individuals. Whethe r other components of the IGF system may be-stronger determinants of cortic al bone loss remains to be determined. (C) 1999 by Elsevier Science Inc. Al l rights reserved.