Goetz TG, Nair N, Shiau S, et al. - Marked deficits are observed in bone microarchitecture among premenopausal women with idiopathic osteoporosis (IOP) but with variable bone remodeling. In researchers’ previous work, those with low tissue-level bone formation rate (BFR) were demonstrated to exhibit less responsiveness to teriparatide and have higher serum IGF-1, a hormone anabolic for osteoblasts and other tissues. Herein, they examined if IOP women with low BFR have higher IGF-1 and paradoxical IGF-1 associations in skeletal and non-skeletal tissues, and if IGF-1 and the related measures are predictive of teriparatide response.

• An ancillary study to a 24 month clinical trial of teriparatide for IOP.

• Participants were premenopausal women with IOP (n = 34).

• In line with observations in other populations, correlation of lower BFR with higher body fat and poorer teriparatide response was evident.

• However, in contrast to other populations, higher IGF-1 was observed in correlation with low BFR, higher body fat, as well as with poorer teriparatide response: inverse correlation was evident between IGF-1 Z-score and BFR at all bone surfaces, whereas IGF-1 Z-score directly linked to central fat and leptin.

• Inverse correlation of IGF-1 was observed with 24 month hip BMD % change.

• Overall there were paradoxical IGF-1 relationships suggesting a possible contribution of abnormal or atypical regulation of bone and fat to osteoporosis mechanisms in premenopausal IOP.