Forteo for the Treatment of Unexplained Osteoporosis in Premenopausal Women

Idiopathic osteoporosis (IOP) is an uncommon disorder in which otherwise healthy young individuals sustain one or more low-trauma fractures. In studies of IOP in men, histomorphometric indices of bone formation are depressed, and affected men respond to PTH(1-34) with robust increases in lumbar spine (LS) bone mineral density (BMD). This is the beginning of the third year of an R01 (AR4989603) investigating the etiology and pathogenesis, as well as the histomorphometric and bone microarchitectural features of IOP in premenopausal women. There is evidence of markedly decreased bone formation and microarchitectural deterioration with decreased mechanical competence/strength. Teriparatide \[PTH(1-34)\] is an anabolic agent that stimulates bone formation and improves bone microarchitecture. Based on findings, the investigators hypothesize that teriparatide will significantly increase BMD and improve microarchitecture in premenopausal women with IOP. This is an open-label study of carefully characterized premenopausal women with IOP who are participating in a NIH-funded study and who have fragility fractures or very low bone density. Participants in the study will receive 18-24 months of teriparatide and the effects on BMD and microstructure, bone mechanical competence, and bone turnover will be assessed. In order to assess whether teriparatide stimulates bone formation to the same extent in women with IOP as it does in normal women, the study will compare the short-term changes (2 and 4 weeks) in biochemical markers of bone formation in response to teriparatide between women with IOP and normal women who are participating in another NIH-funded study as controls.