Alendronate and teparatide, recombinant human PTH (1-34) are available treatment for osteoporosis in postmenopausal women. They act through opposite mechanisms of action. Alendronate reduces the remodeling of bone and thus increases secondary mineralization without any change in the amount of bone. Teriparatide, 20 micrograms/day, a bone forming agent would increase the amount of bone through two mechanisms, modeling--formation without resorption, and remodeling--resorption then formation with formation higher than resorption. Theses effects are present at the sixth month.