By recognizing the cumulative actions of PTH and its fragments and taking into consideration the combined effects of the direct action of teriparatide itself and changes to endogenous PTH(1–84), it may be possible to elucidate the yet unknown action of PTH in osteoporosis, thereby facilitating the development of an ideal dosing schedule for teriparatide administration. The gene discussed is PTH; the disease is osteoporosis.