In this study, the investigators would like to analyze the bone mineral density (BMD) , bone turnover makers, and fracture prevention effects of daily teriparatide in Japanese patients under clinical practice. The participants are treated in the investigators hospital, who are under severe osteoporotic condition.

Several determinants were reported to be related to subsequent BMD increase, such as baseline bone turnover markers (BTMs), low BMD at baseline, age, prior treatment, but comprehensive discussion is lacking. Specifically, there analyses were performed fragmentarily.

The main objective of this study is to reveal the determinants of subsequent BMD increase and fracture preventing effect by teriparatide.

Next, in Japan, as the baby boom generation retires, aging and depopulation occur rapidly. As a result, there is a lot of nursing home. But there are few reports concerning to the efficacy of teriparatide treatment in nursing home patients. The second objective is to reveal the efficacy of teriparatide for patients living nursing home, especially BMD changes, bone turnover makers change, and adverse events.

Registry criteria: Patients treated in the investigators hospital using teriparatide. Enrolled patients are severe osteoporosis; more than two previous osteoporotic fractures, low BMD (< young adult mean 65%).

Interventions: blood analyses and dual-energy X-ray absorptiometry (DXA) every 4 months Informed consent: Written informed consent will be obtained. Sample size: Five-hundreds participants

Inclusion Criteria:

• severe osteoporotic patients

Exclusion Criteria:

• cancer, hypercalcemia, etc (i.e. patients who could not use teriparatide)

Osteoporotic patients who admit to our hospital