**3.1 Osteoporosis in women**

Majority of osteoporosis patients are women because of menopause. During the menopausal transition period, levels of estrogen drop, causing a big disruption in the bone remodeling process. This process is a biological event permitting to renew the old bone matrix by resorbing the old one and replacing it with a new one. Specific bone cells are involved in this process, where their behavior is controlled by numerous biochemical substances, including estrogen. Indeed, estrogen stimulates bone formation and inhibits bone resorption; thus, by its drop, bone resorption rate becomes higher, inducing bone loss. Based on this fact, other factors related to hormonal disturbance also induce osteoporosis. For instance, the problem of oligomenorrhea and taking high doses of glucocorticoids may cause the declination of bone density and increase the fracture risk for women [16, 17]. The assessment of osteoporosis in premenopausal women is not based on BMD value alone because of its high dependency to age. Therefore, there are other signs beyond BMD value, like the exposure of glucocorticoid, parathyroidism, hypogonadism, and eating disorder [18], which make osteoporosis diagnosis easier. Moreover, fractures' occurrence in this period can be also an index of postmenopausal osteoporosis in women [19].
