[Amenorrhea in young women]

The adolescent is an important period in which the peak bone mass is acquired. A sufficient attainment of peak bone mass is important as well as a prevention of bone loss in postmenopausal period in order to prevent osteoporosis in future. It is well known that the estrogen deficiency is at risk of developing osteopenia. Anorexia nervosa, excessive exercises, Turner's syndrome and premature ovarian failure are leading causes of prolonged amenorrhea in young women. However, estrogen deficiency is not the only cause of low bone mass in these women. Although hormone replacement therapy is effective to increase bone mineral density in these women, management of amenorrhea should be individualized according to the status of bone metabolism.