[Sex steroid hormones and bone].

Based on the progress of researches in bone biology field, it has been clarified that bone metabolism can be regulated by complex network between various tissues and organs. Among them, sex steroid hormones, including estrogen and androgen, are known as one of the players in bone metabolism. Sex steroid hormones play crucial roles for maintenance of bone tissue because bone mass can be decreased by deficiencies of sex steroid hormones. Also, sex steroid hormones replacement therapies, which have various adverse effects, can rescue bone loss and prevent fractures. This review introduces the direct and indirect regulatory mechanism of sex steroid hormones for bone metabolism.