若年性・遅発性男性性腺機能低下症と骨粗鬆症

Osteoporosis in Men. Early-onset and late-onset male hypogonadotropic hypogonadism and osteoporosis.

　血中テストステロン濃度が低値となる男性性腺機能低下症には，若年性と遅発性がある。前者は間脳－下垂体－精巣系の調節機構が傷害された２次性精巣機能低下症と，クラインフェルター症候群に代表される原発性精巣機能低下症がある。遅発性男性性腺機能低下症は，近年LOH症候群という概念でまとめられた症候群で，血中のbioavailable testosteroneの低下を原因とする疾患である。これらの疾患における骨健康に関して，血中テストステロンとの関係を概説した。

　Hypogonadism is classified into two major clinical entities, namely early-onset hypogonadism and late-onset hypogonadism. The former is characterized by the malfunction of hypothalamo-pituitary-gonadal（testicular）axis or by the primary hypofunction of testes（e.g. Klinefelter's syndrome）. The latter is summarized as LOH syndrome which is attributed to the dropped level of bioavailable testosterone. In these diseases testosterone is the key molecule which may cause various symptoms relating not only to physical health but also to mental or psychologic health. In this review issues concerning bone health in these disease are described.