女性のエストロゲン/アンドロゲンバランスと骨・カルシウム代謝

Calcium and bone metabolism across women's life stages. Bone metabolism and estrogen/androgen balance in women.

　エストロゲン（E）とともにアンドロゲンも女性の身体的，精神的，性的な面で役割を果たしており，骨の健康を考えた場合，アンドロゲンの作用も考慮すべきである。アンドロゲン受容体は骨芽細胞，破骨細胞ともに存在し，テストステロン（T）は，アンドロゲン受容体を介した作用やアロマターゼによって変換されたEを介した間接的な作用によって骨形成や骨吸収に影響することが推定される。内因性Tは骨密度との間に正の相関関係があり，骨折発症の減少と関連する可能性がある。外因性に投与されたTによって，E単独群に比べて骨密度の増加がみられるが，多毛，にきび，肝機能障害，脂質異常などの副作用に注意が必要であり，乳房や子宮内膜への影響も注意が必要である。

　Androgen as well as estrogen has physical, psychological and sexual roles in women. The action of androgen on bone health in women is important. The androgen receptor is expressed in osteoblasts and osteocytes but the mechanism has not been clarified in women. It has been reported that endogenous testosterone level was positively correlated with bone mineral density and higher testosterone level might be associated with decrease in bone fractures. Also, it has been reported that bone mineral density in women who received testosterone with estrogen was higher than that in women who received estrogen alone. However, it is important to pay attention to occur adverse effects such as hirsutism, acne, disorder of liver function and dyslipidemia. In addition, occurrence of breast cancer and endometrial cancer should be considered. In postmenopausal women, appropriate range of circulating testosterone level may play favor roles in various tissues.