副甲状腺機能低下症の病態生理

Parathyroid Hormone. Pathophysiology of Hypoparathyroidism.

　広義の副甲状腺機能低下症は副甲状腺ホルモン（PTH）の欠乏あるいは標的臓器におけるPTH不応性によって引き起こされ，低カルシウム血症および高リン血症を示す。PTH欠乏は副甲状腺の破壊や発生異常，あるいはPTHの産生・分泌障害に基づく。一方，標的臓器におけるPTH不応性はシグナル伝達の障害が原因であり，偽性副甲状腺機能低下症やBlomstrand lethal chondrodysplasia，acrodysostosisなどが含まれる。 　近年，遺伝性副甲状腺機能低下症の病因の同定が進んでおり，診断のためには必要に応じて遺伝子検査が考慮される。

　Hypoparathyroidism in a broad sense is caused by a parathyroid hormone（PTH）deficiency or resistance, leading to hypocalcemia and hyperphosphatemia. PTH deficiency can be result from destruction or hypoplasia/agenesis of the parathyroid gland, or the impaired synthesis or secretion of PTH. On the other hand, PTH resistance is based on the disrupted transduction of its signaling and includes pseudohypoparathyroidism, Blomstrand lethal chondrodysplasia and acrodysostosis. There has been a substantial progress in the identification of the pathogenesis for the inherited hypoparathyroidism, and genetic tests for diagnosis are considered when necessary.