高ナトリウム血症を呈した視床下部腫瘍—血漿ADHからみた発症機序の考察

Hypernatremia due to Hypothalamic tumor: ADH response to changes in plasma osmolality

I．はじめに

　視床下部の器質性病変では視床下部症候群hypothala—mic syndromeとよばれる多彩な臨床症状が現れ，その病因としては脳腫瘍が最も多く，そのなかではcranio—pharyngioma，次いでgerminomaが多いとされている．われわれは著明な高ナトリウム血症（以下高Na血症），るいそうなどの視床下部症状で発症した第三脳室近傍のgerminomaと考えられる1例を経験した．高Na血症の原因である浸透圧調節系の障害につき，臨床症状と内分泌学的異常とくに血漿浸透圧に対する血漿抗利尿ホルモン（以下ADH）の反応性の異常の面よりその発症機序について考察を加え報告する．

A case of a patient with the syndrome of chronic hypernatremia and hypodispia due to hypothalamic tumor was studied to evaluate the change of ADH res-ponse to plasma osmolality during the clinical course.

A 23-year-old man was admitted for investigation of anorexia, hypodipsia and gait disturbance. Examination showed memory disturbance and generalized muscle weakness. Investigation showed marked hypernatremia (177mEq/l) and hypopituitarism. Water loading test showed that ADH was not stimulated by hyperosmolal-ity but continued to be secreted at a more or less con-stant level approximating normal basal state.