術前後に興味ある水・電解質異常を呈した下垂体卒中の1例

AN INTERESTING CASE OF PITUITARY APOPLEXY SHOWING ABNORMALITY IN WATER-ELECTROLYTE BEFORE AND AFTER SURGERY

　下垂体腺腫の術前，術後に水・電解質異常を呈する症例は時折経験されるが，今回著者らは，入院後下垂体卒中により神経症状が急激に悪化し，術前低Na血症を呈し，術後低張尿ではない多尿を認めた1症例を経験した。水・電解質に影響を与えると思われる内分泌学的検査（ADH, aldosterone, ANP etc．）の結果，術前の低Na血症時のADHは，6.8pg／mlと高値を示し，その診断基準を充足することから，SIADHと考えられた。また，術後の多尿時の検討では，ADHは2.4pg／mlと正常，ANPは140 Pg／mlと異常高値であり，尿比重も1.010以上に保たれており，高ANP血症による多尿と考えられた。高ANP血症による多尿は，比較的尿浸透圧が保たれており，尿崩症とは明らかに異なる病態である。下垂体腺腫術後には，尿崩症の他に，高ANP血症による多尿も念頭におき，水・電解質を管理すべきである。

Cases which present abnormality in water-elec-trolyte before and after operation of pituitary ade-noma are occasionally reported. The authors have encountered a case in which neurological symptoms became aggravated abruptly with pituitary apo-plexy after admission, hyponatremia was noted before operation and polyuria, not hypotonic urine was observed after operation. As a result of an endocrinological examination which may have an influence on water-electrolyte (ADH, aldosterone, ANP, etc.) the ADH level in hyponatremia before operation was high at 6.8 pg/ml ; so, it was taken as SIADH. According to a study at the time of polyuria after operation, the ADH level was nor-mal at 2.4 pg/ml, the ANP level was abnormally high at 140 pg/ml and the specific gravity of the urine was kept at 1.010 or more. So, polyuria was considered due to abnormally increased con-tent of serum ANP. In polyuria due to abnor-mally increased content of serum ANP, the osmotic pressure of the urine is maintained relatively well, which is a clinical feature evidently different from diabetes insipidus. After operation for pituitary adenoma, wate-electrolyte should be controlled with polyuria due to abnormally increased content of serum ANP in addition to diabetes insipidus taken into consideration.