RESUMO
Postoperative hyponatremia is common clinical problem, which frequently develops in hospitalized patients. We experienced a case of postoperative hyponatremia with mental confusion and nausea after total hysterectomy in an old aged woman. Her mental status became alert and plasma sodium level was corrected after infusing 3% hypertonic saline for 24 hours. Postoperative hyponatremia is usually attributed to several factors: the infusion of excessive amounts of electrolyte-free water and second actions of antidiuretic hormone to prevent excretion of this electrolyte-free water. When hyponatremic encephalopathy develops, postmenopausal women more likely to either have mild symptoms or good response of treatment than menstruant women. The reasons for having much less morbidity among elderly women than menstruant women are thought that the increasement of brain's adaptation against hyponatremia and the absence of inhibition of such adaptation by estrogen. In summary, postoperative hyponatremia can develop in an old aged woman infused with isotonic solution, but can recovered safely with early detection and proper management. Thus, every effort should be made to avoid hyponatremia and measure plasma sodium level frequently in postoperative period. when hyponatremia developed, it needs proper management.