Management of Hyponatremia..

Five days after an uneventful cholecystectomy, an asymptomatic middle-aged woman is found to have a serum sodium level of 120 meq/L.
Proper management would be
a. Administration of hypertonic saline solution
b. Restriction of free water
c. Plasma ultrafiltration
d. Hemodialysis
e. Aggressive diuresis with furosemide

Answer:
b. Restriction of free water

Discussion: Acute severe hyponatremia sometimes occurs following elective surgical procedures. It is usually the result of the combination of appropriate postoperative stimulation of antidiuretic hormone and injudicious administration of excess free water in the first few postoperative days.
Totally sodium-free intravenous fluids (e.g., dextrose and water) should be given with great caution postoperatively, since occasionally the resulting hyponatremia can be associated with sudden death from a flaccid heart or with severe permanent brain damage.
The condition is usually best treated by withholding free water and allowing the patient to reequilibrate spontaneously.
At levels below 115 meq/L, seizures or mental obtundation may mandate treatment with hypertonic sodium solutions. This must be done with extreme care because the risk of fluid overload with acute pulmonary or cerebral edema is high.