Caused by defect in water excretion. Renal failure and nephrotic syndrome. Cirrhosis and ascites. Clinical situation and underlying disease are key to cause. Generally will manifest edema from underlying cause.
Postoperative hyponatremia is more common and more severe in menstruating females.
Diagnosis of dilutional or hypervolemic hyponatremia. Isovolemic or hypervolemic without edema. May find inciting factor. Fluid restriction to 1 liter per day. Combined water and sodium loss.