Vasopressin dysregulation and hyponatremia in hospitalized patients.

Hyponatremia, which is often due to dysregulation of arginine vasopressin, occurs frequently in hospitalized patients and is associated with increased morbidity and mortality. Nonosmotic secretion of arginine vasopressin is central to the pathophysiology of hyponatremia in patients with euvolemic hyponatremia (due to, for example, the syndrome of inappropriate secretion of antidiuretic hormone) and those with hypervolemic hyponatremia secondary to congestive heart failure or cirrhosis with ascites. Arginine vasopressin-receptor antagonists, a novel class of agents that block the action of arginine vasopressin on V2 receptors in the renal collecting ducts, may provide specific correction of sodium and water imbalance in hyponatremia by promoting free water clearance while sparing electrolytes (aquaresis). Arginine vasopressin antagonism would treat hyponatremia directly, as opposed to other therapies that do not address the effects of arginine vasopressin dysregulation directly.