AVP and Hyponatremia: Since AVP release is a primary cause of hyponatremia in cirrhosis, several vasopressin receptor antagonists have been evaluated in treating hyponatremia in patients with cirrhosis/ESLD and other conditions characterized by hypervolemic hyponatremia (e.g., heart failure) or euvolemic hyponatremia (e.g., the syndrome of inappropriate secretion of antidiuretic hormone [SIADH]).