AVP and heart failure: Clinically, the causes of hyponatremia include (1) excessive water intake and increase in water content in the body due to abnormal secretion/activity of antidiuretic hormone (ADH); (2) extrarenal sodium depletion through vomiting, diarrhea, or diaphoresis; and (3) increase in reabsorption of water, such as in edema, cirrhosis, and cardiac insufficiency [6].