AVP and portal hypertension: Hyponatremia in chronic liver disease is a condition characterised by increased renal retention of water relative to sodium because of impairment in the clearance of solute-free water, which is frequent in individuals with cirrhosis and portal hypertension.1 Hyponatremia can be caused by a variety of reasons among these patients, the most common of which is increased arginine vasopressin secretion (AVP; also known as antidiuretic hormone, or ADH).