AVP and kidney failure: The underlying pathophysiological mechanisms include age-related impairment in water excretory capacity causing a reduction in GFR [4], concomitant use of diuretics and central nervous system active drugs [4, 5], the syndrome of inappropriate antidiuretic hormone secretion [37] and the presence of other comorbidities such as HF [1, 2], diabetes mellitus [7, 8], kidney failure [9], cirrhosis [6] and others [6].