One of the most common causes of hyponatremia is the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) with diagnostic criteria that include sodium (Na) less than 135 mmol/l, increased urine osmolality more than 100 mOsm/kg, with salt and normal fluid intake, euvolemia without signs of hypo or hypervolemia, serum osmolarity less than 275 mOsm/kg, and urine Na more than 40 mEq/L [4]. Here, AVP is linked to Hyponatremia.