AVP and Hyponatremia: It increases the force and frequency of peristalsis thereby promoting bowel evacuation.12 There are case reports that SPS bowel preparation solutions can cause severe hyponatremia in some patients.11,13 In a study by Cohen CD et al. hyponatremia was assessed in 40 patients before and after colonoscopy in which 7.5% of patients developed hyponatremia after colonoscopy, with a concomitant increase in arginine vasopressin(AVP).14 The release of AVP as a result of volume depletion secondary to bowel preparation has been described as a triggering factor for hyponatremia in this clinical setting.