AVP and Hyponatremia: However, using Ringer's solution during the POIP might prevent hyponatremia in HYPO patients.<h4>Registration number</h4>UMIN000029057 ( https://www.umin.ac.jp/ctr/index.htm ).<h4>Date of first registration</h4>01/11/2017 IMPACT: After the postoperative invasive phase, non-osmotic antidiuretic hormone (ADH) secretion due to surgical stress persisted, resulting in an excess ADH state for at least 3 postoperative days (PODs).