biostudies-literatureUnknown99(1)Yokota K<h4>Background</h4>We examined the underlying mechanisms of whether hyponatremia could be induced by hypotonic solution administration after the postoperative invasive phase (POIP).<h4>Methods</h4>We included patients who had undergone surgery with expected oral feeding resumption after postoperative day (POD) 3. In this open-label, randomized controlled trial, 100 patients were assigned to three groups by sodium concentrations ([Na]) used for maintenance infusions: 136 mEq/L (ISO) (n = 34), 68 mEq/L (HYPO) (n = 33), and 34 mEq/L (exHYPO) (n = 33). Potassium (20 mEq/L) and glucose (60 g/L) were added to each infusion. Ringer's solution was used in all groups for the first 12 h postoperatively, then switched to a maintenance solution. Blood samples were drawn and evaluated on POD 3.<h4>ResuPediatric research263-269https://www.ebi.ac.uk/biostudies/studies/S-EPMC12920089biostudies-literatureHyponatremia after pediatric surgery: Randomized trial of fluid composition on antidiuretic hormone response.PMC12920089Amano HNishiwaki KSumida WHinoki ANangaku MTainaka THirai TAndo MUchida HShirota CKuwatsuka YYokota KMakita SManaka KfalseHyponatremia after pediatric surgery: Randomized trial of fluid composition on antidiuretic hormone response.<h4>Background</h4>We examined the underlying mechanisms of whether hyponatremia could be induced by hypotonic solution administration after the postoperative invasive phase (POIP).<h4>Methods</h4>We included patients who had undergone surgery with expected oral feeding resumption after postoperative day (POD) 3. In this open-label, randomized controlled trial, 100 patients were assigned to three groups by sodium concentrations ([Na]) used for maintenance infusions: 136 mEq/L (ISO) (n = 34), 68 mEq/L (HYPO) (n = 33), and 34 mEq/L (exHYPO) (n = 33). Potassium (20 mEq/L) and glucose (60 g/L) were added to each infusion. Ringer's solution was used in all groups for the first 12 h postoperatively, then switched to a maintenance solution. Blood samples were drawn and evaluated on POD 3.<h4>Resu2026-01-01T00:00:00Z2026 Jan2026-07-16T13:00:53.839Z2026-07-09T10:56:30.765ZS-EPMC129200894039966010.1038/s41390-025-04124-8