Abstract: Objective To study the incidence of hyponatremia in hospitalized children after maintenance solution treatment and analyze the influencing factors on the occurrence of hyponatremia in children. Methods A prospective and observational study was conducted to include children hospitalized in the General Hospital of Southern Theater Command from January 2021 to January 2023 who needed at least 24 hours of intravenous maintenance solution with more than half of their physiological requirements. Baseline data, clinical indicators, and test indicators were collected to analyze the incidence of hyponatremia and its influencing factors. Results A total of 111 children were enrolled, including 40 cases of central nervous system disease, 14 cases of respiratory disease, 25 cases of gastrointestinal disease, 20 cases of hematological tumor diseases, and 12 cases of sepsis or systemic inflammatory response syndrome. The incidence of hyponatremia was 27.9% （31/111）, with mild hyponatremia being 23.4% （26/111） and moderate hyponatremia being 4.5% （5/111）。 Multivariate Logistic regression analysis showed that higher copeptin level （medium level OR=146.528, high level OR=524.775） and severity or critical ill state （OR=7.732） were risk factors for hyponatremia, while higher total solution tension （1/2-3/4 tension OR=0.014, ≥3/4 tension OR=0.004） was a protective factor for hyponatremia （all P<0.05）。 The contingency table analysis showed that the incidence of hyponatremia was lower in children with low level of copeptin or higher level of maintenance solution tension （≥1/2 tension）, which were 1.8% （1/56） and 6.3% （2/32）, respectively. Conclusion The incidence of hyponatremia is high in hospitalized children who require maintenance solution treatment for more than 24 hours, and the use of higher tension maintenance solution （total solution tension ≥1/2） is recommended, especially for children with high copeptin levels.

Key words: Children, Hyponatremia, Solution tension, Antidiuretic hormone, Copeptin