Outdoor temperature and circulating sodium in children with acute gastroenteritis

Background: Dysnatremias are frequent in acute gastroenteritis. High outdoor temperatures have been associated with hyponatremia in both adults and the elderly, but no data are available among children with gastroenteritis. Methods: Children <10 years of age admitted to the emergency department of the Policlinico Hospital, Milan (Italy) between 2009 and 2019 with acute moderate-severe gastroenteritis were enrolled. The association between hyponatremia (sodium < 135 mmol/L) and daily mean levels of temperature or apparent temperature from day of admission up to 14 days before was analyzed by multivariable logistic regression models. Results: In 202 included children (46% females), we observed an increased risk of hyponatremia per unit increase in outdoor temperature of the sixth, eighth and ninth day before admission [Odds Ratio = 1.24 (95% Confidence Interval: 1.04–1.47), 1.14 (1.01–1.28), and 1.14 (1.01–1.28), respectively]. Analyses considering average temperature levels of the ten days preceding admission returned similar findings as well as those on apparent temperature. Conclusions: Our data suggest the existence of an association between outdoor temperature and circulating sodium levels in children with acute gastroenteritis. The role of meteorological conditions on electrolyte imbalance should be further explored in the context of climate change. Impact: The role of meteorological variables in the development of dysnatremias has been demonstrated in children and adolescents with cystic fibrosis.This study shows for the first time that higher outdoor temperatures are associated with a higher risk of hyponatremia in children with gastroenteritis.In the context of climate change, the role of external climate conditions on the risk of electrolyte imbalance in children should be more and more considered and explored in future studies.