Seasonal variations of hyponatremia in the emergency department: Age-related changes

Study objective: We investigated seasonal prevalence of hyponatremia in the emergency department (ED). Design: A cross-sectional study using clinical chart review. Setting: University Hospital ED, with approximately 28 000 patient visits a year. Type of participants: We reviewed 15 049 patients, subdivided in 2 groups: the adult group consisting of 9822 patients aged between 18 and 64 years old and the elderly group consisting of 5227 patients aged over 65 years presenting to the ED between January 1st, 2014 and December 31st, 2015. Intervention: Emergency patients were evaluated for the presence of hyponatremia by clinical chart review. Measurements and main results: Hyponatremia was defined as a serum sodium level < 135mmol/l. Mean monthly prevalence of hyponatremia was of 3.74 +/- 0.5% in the adult group and it was significantly increased to 10.3 +/- 0.7% in the elderly group (p < 0.05 vs adults). During the summer, hyponatremia prevalence was of 4.14 +/- 0.2% in adult and markedly increased to 12.52 +/- 0.7% (zenith) in elderly patients (p < 0.01 vs adult group; p < 0.05 vs other seasons in elderly group). In the elderly group, we reported a significant correlation between weather temperature and hyponatremia prevalence (r: 0.491; p < 0.05). Conclusion: We observed a major influence of climate on the prevalence of hyponatremia in the elderly in the ED. Decline in renal function, salt loss, reduced salt intake and increased water ingestion could all contribute to developing hyponatremia in elderly patients during the summer. These data could be useful for emergency physicians to prevent hot weather-induced hyponatremia in the elderly. (c) 2017 Published by Elsevier Inc.