title: Seasonal variations of hyponatremia in the emergency department: Age-related changes.
abstract: OBJECTIVE
  We investigated seasonal prevalence of hyponatremia in the emergency department (ED).
  
  
  METHODS
  A cross-sectional study using clinical chart review.
  
  
  METHODS
  University Hospital ED, with approximately 28 000 patient visits a year.
  
  
  METHODS
  We reviewed 15 049 patients, subdivided in 2 groups: the adult group consisting of 9822 patients aged between 18 and 64years old and the elderly group consisting of 5227 patients aged over 65years presenting to the ED between January 1st, 2014 and December 31st, 2015.
  
  
  METHODS
  Emergency patients were evaluated for the presence of hyponatremia by clinical chart review.
  
  
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Medical, Surgical, Neurological, Metabolic and Geriatrics Sciences, University of Campania "L. Vanvitelli", Italy. Electronic address: Mauro.giordano@unina2.it.
authors.forename: Mauro
authors.initials: M
authors.lastname: Giordano
authors.affiliation: Department of Medical, Surgical, Neurological, Metabolic and Geriatrics Sciences, University of Campania "L. Vanvitelli", Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Ciarambino
authors.affiliation: Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Castellino
authors.affiliation: Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Malatino
authors.affiliation: Institute for Experimental Medical Research, Oslo University, Oslo, Norway.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cataliotti
authors.affiliation: Department of Medical, Surgical, Neurological, Metabolic and Geriatrics Sciences, University of Campania "L. Vanvitelli", Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Rinaldi
authors.affiliation: Department of Medical, Surgical, Neurological, Metabolic and Geriatrics Sciences, University of Campania "L. Vanvitelli", Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Paolisso
authors.affiliation: Department of Medical, Surgical, Neurological, Metabolic and Geriatrics Sciences, University of Campania "L. Vanvitelli", Italy.
authors.forename: Luigi Elio
authors.initials: LE
authors.lastname: Adinolfi
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D003430:Cross-Sectional Studies; D004232:Diuretics / Q000009:adverse effects; D004632:Emergency Medical Services / Q000706:statistics & numerical data; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D007010:Hyponatremia / Q000453:epidemiology* / Q000517:prevention & control; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012621:Seasons; D055815:Young Adult
chemical_list: D004232:Diuretics