title: Hyponatremia at the Emergency Department: a case-control study.
abstract: BACKGROUND
  Hyponatremia (HNA) is a common electrolyte disturbance associated with morbidity and mortality. The aim of this study was to assess incidence and prognosis value of HNA in the Emergency Department (ED).
  
  
  METHODS
  A retrospective observational case-control study has been conducted in the ED during 10 months. Control patients (Na 135-145 mmol/L) were matched, in a 1:1 ratio, on age, gender and month of ED admission with hyponatremic patients (Na<130 mmol/L).
  
  
  RESULTS
  Two hundred fifty-six patients (2.4% of patients with a blood analysis) had HNA among which 166 were matched with 166 normonatremic controls. HNA patients had more often a history of asthma/chronic obstructive pulmonary disease (P=0.002) and solid tumors (P=0.001), received more diuretics (P=0.026), and presented more often with vomiting (P=0.034). Admission to the hospital or to the ICU was more frequent in HNA patients (89% vs. 52%, P<0.001; 13% vs. 3%, P=0.003, respectively). Patients with HNA presented more frequently at least one complication (digestive, septic, respiratory, renal, and cardiovascular) during their hospital/ICU stay (40% vs. 4%, P<0.001). Mortality rate was higher in HNA than in controls (10% vs. 3%, P=0.021). The multivariable conditional logistic regression analysis showed an independent association of HNA with solid tumors (OR=4.12; 95% CI: 1.68 to 10.1) and hospital death (OR=2.90; 95% CI: 1.03 to 8.17).
  
  
  CONCLUSIONS
  HNA was present in 2.4% of patients with a blood analysis and was associated independently with solid tumors and hospital death.
authors.affiliation: Department of Emergency, Erasme University Hospital, Brussels, Belgium - cmelot@ulb.ac.be.
authors.forename: D
authors.initials: D
authors.lastname: Assen A Abouem
authors.forename: F
authors.initials: F
authors.lastname: Vandergheynst
authors.forename: T
authors.initials: T
authors.lastname: Nguyen
authors.forename: F S
authors.initials: FS
authors.lastname: Taccone
authors.forename: C
authors.initials: C
authors.lastname: Melot
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000150:complications / Q000453:epidemiology*; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010343:Patient Admission; D012189:Retrospective Studies