title: Is the sodium level per se related to mortality in hospitalized patients with severe hyponatremia?
abstract: BACKGROUND
  Severe hyponatremia is a serious medical condition that is associated with morbidity and mortality. Controversy still exists regarding the prevalence, cause and mortality of hyponatremia.
  
  
  METHODS
  Of the hyponatremic patients, we studied 116 severe hyponatremic patients. Severe hyponatremia was defined as a serum sodium concentration equal to or less than 120 mmol/l at least twice.
  
  
  RESULTS
  The mean age of the patients was 67.3 ± 14.9 years. The mean sodium level at the time of diagnosis was 114.9 ± 5.2 mmol/l. Normal extracelluar fluid volume (ECFV) was reported in 44 patients (37.9%). 24 (20.7%) of 44 patients were diagnosed with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Excess ECFV and depleted ECFV were reported in 37 (31.9%) and 18 patients (15.5%), respectively. In 17 patients (14.7%), the exact causes could not be determined due to incomplete laboratory studies. On the univariate analysis, age (p = 0.030), the Charlson's risk index (p = 0.000) and the correction rate (p = 0.000) were associated with the 1-year survival. The time of onset (p = 0.051) and the initial serum sodium level (p = 0.986) were not associated with the 1-year survival. On the multivariate analysis, the Charlson's risk index (p = 0.003) and the correction rate (p = 0.033) were independently associated with 1-year survival.
  
  
  CONCLUSIONS
  This study showed that the sodium level per se is not related to mortality, but a higher Charlson's risk index and a slow rate of correcting the sodium are related with mortality. For improving the survival of patients with severe hyponatremia, we should pay more attention to correct the underlying comorbidity.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Seok Hui
authors.initials: SH
authors.lastname: Kang
authors.forename: Hyung Wook
authors.initials: HW
authors.lastname: Kim
authors.forename: So Young
authors.initials: SY
authors.lastname: Lee
authors.forename: In O
authors.initials: IO
authors.lastname: Sun
authors.forename: Hyeon Seok
authors.initials: HS
authors.lastname: Hwang
authors.forename: Sun Ryoung
authors.initials: SR
authors.lastname: Choi
authors.forename: Byung Ha
authors.initials: BH
authors.lastname: Chung
authors.forename: Hun Suk
authors.initials: HS
authors.lastname: Park
authors.forename: Cheol Whee
authors.initials: CW
authors.lastname: Park
authors.forename: Chul Woo
authors.initials: CW
authors.lastname: Yang
authors.forename: Yong Soo
authors.initials: YS
authors.lastname: Kim
authors.forename: Bum Soon
authors.initials: BS
authors.lastname: Choi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D016009:Chi-Square Distribution; D015897:Comorbidity; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007010:Hyponatremia / Q000097:blood* / Q000175:diagnosis / Q000209:etiology / Q000401:mortality* / Q000628:therapy; D007297:Inpatients / Q000706:statistics & numerical data*; D053208:Kaplan-Meier Estimate; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D012964:Sodium / Q000097:blood*; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D012964:Sodium