title: Mortality after hospitalization with mild, moderate, and severe hyponatremia.
abstract: BACKGROUND
  Hyponatremia is the most common electrolyte abnormality in hospitalized individuals.
  
  
  METHODS
  To investigate the association between serum sodium concentration and mortality, we conducted a prospective cohort study of 98,411 adults hospitalized between 2000 and 2003 at 2 teaching hospitals in Boston, Massachusetts. The main outcome measures were in-hospital, 1-year, and 5-year mortality. Multivariable logistic regression and Cox proportional hazards models were used to compare outcomes in patients with varying degrees of hyponatremia against those with normal serum sodium concentration.
  
  
  RESULTS
  Hyponatremia (serum sodium concentration <135 mEq/L) was observed in 14.5% of patients on initial measurement. Compared with patients with normonatremia (135-144 mEq/L), those with hyponatremia were older (67.0 vs 63.1 years, P <.001) and had more comorbid conditions (mean Deyo-Charlson Index 1.9 vs 1.4, P <.001). In multivariable-adjusted models, patients with hyponatremia had an increased risk of death in hospital (odds ratio 1.47, 95% confidence interval [CI], 1.33-1.62), at 1 year (hazard ratio 1.38, 95% CI, 1.32-1.46), and at 5 years (hazard ratio 1.25, 95% CI, 1.21-1.30). The increased risk of death was evident even in those with mild hyponatremia (130-134 mEq/L; odds ratio 1.37, 95% CI, 1.23-1.52). The relationship between hyponatremia and mortality was pronounced in patients admitted with cardiovascular disease, metastatic cancer, and those admitted for procedures related to the musculoskeletal system. Resolution of hyponatremia during hospitalization attenuated the increased mortality risk conferred by hyponatremia.
  
  
  CONCLUSIONS
  Hyponatremia, even when mild, is associated with increased mortality.
authors.affiliation: Renal Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass. 02115, USA. swaikar@partners.org
authors.forename: Sushrut S
authors.initials: SS
authors.lastname: Waikar
authors.forename: David B
authors.initials: DB
authors.lastname: Mount
authors.forename: Gary C
authors.initials: GC
authors.lastname: Curhan
mesh_terms: D000368:Aged; D005260:Female; D006760:Hospitalization; D006801:Humans; D007010:Hyponatremia / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012720:Severity of Illness Index; D013997:Time Factors
references.citation: QJM. 2006 Aug;99(8):505-11
references.pmid: 16861720
references.citation: Lancet. 2008 May 10;371(9624):1624-32
references.pmid: 18468546
references.citation: Am J Cardiol. 2007 Aug 1;100(3):406-8
references.pmid: 17659918
references.citation: Am J Med. 1987 Nov;83(5):905-8
references.pmid: 3674097
references.citation: J Clin Endocrinol Metab. 2002 Mar;87(3):978-82
references.pmid: 11889147
references.citation: Gut. 2007 Sep;56(9):1283-90
references.pmid: 17452425
references.citation: Am J Kidney Dis. 2005 Aug;46(2):225-32
references.pmid: 16112040
references.citation: N Engl J Med. 2008 Sep 4;359(10):1018-26
references.pmid: 18768945
references.citation: Curr Med Res Opin. 2008 Jun;24(6):1601-8
references.pmid: 18426691
references.citation: Hepatology. 2005 Jan;41(1):32-9
references.pmid: 15690479
references.citation: Am J Med. 1999 Apr;106(4):399-403
references.pmid: 10225241
references.citation: Med Care. 2004 Apr;42(4):355-60
references.pmid: 15076812
references.citation: Am Heart J. 2004 Jul;148(1):99-104
references.pmid: 15215798
references.citation: Am J Med. 1995 Oct;99(4):348-55
references.pmid: 7573088
references.citation: Am J Med Qual. 2005 Nov-Dec;20(6):319-28
references.pmid: 16280395
references.citation: Am J Med. 2006 Jul;119(7 Suppl 1):S30-5
references.pmid: 16843082
references.citation: J Clin Epidemiol. 1992 Jun;45(6):613-9
references.pmid: 1607900
references.citation: Ann Intern Med. 2004 Nov 16;141(10):745-52
references.pmid: 15545674
references.citation: Clin Endocrinol (Oxf). 2006 Aug;65(2):246-9
references.pmid: 16886968
references.citation: J Am Coll Cardiol. 2008 Jul 29;52(5):347-56
references.pmid: 18652942
references.citation: Clin J Am Soc Nephrol. 2008 Jul;3(4):1175-84
references.pmid: 18434618
references.citation: J Am Soc Nephrol. 2006 Jun;17(6):1688-94
references.pmid: 16641149
references.citation: Ann Intern Med. 1985 Feb;102(2):164-8
references.pmid: 3966753
references.citation: Med Care. 2004 Aug;42(8):801-9
references.pmid: 15258482
references.citation: Arch Intern Med. 2006 Apr 10;166(7):781-6
references.pmid: 16606816
references.citation: Scott Med J. 2002 Oct;47(5):115-6
references.pmid: 12469566
references.citation: JAMA. 2007 Jan 3;297(1):71-6
references.pmid: 17200477
references.citation: Med Care. 2007 Aug;45(8):789-805
references.pmid: 17667314
references.citation: Int J Clin Pract. 2009 May;63(5):751-6
references.pmid: 19402210
references.citation: Liver Transpl. 2005 Mar;11(3):336-43
references.pmid: 15719386
references.citation: JAMA. 2003 Nov 19;290(19):2581-7
references.pmid: 14625335
references.citation: Hepatology. 2004 Oct;40(4):802-10
references.pmid: 15382176
references.citation: Am J Public Health. 1983 Nov;73(11):1270-4
references.pmid: 6625030
references.citation: N Engl J Med. 2003 Apr 17;348(16):1546-54
references.pmid: 12700374
references.citation: Eur Heart J. 2008 Feb;29(3):339-47
references.pmid: 18156618
references.citation: Am J Med. 2006 Jan;119(1):71.e1-8
references.pmid: 16431193
references.citation: Eur J Heart Fail. 2008 Feb;10(2):196-200
references.pmid: 18279774
references.citation: Arch Intern Med. 2002 Feb 11;162(3):323-8
references.pmid: 11822925
references.citation: Support Care Cancer. 2000 May;8(3):192-7
references.pmid: 10789959
references.citation: Anticancer Res. 2001 Mar-Apr;21(2B):1379-83
references.pmid: 11396218
references.citation: N Engl J Med. 1973 Oct 18;289(16):843-4
references.pmid: 4763428
references.citation: Med Care. 2005 Feb;43(2):182-8
references.pmid: 15655432
references.citation: BMC Pulm Med. 2008 Aug 18;8:16
references.pmid: 18710521
references.citation: Am J Med. 2004 Aug 15;117(4):242-8
references.pmid: 15308433
references.citation: Am J Nephrol. 2007;27(2):184-90
references.pmid: 17356253