Brief Review of the Literature on Hyponatremia, Death, and Injury in Endurance Athletes

By John Henry Dreyfuss, MDalert staff.
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The Myths of Dehydration and Heat Illnesses

  • The primary cause of hyponatremia in athletes is drinking too much water.
  • The incidence of hyponatremia appears to be between 13% and 15% among endurance athletes.
  • Gender and the duration of athletic activity appear to be predictors of the incidence of hyponatremia.
  • Sodium supplementation has no effect on the occurrence of hyponatremia.
  • There seems to not be a single case of death resulting from sports-related dehydration in the medical literature.

Following is a brief review of the literature on exercise-associated hyponatremia. Please see the article based on these studies here.

  1. Hyponatremia among Triathletes in the Ironman European Championship. N Engl J Med. 2016; 374:997-998.

  2. Exercise-associated hyponatremic encephalopathy and exertional heatstroke in a soldier: High rates of fluid intake during exercise caused rather than prevented a fatal outcome. Nolte HW, Hew-Butler T, Noakes TD, Duvenage CS. Phys Sportsmed. 2015 Feb;43(1):93-8.

  3. Efficacy of oral versus intravenous hypertonic saline in runners with hyponatremia. Owen BE, Rogers IR, Hoffman MD, Stuempfle KJ, Lewis D, Fogard K, Verbalis JG, Hew-Butler T. J Sci Med Sport. 2014 Sep;17(5):457-62
  4. Medical complications and deaths in 21 and 56 km road race runners: a 4-year prospective study in 65 865 runners--SAFER study I. Schwabe K, Schwellnus M, Derman W, Swanevelder S, Jordaan E. Br J Sports Med. 2014 Jun;48(11):912-8.
  5. Sodium Supplementation and Exercise-Associated Hyponatremia during Prolonged Exercise. Hoffman MD, Stuempfle KJ. Med Sci Sports Exerc. 2014 Dec 29. 
  6. Water and sodium intake habits and status of ultra-endurance runners during a multi-stage ultra-marathon conducted in a hot ambient environment: an observational field based study. Costa RJ, Teixeira A, Rama L, Swancott AJ, Hardy LD, Lee B, Camões-Costa V, Gill S, Waterman JP, Freeth EC, Barrett E, Hankey J, Marczak S, Valero-Burgos E, Scheer V, Murray A, Thake CD. Nutr J. 2013 Jan 15;12:13
  7. Avoid adding insult to injury - correct management of sick female endurance athletes. Hew-Butler TD, Boulter J, Bhorat R, Noakes TD. S Afr Med J. 2012 Oct 22;102(12):927-30
  8. The incidence of exercise-associated hyponatraemia in the London marathon. Kipps C, Sharma S, Pedoe DT. Br J Sports Med. 2011 Jan;45(1):14-9.  
  9. Prevalence of hyponatremia, renal dysfunction, and other electrolyte abnormalities among runners before and after completing a marathon or half marathon. Mohseni M, Silvers S, McNeil R, Diehl N, Vadeboncoeur T, Taylor W, Shapiro S, Roth J, Mahoney S. Sports Health. 2011 Mar;3(2):145-51
  10. Acute water intoxication during military urine drug screening. Tilley MA, Cotant CL. Mil Med. 2011 Apr;176(4):451-3
  11. An intervention study of oral versus intravenous hypertonic saline administration in ultramarathon runners with exercise-associated hyponatremia: a preliminary randomized trial. Rogers IR, Hook G, Stuempfle KJ, Hoffman MD, Hew-Butler T. Clin J Sport Med. 2011 May;21(3):200-3.
  12. Do male 100-km ultra-marathoners overdrink? Knechtle B, Knechtle P, Rosemann T. Int J Sports Physiol Perform. 2011 Jun;6(2):195-207
  13. Beliefs about hydration and physiology drive drinking behaviours in runners. Winger JM, Dugas JP, Dugas LR. Br J Sports Med. 2011 Jun;45(8):646-9.
  14. Lack of awareness of fluid needs among participants at a Midwest marathon. Brown S, Chiampas G, Jaworski C, Passe D. Sports Health. 2011 Sep;3(5):451-4
  15. Can changes in body mass and total body water accurately predict hyponatremia after a 161-km running race? Lebus DK, Casazza GA, Hoffman MD, Van Loan MD. Clin J Sport Med. 2010 May;20(3):193-9.
  16. Exercise-associated hyponatremia. Rosner MH. Semin Nephrol. 2009 May;29(3):271-81. doi: 10.1016/j.semnephrol.2009.03.001. 
  17. Exertional dysnatremia in collapsed marathon runners: a critical role for point-of-care testing to guide appropriate therapy. Siegel AJ, d'Hemecourt P, Adner MM, Shirey T, Brown JL, Lewandrowski KB. Am J Clin Pathol. 2009 Sep;132(3):336-40. doi: 10.1309/AJCP30OGLSLWLEIY. 
  18. Risk factors for exercise-associated hyponatremia in non-elite marathon runners. Chorley J, Cianca J, Divine J. Clin J Sport Med. 2007 Nov;17(6):471-7.
  19. Marathon related death due to brainstem herniation in rehydration-related hyponatraemia: a case report. Petzold A, Keir G, Appleby I. J Med Case Rep. 2007 Dec 28;1:186. doi: 10.1186/1752-1947-1-186.  (See Figure.) 
  20. Hyponatremia among runners in the Boston Marathon. Almond CS, Shin AY, Fortescue EB, Mannix RC, Wypij D, Binstadt BA, Duncan CN, Olson DP, Salerno AE, Newburger JW, Greenes DS. N Engl J Med. 2005 Apr 14;352(15):1550-6.
  21. Death from hyponatremia as a result of acute water intoxication in an Army basic trainee. Garigan TP, Ristedt DE. Mil Med. 1999 Mar;164(3):234-8.

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