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University of Connecticut Neag School of Education Korey Stringer Institute

Exertional Hyponatremia

Elizabeth M. Ferraro, ATC and Megan A. Barry, ATC

Hyponatremia is a low concentration of sodium in the blood. When it occurs during exercise, it is called exertional hyponatremia. It is mostly seen in athletes, although it can occur to anyone who either consumes more fluid than necessary in a short time or when too much sodium is lost through sweat and not replaced. Hyponatremia doesn’t always occur during exercise. It can occur hours later if sodium lost is not made up after.

Prevention

  • Have a hydration plan in place
  • Record body weight before and after exercise to monitor fluid consumption
  • Know the sweat rate to determine fluid consumption during exercise
  • Know the signs and symptoms of hyponatremia
  • Have an emergency plan in place for dealing with hyponatremia
  • Monitor the duration and intensity of exercise for determining risk of hyponatremia
  • Educate athletes of risks from fluid overload and encourage moderate hydration.
  • Establish individualized hydration protocol based on personal sweat rate and sports dynamic.
  • Consume adequate dietary sodium.
  • Allow 8-14 days of training in the heat for acclimatization.
  • Identify pre-exercise hyponatremia by recording body weight each day

 

Recognition

  • Headache/nausea
  • Vomiting
  • Altered mental status, disorientation, combative behavior
  • Swelling in extremities, bloating
  • Overdrinking
  • Muscular disturbances
  • Lethargy
  • Identify over-hydrated athletes or athletes who limit sodium intake.

 

Assessment

  • Onset of symptoms
  • Assess blood Na+ using portable blood sodium analyzer (<130mmol/L)
  • Inquiry fluid and food consumed and use of NSAIDs
  • Record vitals

 

Differential Diagnosis

  • Exertional Heat Stroke
  • Heat Exhaustion
  • Heat Cramps
  • Rhabdomyolysis
  • Cardiac Condition

 

Treatment

  • Consume oral hypertonic saline (e.g. bouillon) or hypertonic saline IV
  • Consume salty foods such as potato chips, pickles, jerky, or bullion
  • DO NOT provide normal saline solution or fluids
  • Transport to hospital for blood work if symptoms worsen

 

Return to Play

  • Require a physician clearance
  • Measure sweat rate and Na+ concentrations
  • Gradually increase exercise intensity and duration per environmental conditions

 

Recommended Equipment List

  • Hypertonic saline
  • IV equipment
  • Portable blood Na+ analyzer kit
  • AED
  • Salty foods (e.g. bouillon cubes, pretzels, canned soup, and potato chips)
  • Rectal thermometer
  • Blood pressure cuff
  • Stethoscope
  • Stretcher

 

References

  1. Binkley HM, Beckett J, Casa DJ, Kleiner DM, Plummer PE. National Athletic Trainers’ Association position statement: exertional heat illnesses. J Athl Train. 2002;37(3):329-343.
  2. Hew-Butler T, Ayus JC, Kipps C, Maughan RJ, Mettler S, Meeuwisse WH, Page AJ, Peid SA, Rehrer NJ, Roberts WO, Rogers IR, Rosner MH, Siegel AJ, Speedy DB, Stuempfle KJ, Verbalis JG, Weschler LB, Wharam PM. Statement of the second international exercise-associated hyponatremia consensus development conference, New Zealand. Clin J Sport Med. 2008;18(2):111-121.
  3. Casa DJ, Clarkson PM, Roberts WO. American College of Sports Medicine roundtable on hydration and physical activity: consensus statements. Curr Sports Med Rep. 2005;4:115-127.
  4. Casa DJ, Armstrong LE, Hillman SK, Montain SJ, Reiff RV, Rich B, Roberts WO, Stone JA. National Athletic Trainers’ Association position statement: fluid replacement for athletes. J Athl Train. 2000;35(2):212-224.
  5. Armstrong LE, McDermott BP. Exertional hyponatremia. In: Casa DJ, eds. Preventing Sudden Death in Sport and Physical Activity. Sudbury, MA: Jones & Bartlett Learning. 2012:185-199.
  6. Montain SJ, Sawka MN, Wenger CB. Hyponatremia associated with exercise: risk factors and pathogenesis. Exer Sport Sci Rev. 2001;29(3):113-117.