Exercise-Associated Hyponatremia Clinical Practice Guidelines (2020)

Wilderness Medical Society

This is a quick summary of the guidelines without analysis or commentary. For more information, go directly to the guidelines by clicking the link in the reference.

February 28, 2020

The guideline update on exercise-associated hyponatremia (EAH) was released on February 7, 2020 by the Wilderness Medical Society.[1]


Participants in endurance athletic events or strenuous wilderness activities should focus on avoiding overdrinking during the activity.

Participants should drink according to thirst, or determine an estimation of their individual fluid needs during pre-event training activities (by assessing body weight losses per hour), which limits the potential for weight gain.

Sodium and/or salty snacks should be freely available for consumption along with the appropriate fluid intake, particularly in long, hot events in non–heat acclimatized persons, but this strategy will not prevent EAH when combined with overdrinking.

Prehospital Assessment and Treatment

When available, point-of-care testing should be done on at-risk, symptomatic patients. If unavailable, integrate all the following clinical and historical information into an assessment of the patient’s hydration status, as available:

  • History of fluid intake

  • Food intake

  • Presenting signs and symptoms

  • Body weight if available

  • Urine output

Oral fluid restriction is indicated if EAH from fluid overload is associated with mild symptoms. Hypotonic fluids are contraindicated in suspected EAH.

Oral sodium in hypertonic solutions or foods with high sodium content (salty snacks) may increase serum sodium levels and enhance symptom relief (over fluid restriction) for mild EAH, if tolerated.

Observe patients for at least 60 min after exercise to ensure no decompensation from delayed symptomatic EAH after cessation of exercise.

Intravenous (IV) hypotonic fluids are contraindicated with suspected fluid overload EAH.

If signs and symptoms of encephalopathy (with or without noncardiogenic pulmonary edema) develop and severe EAH is strongly suspected, an IV bolus of 100 mL of hypertonic saline should be administered immediately.

When transferring care, on-site medical personnel should alert receiving caregivers to the potential diagnosis of EAH and the appropriate fluid management (withhold hypotonic fluids).

Acute In-Hospital Treatment of Symptomatic EAH

Oral and IV hypotonic or isotonic hydration should be avoided early in the management of EAH, but may be appropriate in certain clinical contexts once sodium correction has been initiated or hypovolemia is confirmed.

With suspected EAH, and particularly in patients with altered mental status, sodium estimation should be obtained as rapidly as possible after hospital arrival.

A rapid assessment for signs and symptoms of cerebral edema or noncardiogenic pulmonary edema should be done in all patients with possible EAH.

Severe EAH biochemically confirmed or symptomatic EAH should be treated with a 100-mL bolus of IV hypertonic saline, which can be repeated twice at 10-min intervals (3 doses in total) or until improvement of neurologic symptoms, with the aim of acutely increasing serum sodium concentration by about 4 to 5 mmol/L-1 and reversing cerebral edema.

For more information, see Hyponatremia, Pediatric Hyponatremia, and Hyponatremia in Emergency Medicine. For more Clinical Practice Guidelines, please go to Guidelines.


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