Background

Exercise-associated hyponatremia (EAH) is a preventable, acute condition related to recent prolonged physical activity that results in a low level of sodium in the blood (< 135 mEq/L). Symptomatic EAH occurs in less than 1% of endurance athletes, but an incorrect diagnosis and delayed treatment can be fatal.

EAH is often due to overhydration or drinking too much water or diluted fluids and can occur in individuals with impaired urinary water excretion. Other causes include impaired urinary water excretion and medication use, such as diuretics, antidepressants and antiepileptics.

 

Symptoms/Risks

• Weakness

• Dizziness

• Headache

• Nausea

• Vomiting

• Muscle cramps

• Confusion

• Seizures resulting in a coma

• Impaired coordination

• Difficulty breathing

 

Sports Medicine Evaluation and Treatment

When an athlete is suspected to have EAH, prompt evaluation by a physician is recommended. A sports medicine physician will be able to recognize signs and symptoms of EAH and rapidly initiate appropriate management. Lab tests will be needed to identify low serum sodium level and diagnose EAH.

Treatment of EAH is based on the severity of symptoms and can range from simple fluid restriction to oral or intravenous sodium replacement.

 

Injury Prevention

Avoid aggressive overhydration. Current recommendations, particularly for endurance athletes, novice athletes or athletes with inadequate training, suggest drinking according to individual thirst sensation, which is an internal signal the body generates and can be used as a real-time guide for fluid ingestion during exercise.

 

Return to Play

While there are no strict return-to-play guidelines, individualized plans should be made for closer sodium monitoring and appropriate fluid management strategies after appropriate treatment and complete resolution of symptoms.

AMSSM Member Authors
Edwin Hojilla, MD, and Laura McIntosh, MD, MBA

References
References:
Brukner P, Khan K. Clinical Sports Medicine. 4th ed. Australia: McGraw-Hill Education; 2012.
O’Connor FG, Casa DJ, Davis BA, St. Pierre P, Sallis RE, Wilder RP. ACSM’s Sports Medicine: A Comprehensive Review. Philadelphia: Wolters Kluwer Health; 2015.
Hew-Butler T, Rosner, MH, Fowkes-Godek, S, et al. Statement of the Third international exercise-associated hyponatremia consensus development conference, Carlsbad, CA, USA, 2015. Clin J Sport Med. 2015;25(4):303-320.
Bennett BL, Hew-Butler T, Rosner MH, Myers T, Lipman GS. Wilderness medical society clinical practice guidelines for the management of exercise-associated hyponatremia: 2019 update. J WEM. 2020;1(1):50-62.