Heat Exhaustion or Hyponatremia?
Participants in marathons and other endurance events across the nation have become confused and collapsed during competitions due to hyponatremia. However, many more participants in these very events have become confused and collapsed from dehydration, heat exhaustion, or heat stroke.The need to remain hydrated during periods of exertion, particularly in hot climates, makes it difficult to recognize hyponatremia symptoms. Severe dehydration and heat exhaustion look very similar to hyponatremia and, like hyponatremia, are more common in hot weather during exercise.
Hyponatremia Symptoms
Hyponatremia symptoms include:- weakness
- dizziness
- nausea
- muscle cramps
- slurred speech
- confusion
- loss of consciousness
- seizures in severe cases
Hyponatremia First Aid
Victims with slurred speech, confusion, severe weakness, or loss of consciousness need medical attention immediately. Call 911 for these victims, regardless of the cause.Heat exhaustion and dehydration can look very much like hyponatremia and are much more common. Heat stroke has a distinct set of symptoms and is a serious emergency.
Determine if the victim has been staying hydrated. If witnesses can confirm the victim has been drinking at least a pint of fluid per hour during exercise, consider the possibility of hyponatremia. In cases of rapid massive water intake -- such as college fraternity initiation -- consider the possibility of hyponatremia.
Victims of hyponatremia need salt. In minor cases -- usually just when nausea is present -- before cramps, dizziness or confusion occur, victims may feel better with salty food intake. Be very careful not to treat dehydration as hyponatremia and suggest salty foods when the victim really needs fluid. Assume any victim complaining of thirst is dehydrated.
Avoid NSAIDs like ibuprofen, aspirin, or naprosyn when concerned about hyponatremia. These pain relievers may make symptoms worse.
Sources:
Almond, Christopher S.D., et al. "Hyponatremia among Runners in the Boston Marathon." New England Journal of Medicine. 14 APR 2005.
Vrijens, D. M. J., and N. J. Rehrer. "Sodium-free fluid ingestion decreases plasma sodium during exercise in the heat." J Appl Physiol. Vol. 86, Issue 6, 1847-1851, June 1999.
