Background: Proper acute management of exercise-associated hyponatremia (EAH) has been known for decades, yet this information has not been uniformly implemented. Since treatment of EAH with isotonic fluids can result in delayed recovery and death, it is important that proper acute management in the field and hospital be utilized.
Case report: We describe a participant of the 161-km Western States Endurance Run (WSER) who presented with seizure after dropping out at 145 km. He had gained 2.2% of his initial weight by 126 km from using sodium supplements and drinking copious volumes of fluids. He was treated promptly in the field for presumed EAH with two intravenous boluses of 100 mL of 3% hypertonic saline and showed rapid improvement in neurologic status. His recovery was then delayed with the use of high volumes of intravenous isotonic fluids, apparently for concern over his mild exertional rhabdomyolysis.
Conclusions: Symptomatic EAH should be acutely managed with hypertonic saline, whereas treatment with high volumes of isotonic fluids may delay recovery and has even resulted in deaths from cerebral edema. Concern over central pontine myelinolysis from rapid correction of hyponatremia in EAH is unsupported. Furthermore, the exertional rhabdomyolysis often associated with EAH, and the concern over progression to acute kidney failure, should not dictate initial treatment.