Serum Biochemistry and Morbidity Among Runners Presenting for Medical Care After an Australian Mountain Ultramarathon

OBJECTIVE: To determine if exercise-associated hyponatremia (EAH) was a cause of morbidity among runners requiring medical care at an Australian mountain ultramarathon. DESIGN: Case series. SETTING: Six Foot Track mountain ultramarathon, New South Wales, Australia, March 2006. PATIENTS: Runners presenting to the medical facility. ASSESSMENT: Serum biochemistry. RESULTS: No cases of exercise-associated hyponatremia were identified among 9 athletes (from 775 starters) who were treated with intravenous fluid therapy. Unwell runners had a mean serum (Na) of 143 mmol/L (range 138-147 mmol/L). All runners tested had elevated serum urea and creatinine concentrations. CONCLUSION: In this setting, EAH was not a significant cause of morbidity.