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.