Exercise-associated hyponatraemia on the Kokoda Trail

Objective: The objective of the present study was to determine the prevalence of exercise-associated hyponatraemia in hikers/trekkers along the Kokoda Trail. Methods: This was a cross-sectional study of 191 trekkers on the Kokoda Trail, Papua New Guinea. Blood was taken and analysed immediately using point-of-care technology 2 days walk from each end of the Trail. Results: The main outcome measure was hyponatraemia defined as serum sodium level less than 135 mmol/L. Three participants (1.6%, 95% CI 0.5–4.5%) were found to have mild hyponatraemia. The hyponatraemic group had a median estimated fluid intake on the day of testing that was almost double that of the normal sodium group (6 L vs 3.3 L). Conclusion: Exercise-associated hyponatraemia occurs in trekkers on the Kokoda Trail. Strategies for prevention of exercise-associated hyponatraemia should be delivered to trekkers via the trekking companies, chiefly focussing on only drinking in response to thirst.