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.