12 September 2011
A study of hikers on the Kokoda Trail has confirmed the often overlooked and potentially fatal risk posed by excess water intake.
Researchers camped 2 days’ walk into – and 2 days from the end of – the track, where they took blood samples from 191 passing trekkers over 4 days.
Among 191 trekkers they identified 3 cases (1.6%) of hikers with mild exercise-associated hyponatraemia (EAH) – low salt levels in the blood - a condition viewed as a possible cause of recent unexplained deaths on the 96 kilometre track through the Papua New Guinean jungle.
"The study showed that EAH is prevalent on the Kokoda Trail," the authors wrote in the journal Emergency Medicine Australasia (2011, online 9 Sep).
"In view of the unexplained trail deaths and emergency retrievals, EAH might be an important medical condition affecting Kokoda Trail walkers."
"Strategies for education and prevention of EAH on the Kokoda Trail should be similar to those already established in competitive endurance events ... chiefly focusing on only drinking in response to thirst."
The 3 hikers with mild EAH had an estimated fluid intake on the day of testing almost double that of healthy hikers – at 6 litres versus 3.3 litres.
There have been 6 unexplained deaths on the trail since 2006 and emergency evacuations have become more common, the authors said.
There have also been 2 published cases of severe EAH in Kokoda trekkers, in 2006 and in 2008.
Despite this, knowledge of EAH remained "poor" among the hiking companies that operate on the track and "a 'just add water' approach" to hydration advice may still apply.
"Although it is vital to differentiate between dehydration and EAH," the symptoms of the 2 conditions are often similar, the authors also said.
"If EAH is erroneously diagnosed as dehydration and treated with fluid resuscitation [giving extra fluids], the consequences are potentially fatal."
The research was led by doctors from the department of emergency medicine at the Royal Brisbane and Women’s Hospital.
Last Reviewed: 12 September 2011