Mr. Salty to the Rescue

Don't let sodium deficiency trip you up on the trail

Apr 1, 2000
Outside Magazine

"I'm on a new campaign to push junk food on the trail," announces Sherrie Collins, branch chief of emergency services for Grand Canyon National Park. "My favorite is Cheez-Its." Collins's preoccupation with the unnaturally orange snack food stems from the fact that a single-serving bag contains 40 milligrams of sodium—enough to stave off hyponatremia, a condition involving critically low levels of sodium in the blood that plagues increasing numbers of mountaineers, adventure racers, and day hikers.

During periods of sustained physical exertion, your body prevents itself from overheating by flushing water through the pores of your skin. The price for keeping cool is that you not only lose enormous amounts of water—up to 25 milliliters each minute—but also significant amounts of salt (hence those unsightly white rings around your armpits after an epic mountain bike ride). The traditional mantra for outdoor enthusiasts—drink water or die—helps you to redress the H2O deficit, but it does nothing to replace the lost salt, which is critical for transmitting nerve impulses in the brain. Once blood-sodium concentration drops below 9 percent, hyponatremia sets in. The symptoms, which include malaise, confusion, and nausea, can presage severe and in some instances fatal complications.In 1998, Kelly Barret, a 43-year-old distance runner, died while participating in the Chicago Marathon. Although his death was attributed to a rare heart condition, doctors said it was aggravated by hyponatremia. Part of the problem is that in its early stages, hyponatremia mimics heat exhaustion, which makes diagnosis quite difficult. "They look exactly alike," says Collins, "but you treat them differently."

During the last few years, efforts to detect, treat, and prevent hyponatremia have increased significantly. In 1997, Dale Speedy, a University of Auckland physician, conducted the first comprehensive hyponatremia study at the New Zealand Ironman and found the condition in one-fifth of 330 finishers. Those numbers have gone down in the past two years, but cases in noncompetitive outdoor activities have rocketed upward. In 1989, the first hyponatremic hiker was evacuated from the Grand Canyon; by 1999, the number of diagnoses in the park had risen to 36. The elevating statistics led park rangers to pioneer the use of portable blood-chemistry analyzers in 1996, which allow for on-the-spot assessment and treatment. This summer, Collins is trying to add another of those $5,000 analyzers to the three currently in use. She's also expanding the park's Web site to educate visitors about the risks of hyponatremia during desert hiking.

Experts say that prevention hinges on maintaining a consistent water-sodium balance by not drinking too much water and by replenishing at least some of that lost salt. Caveat: Don't overdue it. The simplest remedy is an off-the-shelf sports drink like Gatorade, which is loaded with sodium-rich electrolytes. Or, as Collins points out, Cheez-Its—a prescription that may soon imbue the snack food with a noble new role. "Now," notes Hawaii Ironman medical director Bob Laird, "it can save lives."


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