Medicine for the Outdoors
Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Hydration Question

A reader writes: “I have been told that under most circumstances a properly hydrated person should be urinating every 1 and 1/2 to 2 hours. Is this accurate?”

This is probably a reasonable statement, although there is no absolute correlation of time interval between episodes of spontaneous (e.g., associated with the urge to urinate) urination and state of hydration. For instance, a person might be well hydrated and exercising, so not appreciate an urge to urinate. Exercise is also the reason why a person may not appreciate thirst, so until someone takes a break from the exercise and attempts to urinate, it may be difficult to tell exactly where someone is from a hydration perspective.

The general rule is to drink enough liquid so that the urine is light-colored and copious, no matter what the interval between episodes of urination. If the urine is dark-colored, this may indicate that it is concentrated (with waste products), which occurs when the kidneys (and body) are working to conserve fluid. “Cloudy” (not clear) urine may be caused by excess protein in the urine, a urinary tract infection, or some other reason. Using the urine hydration chart depicted above, urine should not be darker in color than #4.

It’s easy to become dehydrated outdoors, as most people underestimate their fluid requirements. Situations of particularly high risk include cold, dry weather (respiratory fluid loss from breathing, particularly if it is rapid), high altitude (loss of thirst and breathing cold, dry air), extreme heat (nausea, inadequate thirst), during times of great exertion, and with any intercurrent illness (particularly if it involves nausea and vomiting). These are times when it is important to drink a minimum of two liters (quarts) of water when there is no significant fluid loss (e.g., at rest in a non-stressful environment), and more if conditions warrant. So long as alcohol is not ingested and one avoids any beverage with a diuretic effect, it doesn’t make much difference what beverage is chosen. Drink what you like, and drink enough.

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

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About the Author

Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.