Sodium, Potassium, and Chloride Excretion of Human Subjects Exposed to a Simulated Altitude of Eighteen Thousand Feet*

The major electrolyte change for a man working and living at 5.34 to 5.80 km. was shown by Dill and coworkers (1) to be a decrease in bicarbonate and sodium content of the serum and some increase in its chloride content. It was demonstrated by Davies, Haldane, and Kennaway (2) and by Leathes (3) that forced breathing of air resulted in a diuresis of an alkaline urine. It was also shown (2) that the increased alkalinity of the urine was largely due to bicarbonates. It is possible that a reduced oxygen tension in the atmosphere may directly or indirectly influence the excretion of sodium and potassium in the urine; yet there is surprisingly little information on this subject in the literature. The possibility that the requirements for these elements might be altered in aviators or others maintained at high altitudes led to the study of this question in human subjects under conditions of simulated high altitude.