Electrolyte regulation during the adaptation of humans to life at high altitude

Abstract

Studies related to the body’s regulation of its sodium and potassium content have been made on a number of occasions during periods spent at high altitude. It is shown that on ascent from usual levels of residence the ratio of sodium to potassium in the saliva tends to rise above normal and later to fall with continued residence at altitude. The implications of this finding have been confirmed by subsidiary studies. The urinary aldosterone excreted while resident at altitude has been assayed and it has been shown to fall to very low levels. In contrast to what occurs with 17-hydroxycorticosteroids there appears to be a delay in the fall of urinary aldosterone although this has still to be confirmed by further studies which are in course of preparation. With continued residence at high altitude the urinary aldosterone level recovers but complete recovery takes several weeks. Published data are reviewed and it is concluded that these results are due to the changes in intravascular volume which occur on ascent to an environment of reduced p⁰₂. It is probable that the significant volume changes are intrathoracic.