ABSTRACT
For many decades, scientific opinion and alpine folklore have claimed that those who acclimatized to high altitude had increased urination (Ho¨hendiurese), whereas those who fared poorly exhibited oliguria and edema, suggesting a critical role of the kidneys and fluid balance in transition to an hypoxic environment. Yet even 70 years since the first reports on fluid balance at high altitude, the effects of hypoxia on salt and water homeostasis remain poorly elucidated. Hypoxia can directly affect the kidneys, but, more importantly, its effects on systemic acid-base status, ventilation, neuroendocrine reflexes, and hemodynamics all play a far greater part in altering renal function and fluid balance. Other features of high altitude separate from hypoxia, either alone or in combination, including hypobaria, exercise, and cold, may also significantly perturb renal function.
