High-Altitude Pituitary–Thyroid Dysfunction on Mount Everest

Abstract

THE process of adaptation to high altitude has been studied extensively.1 Most studies, however, have been performed at altitudes under 5000 m (16,400 ft). This altitude is of interest because it appears to define the highest altitude at which human beings can reside indefinitely. Although some 25 million people2 live at between 3000 and 5000 m, there are few permanent settlements at higher altitudes. We now report observations on pituitary and thyroid function at sea level and at 5400 m (17,700 ft) and 6300 m (20,700 ft). There was a progressive rise in serum thyroxine (T4) concentrations and . . .