Impaired osmoregulation at high altitude. Studies on Mt Everest
F. D. Blume, S. J. Boyer, L. E. Braverman, A. Cohen, J. Dirkse and J. P. Mordes
Osmoregulation was studied in 13 mountaineers who had experienced long-term
exposure to high altitude on Mt Everest. Serum osmolality rose from 290 +/-
1 mOsm/kg to 295 +/- 2 mOsm/kg at 5,400 m and finally to 302 +/- 4 mOsm/kg
at 6,300 m after a mean of 26.5 days above 5,400 m. Despite this degree of
osmoconcentration, plasma arginine-vasopressin concentration remained
unchanged: 1.1 +/-0.1 microU/mL at sea level, 0.8 +/- 0.1 microU/mL at
5,400 m, and 0.9 +/- 0.1 microU/mL at 6,300 m. Urinary vasopressin
excretion was also similar at all three altitudes. We conclude that
prolonged exposure to high altitude may result in persistent impairment of
osmoregulation, caused in part by an inappropriate arginine-vasopressin
response to hyperosmolality.
