Elevated PBI, free thyroxine, and plasma protein concentration in man at high altitude.

Publisher Website
Google Scholar
Abstract
Various aspects of thyroxine binding by plasma proteins have been studied in 8 sea-level residents before, during, and after 28 days exposure to 14,100 ft. altitude. Mean plasma concentration of protein-bound iodine and total protein and the binding capacity of thyroxine-binding globulin were elevated within 3 days, reached a maximum after 9 days, and returned toward low-altitude values between 12-15 days at altitude. They reached control levels within 4 days after descending to sea level. In spite of an increased intensity of thyroxine binding by plasma proteins, the concentration of plasma free thyroxine was increased at altitude. Since the electro-phoretic distribution of plasma proteins was unaltered, plasma dehydration in the initial phase of altitude exposure was concluded to be responsible for most of the observed alterations in thyroxine binding. A decrease in mean binding capacity of thyroxine-binding prealbumin is interpreted to reflect changes in protein synthesis and/or degradation which may also occur in this environment.