[Altitude hypoxia: effects on selected endocrinological parameters].

During the past few years, the investigation of altitude hypoxia and its effect on metabolic functions in humans has increasingly attracted the attention of endocrinologists. Most of the studies have been performed as field studies at moderate or high altitude, but with conflicting results. One of the possible reasons certainly is the fact that standardisation of field studies is almost impossible. Furthermore, many factors such as wind, temperature, radiation and others, may affect certain endocrine parameters, but they cannot be individually quantified. Hence, their inclusion into statistical analyses of the obtained data is not useful. Nevertheless, several endocrine parameters were shown to be affected by altitude hypoxia. Among them, there is erythropoietin, a hormone which is well known to stimulate erythropoiesis. This hormone shows a rapid increase after ascent to moderate or high altitude. There is also evidence that urinary and serum noradrenalin levels increase significantly, whereas adrenalin seems to be less affected. Another "stress-hormone", cortisol, also shows a significant increase. Furthermore, the biologically active fraction of the thyroidal hormones thyroxine and triiodothyronine increases significantly. And last but not least, one of the most important proinflammatory cytokines, interleukin-6, shows a manyfold increase compared to the basal level. However, the clinical significance of most of these studies is not yet clear. Hence, from an endocrinological point of view, no specific recommendations may be given to people staying at moderate or high altitude.