Pre-adaptation, adaptation and de-adaptation to high altitude in humans: hormonal and biochemical changes at sea level

Abstract

High altitude residence is known to modify body biochemistry and hormone status. However, the effects of such a sojourn on these status observed at sea level both immediately and later after return are not as well established as are the effects of an intermittent acclimation. The aim of this study was therefore to investigate these changes. To achieve our objectives, nine subjects received intermittent acclimation at low pressure in a barometric chamber (8 h daily for 5 days, day 1 at 4500 m, day 5 at 8500 m) before an expedition to the Himalayas. Hormonal and biochemical changes were studied using samples of venous blood taken at sea level before and after acclimation, after return from the expedition and 1 and 2 months after descent. Concentrations of thyroid hormones, adrenaline, noradrenaline (NA), hormones of hydromineral metabolism (aldosterone, renin, arginine vasopressin, atrial natriuretic peptide) as well as prolactin, cortisol, insulin and endothelin 1 were measured. Biochemical measurements made were plasma osmolality, and concentrations of glucose, total cholesterol, total proteins, pre-albumin, transferrin, complement 3C, apolipoproteins A1 and B and serum iron. Acclimation induced no alteration in hormone (except for NA with increases of about 1.5, fold P < 0.05) and biochemistry data. After the expedition, hormone responses were characterized by a higher total triidothyronine concentration (+18%, P < 0.05) while other hormones did not vary. A linear relationship was found between thyroid-stimulating-hormone and body mass changes after the expedition (r = 0.67, P < 0.05). The observed increased concentrations of plasma proteins and total cholesterol (P < 0.05) could be related to the restoration of lean body mass. At 1 and 2 months after return, no changes in hormones were observed but a significant decrease in transferrin concentration was noticed. The higher serum iron concentration reported after 1 month (P < 0.05) could have been the result of a physiological haemolysis. It was concluded that both acclimation and the expedition in the Himalayas affected hormone status and body biochemistry status even though the observed changes were slight and rapidly reversed.

Moderately high altitude habitation modulates lipid profile and alkaline phosphatase activity in aged Khasis of Meghalaya

“…The effects of exposure to high altitude on lipid metabolism appear to be complex, interrelated processes involving multiple responses by the human body. The report of elevation of serum total cholesterol and LDL-cholesterol in people from high altitude areas by few investigators (18)(19)(20) is however not supported by our finding, wherein we report a decreased total cholesterol and LDL-cholesterol levels in O S subjects. Our finding is also in contrast to another report where there is a significantly higher serum triglyceride level in subjects who are inhabitants of moderately high altitude (21).…”

Control of erythropoiesis after high altitude acclimatization

“…This sojourn induced also a body-mass loss (P<0.01) essentially from body-fat content (P<0.01); the observed decrease in lean body mass (À0.36 kg) was not significant. Body-mass loss at altitude is a classic feature reported in the literature (Kayser 1992;Richalet et al 1994;Ward et al 1995;Savourey et al 1998) and is a function of the duration of stay and the altitude (Kayser 1992).…”

Effect of repeated normobaric hypoxia exposures during sleep on acute mountain sickness, exercise performance, and sleep during exposure to terrestrial altitude

“…Previous studies reporting a direct relationship between higher Sa O 2 levels and either reduced AMS (1, 3) or blood EPO levels (13,19) or between lower Sa O 2 levels and increased AMS (9) are consistent with our interpretation. Whether our findings of apparent sleep response specificity may be related to possible physiological differences or signaling mechanisms in response to NH and HH treatments (10,25) that may be of benefit for the planning of future acclimatization strategies cannot be determined from the results of this study.…”