Endocrine Aspects of High Altitude Acclimatization and Acute Mountain Sickness

Abstract

The acute acclimatization to high altitude is underpinned by a diuresis (and to a lesser extent a natriuresis) that facilitates a reduction in plasma volume. This allows a haemoconcentration to occur that increases the oxygen carrying capacity of a given volume of blood, a vital effect in the presence of a reduced partial pressure of oxygen. This critical acclimatization process is orchestrated by the endocrine system. This review will present the key evidence regarding the changes in several important hormones that affect this process.

Hypoxic training: Clinical benefits on cardiometabolic risk factors

“…It was reported that during acute exposure to high altitude, fluid loss could be as much as 3L [31]. Hence, to determine the effectiveness of hypoxic training, future studies should attempt to minimise fluid loss and ensure the participants are euhydrated.…”

Exploring the Mediators that Promote Carotid Body Dysfunction in Type 2 Diabetes and Obesity Related Syndromes

“…These adaptations in glucose homeostasis mechanisms seem to be reflected in the inverse association found between the prevalence of diabetes and obesity with altitude in the United States adult population [130]. The initial, transient hyperglycemia could be partially attributed to the increase in sympathetic nervous system activity [130] and stress hormones, mainly catecholamines that have been documented to increase with altitude [131,132] and that are in agreement with a possible overactivation of the CB.…”

“…Ibuprofen and dexamethasone, two anti-inflammatory drugs, administered for 8-10 days of CSH decreased the rise in CB IL-1β, IL-6, and TNF-α expression induced by CSH and abolished the increase in CSN frequency of discharge induced by hypoxia in these animals [132], suggesting that the effect of CSH on chemoreceptor excitability is mediated by a local immune response in the CB. Additionally, ibuprofen treatment in rats blocked the increase in HVR described in rats exposed to CSH for 7 days at 70 Torr [135].…”

Geographical Determinants of the Prevalence of Gestational Diabetes in North and South Kivu in the Democratic Republic of Congo

“…A cortisol level of ˃275 nmol/L was associated in this study with a higher prevalence of gestational diabetes. As this study involved pregnant women who had been living in the sites for at least 30 days, their metabolism would therefore no longer be due to changes in altitude as demonstrated by certain results whose authors had respectively found that the endocrine response to altitude normalized in the five days following the climb, in particular the cortisol level and that the variations in the cortisol level stabilized after a stay of 30 days or more at high altitude [21,22]. Interested in adapting to stress had noted that the average cortisol level was higher in pregnant women with gestational diabetes: 502.75 ± 124 nmol/L Vs 464.62 ± 110 nmol/L in the absence of gestational diabetes [23].…”