Low- and High-Altitude Cortisol Awakening Responses Differ Between AMS-Prone and AMS-Resistant Mountaineers.

Abstract

Estoppey, Jan, Bertrand Léger, Philippe Vuistiner, Claudio Sartori, and Bengt Kayser. Low and high altitude cortisol awakening responses differ between AMS-prone and AMS-resistant mountaineers. High Alt Med Biol 00:000-000, 2019. Background: Mechanisms underlying acute mountain sickness (AMS) remain unclear. Corticosteroids are effective for prevention and treatment suggesting a role for deficient endogenous cortisol. The cortisol awakening response (CAR), the increase in cortisol secretion over the first 30-45 minutes after morning awakening, better reflects the hypothalamic-pituitary-adrenal (HPA) axis than single cortisol measurements. We hypothesized that CAR may be altered in AMS-prone persons. Methods: Upon arrival at 4554\u2009m (high altitude [HA]), 81 mountaineers agreed to participate. The following morning, they gave three saliva samples after awakening (S1: 0 minute, S2: 30 minutes, S3: 45 minutes). AMS was scored with the 1993 Lake Louise Score (LLS, cut-off ≥5). Minimally 4 weeks after descent, saliva was recollected by 58 of 81 participants at low altitude (LA); 382\u2009±\u2009309\u2009m, mean\u2009±\u2009standard deviation). Cortisol was quantified by immunoassay. Three cortisol indices were analyzed: first sample on awakening (S1), CAR (area under curve with respect to S1) and total post awaking cortisol (area under the curve from ground [AUC-G]). Results: AMS prevalence was 30%. At HA compared to LA, S1 (450\u2009±\u2009190 vs. 288\u2009±\u2009159\u2009ng/dL, p\u2009<\u20090.001) and AUC-G (387\u2009±\u2009137 vs. 276\u2009±\u2009114\u2009ng/dL·min, p\u2009<\u20090.001) were greater, but CAR was not (50\u2009±\u2009100 vs. 60\u2009±\u200981\u2009ng/dL·min, p\u2009=\u20090.550). AMS+ compared to AMS- participants had higher S1 both at HA (495\u2009±\u2009209 vs. 384\u2009±\u2009176\u2009ng/dL, p\u2009=\u20090.016) and LA (354\u2009±\u2009160 vs. 253\u2009±\u2009142\u2009ng/dL, p\u2009=\u20090.015) and lower CAR at LA (24\u2009±\u200987 vs. 79\u2009±\u200972\u2009ng/dL·min, p\u2009=\u20090.013). AUC-G was similar in both groups at HA and LA. Conclusions: Some indices of salivary cortisol response upon awakening differ between AMS+ and AMS-, both at HA and LA, suggesting a link between HPA-axis homeostasis and AMS.