title: The cortisol response to hypobaric hypoxia at rest and post-exercise.
abstract: High altitude exposure normally leads to a marked natriuresis and diuresis. Acute mountain sickness is often associated with fluid retention, to which an elevated cortisol may contribute. Most investigators report a rise in resting cortisol with ascent, but little data exist regarding the cortisol response to a day trekking. We therefore measured salivary cortisol during ascent to > 5000 m in a cohort of between 42-45 subjects following a 6-h trek (samples taken between 15:30-16:30 h) and between 15-20 subjects at rest (morning samples taken between 08:00-09:00 h). Morning resting cortisol [nmol/l, mean±sd, (range)] was 5.5±2.9 (2.13-13.61) at 1300 m; 4.7±6.8 (1.4-27.02) at 3400 m, and significantly (p=0.002) rose between 4270 m [3.5±2.1 (1.4-8.34)] and 5150 m [14.5±30.3 (1.9-123.1)]. Post-exercise cortisol [nmol/l, mean±sd, (range)] dropped between 3400 m [7±6 (1.5-33.3)] and 4270 m [4.2±4.8 (1.4-29.5)] (p=0.001) followed by a significant rise in post-exercise cortisol between 4270 m [4.2±4.8 (1.4-29.5)] and 5 150 m [9.2±10.2 (1.4-61.3)] (p<0.001). There were no significant associations between severity of acute mountain sickness and cortisol levels. There was a significant though weak correlation between cortisol post-exercise at 5150 m and oxygen saturation at 5150 m (rho= - 0.451, p=0.004). In conclusion, this is the largest cohort to have their resting and post-exercise cortisol levels ascertained at high altitude. We confirm the previous findings of an elevated resting morning cortisol at > 5000 m, but present the novel finding that the cortisol response to a day trekking at HA appears suppressed at 4270 m.
authors.affiliation: Northumbria and Newcastle NHS Trusts, Royal Victoria Infirmary and Wansbeck General, Newcastle upon Tyne, UK. DoctorDRWoods@aol.com
authors.forename: D R
authors.initials: DR
authors.lastname: Woods
authors.forename: A
authors.initials: A
authors.lastname: Davison
authors.forename: M
authors.initials: M
authors.lastname: Stacey
authors.forename: C
authors.initials: C
authors.lastname: Smith
authors.forename: T
authors.initials: T
authors.lastname: Hooper
authors.forename: D
authors.initials: D
authors.lastname: Neely
authors.forename: S
authors.initials: S
authors.lastname: Turner
authors.forename: R
authors.initials: R
authors.lastname: Peaston
authors.forename: A
authors.initials: A
authors.lastname: Mellor
mesh_terms: D000328:Adult; D000532:Altitude Sickness / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012146:Rest / Q000502:physiology*; D012463:Saliva / Q000737:chemistry / Q000378:metabolism; D055815:Young Adult
chemical_list: D006854:Hydrocortisone