title: Urinary leukotriene E4 levels increase upon exposure to hypobaric hypoxia.
abstract: OBJECTIVE
  To determine whether urinary leukotriene E4 (uLTE4) levels increase upon exposure to high altitude, and also to ascertain the relationship between uLTE4 levels and symptoms of acute mountain sickness (AMS).
  
  
  METHODS
  Prospective, unblinded, single-factor (altitude) experimental study.
  
  
  METHODS
  US Army research laboratory facilities at sea level ([SL] 50 m), 1,830 m, and 4,300 m.
  
  
  METHODS
  Eight healthy male subjects ranging in age from 19 to 24 years.
  
  
  METHODS
  uLTE4 levels and symptoms of AMS were measured at just above SL (50 m), 3 1/2 days after being transported from SL to moderate altitude (MA) (1,830 m), and 1 1/2 days after ascent from 1,830 to 4,300 m (high altitude [HA]). Symptoms of AMS were assessed using standard indexes derived from the Environmental Symptoms Questionnaire weighted toward cerebral (AMS-C) and respiratory (AMS-R) manifestations. Oxygen saturation was measured noninvasively by pulse oximetry at SL and HA.
  
  
  RESULTS
  The mean (+/-SEM) uLTE4 levels (pg/mg creatinine) were 67.9 (+/-13.2) at SL; 82.3 (+/-5.5) at MA; and 134.8 (+/-19.4) at HA (p < 0.05 comparing HA with SL and MA).
  
  
  CONCLUSIONS
  We conclude that uLTE4 levels increase shortly after exposure to HA even after staging for 4 days at MA. Although this study does not clearly demonstrate a relationship between uLTE4 levels and symptoms of AMS, it supports the hypothesis that leukotrienes may be involved in the pathophysiologic state of AMS.
authors.affiliation: Altitude Physiology and Medicine Division, US Army Research Institute of Environmental Medicine Natick, Mass, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Roach
authors.forename: S R
authors.initials: SR
authors.lastname: Muza
authors.forename: P B
authors.initials: PB
authors.lastname: Rock
authors.forename: T P
authors.initials: TP
authors.lastname: Lyons
authors.forename: C M
authors.initials: CM
authors.lastname: Lilly
authors.forename: J M
authors.initials: JM
authors.lastname: Drazen
authors.forename: A
authors.initials: A
authors.lastname: Cymerman
mesh_terms: D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000503:physiopathology / Q000652:urine*; D006801:Humans; D000860:Hypoxia / Q000652:urine*; D017999:Leukotriene E4 / Q000502:physiology / Q000652:urine*; D008297:Male; D011446:Prospective Studies
chemical_list: D017999:Leukotriene E4