title: Brain natriuretic peptide at altitude: relationship to diuresis, natriuresis, and mountain sickness.
abstract: BACKGROUND
  Acute mountain sickness (AMS) affects some new arrivals above an altitude of 2500 m. Hypobaric hypoxia is known to produce diuresis and has natriuretic effects due to the release of natriuretic peptides. We tested the hypothesis that increases in brain natriuretic peptide (BNP) at altitude correlates with increased urination and natriuresis as well as symptomatic AMS.
  
  
  METHODS
  Subjects were 14 mountaineers who undertook a Himalayan expedition that began at 100 m and passed through 3440 m en route to a final altitude of 5050 m. We measured the severity of AMS (Lake Louise Score), BNP values, nocturnal urine volume, and urine sodium concentration.
  
  
  RESULTS
  Nocturnal urine volume increased from 490 +/- 90 mi at 3440 m to 1100 +/- 104 ml at 5050 m. BNP levels at the higher altitude were 10.6 +/- 4.7 pg x ml(-1) and were correlated with the severity of AMS in all mountaineers (Lake Louise Score 4 +/- 0.5 for AMS subjects). However, AMS severity did not correlate with urine volume or urine sodium concentration.
  
  
  CONCLUSIONS
  Our results suggest that BNP secretion is not the cause of high-altitude diuresis. Further studies are needed to evaluate the possible role of BNP in individual responses to high altitude.
authors.affiliation: University of Munich, Klinikum Grosshadern, Department of Neurology, Marchioninistr. 15, D-81377 Munich, Germany. berend.feddersen@med.uni-muenchen.de
authors.forename: Berend
authors.initials: B
authors.lastname: Feddersen
authors.forename: Harald
authors.initials: H
authors.lastname: Ausserer
authors.forename: Bernd
authors.initials: B
authors.lastname: Haditsch
authors.forename: Herwig
authors.initials: H
authors.lastname: Frisch
authors.forename: Soheyl
authors.initials: S
authors.lastname: Noachtar
authors.forename: Andreas
authors.initials: A
authors.lastname: Straube
mesh_terms: D000328:Adult; D000368:Aged; D000531:Altitude; D000532:Altitude Sickness / Q000097:blood* / Q000503:physiopathology; D004231:Diuresis / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009318:Natriuresis / Q000502:physiology*; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D014556:Urine; D055815:Young Adult
chemical_list: D020097:Natriuretic Peptide, Brain