title: Adaptation of ghrelin and the GH/IGF axis to high altitude.
abstract: OBJECTIVE
  High altitude (HA) provokes a variety of endocrine adaptive processes. We investigated the impact of HA on ghrelin levels and the GH/IGF axis.
  
  
  METHODS
  Observational study as part of a medical multidisciplinary project in a mountainous environment.
  
  
  METHODS
  Thirty-three probands (12 females) were investigated at three timepoints during ascent to HA (A: d -42, 120 m; B: d +4, 3440 m; C: d +14, 5050 m). The following parameters were obtained: ghrelin; GH; GH-binding protein (GHBP); IGF1; IGF2; IGF-binding proteins (IGFBPs) -1, -2, and -3; acid-labile subunit (ALS); and insulin. Weight was monitored and general well being assessed using the Lake Louise acute mountain sickness (AMS) score.
  
  
  RESULTS
  Ghrelin (150 VS 111PG/ML; P0.01) and GH (3.4 VS 1.7G/L; P0.01) were significantly higher at timepoint C compared with A whereas GHBP, IGF1, IGF2, IGFBP3, ALS, and insulin levels did not change. IGFBP1 (58 VS 47G/L; P0.05) and, even more pronounced, IGFBP2 (1141 VS 615G/L; P0.001) increased significantly. No correlation, neither sex-specific nor in the total group, between individual weight loss (females: -2.1 kg; males: -5.1 kg) and rise in ghrelin was found. Five of the subjects did not reach investigation point C due to AMS.
  
  
  CONCLUSIONS
  After 14 days of exposure to HA, we observed a significant ghrelin and GH increase without changes in GHBP, IGF1, IGF2, IGFBP3, ALS, and insulin. Higher GH seems to be needed for acute metabolic effects rather than IGF/IGFBP3 generation. Increased IGFBP1 and -2 may reflect effects from HA on IGF bioavailability.
authors.affiliation: Pediatric Department, St Anna Children's Hospital, Medical University of Vienna, Kinderspitalgasse 6, Vienna, Austria. stefan.riedl@meduniwien.ac.at
authors.forename: Stefan
authors.initials: S
authors.lastname: Riedl
authors.forename: Michael
authors.initials: M
authors.lastname: Kluge
authors.forename: Katharina
authors.initials: K
authors.lastname: Schweitzer
authors.forename: Thomas
authors.initials: T
authors.lastname: Waldhör
authors.forename: Herwig
authors.initials: H
authors.lastname: Frisch
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness; D001835:Body Weight; D002352:Carrier Proteins / Q000097:blood*; D005260:Female; D054439:Ghrelin / Q000097:blood*; D006023:Glycoproteins / Q000097:blood*; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D007328:Insulin / Q000097:blood*; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000097:blood; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D013002:Somatomedins / Q000378:metabolism*; D013997:Time Factors; D044465:White People
chemical_list: D002352:Carrier Proteins; D054439:Ghrelin; D006023:Glycoproteins; D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins; C075944:insulin-like growth factor binding protein, acid labile subunit; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; C051815:somatotropin-binding protein