title: Changes in insulin-like growth factor-I and -II associated with fat but not lean mass in early old age.
abstract: OBJECTIVE
  To test the hypothesis that insulin-like growth factors-I and II (IGF-I and II) decline during late midlife and that greater declines are related to higher fat mass and lower lean mass.
  
  
  METHODS
  A total of 1,542 men and women in a British birth cohort study had IGF-I and II measured by immunoassay of blood samples at age 53 and/or 60-64 years. Fat mass, android:gynoid fat ratio, and appendicular lean mass were measured at 60-64 years using dual-energy X-ray absorptiometry (DXA). Associations between changes in IGF-I or II and body composition outcomes were examined using conditional change linear regression models.
  
  
  RESULTS
  Mean IGF-I and IGF-II concentrations were lower at 60-64 than at 53 years, by 12.8% for IGF-I and by 12.5% for IGF-II. Larger declines in either IGF-I or II were associated with higher fat mass at 60-64 years. Although higher IGF-I at 53 years was associated with higher lean mass, there was little evidence linking changes in IGF-I or II to lean mass.
  
  
  CONCLUSIONS
  The findings suggest that IGF-I and II concentrations decline with age, and greater declines are associated with higher fat mass levels. These results provide some evidence for the suggested roles of IGF-I and II in regulating fat mass but not lean mass in older age.
authors: MRC Unit for Lifelong Health and Ageing, University College London, London, UK.
authors: David
authors: D
authors: Bann
authors: Jeff M P
authors: JM
authors: Holly
authors: Hany
authors: H
authors: Lashen
authors: Rebecca
authors: R
authors: Hardy
authors: Judith
authors: J
authors: Adams
authors: Diana
authors: D
authors: Kuh
authors: Ken K
authors: KK
authors: Ong
authors: Yoav
authors: Y
authors: Ben-Shlomo
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000033:anatomy & histology* / Q000378:metabolism; D000375:Aging / Q000097:blood / Q000378:metabolism*; D001823:Body Composition / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000378:metabolism
chemical_list: D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II
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