title: Association of insulin-like growth factor-I with body composition, weight history, and past health behaviors in the very old: the Framingham Heart Study.
abstract: OBJECTIVE
  We examined correlates of insulin-like growth factor-I (IGF-I), an indicator of growth hormone levels, to identify factors associated with higher levels of IGF-I in old age.
  
  
  METHODS
  Nested study of cross-sectional correlates and early-life predictors of IGF-I level.
  
  
  METHODS
  A longitudinal cohort study, the Framingham Heart Study.
  
  
  METHODS
  A total of 790 men and women (mean age 78.5, range 72-94), who had weight, waist and hip circumferences measured at the time of IGF-I measurement.
  
  
  METHODS
  Association of IGF-I with weight, fat distribution, functional status, nutritional indicators, and past health behaviors was assessed. We also examined IGF-I in relation to body composition derived from dual energy X-ray absorptiometry.
  
  
  RESULTS
  IGF-I levels declined with age in both men and women. However, low IGF-I did not show expected associations with low lean mass and increased body fat. Current functional status and grip strength were not associated with IGF-I Low IGF-I was associated with weight loss in men; the strongest associations were with indicators of poorer nutritional status in both men and women. Levels of IGF-I in old age did not vary by past health behaviors.
  
  
  CONCLUSIONS
  Although IGF-I declined with age, these data from the Framingham Heart Study did not show expected cross-sectional associations of weight, body fat, and lean mass. The strongest associations were between IGF-I and nutritional indicators. These results suggest caution may be warranted with regard to use of IGF-I as an indicator of growth hormone.
authors.affiliation: National Institute on Aging, Epidemiology, Demography and Biometry Program, Bethesda, MD 20892-9205, USA.
authors.forename: T B
authors.initials: TB
authors.lastname: Harris
authors.forename: D
authors.initials: D
authors.lastname: Kiel
authors.forename: R
authors.initials: R
authors.lastname: Roubenoff
authors.forename: J
authors.initials: J
authors.lastname: Langlois
authors.forename: M
authors.initials: M
authors.lastname: Hannan
authors.forename: R
authors.initials: R
authors.lastname: Havlik
authors.forename: P
authors.initials: P
authors.lastname: Wilson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over / Q000502:physiology / Q000523:psychology; D001823:Body Composition; D001835:Body Weight; D005260:Female; D013006:Growth Hormone / Q000378:metabolism; D015438:Health Behavior; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism* / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D008404:Massachusetts; D009752:Nutritional Status
chemical_list: D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone