title: Serum insulin-like growth factor-I and body composition in community dwelling older people.
abstract: OBJECTIVE
  The decline in the growth hormone/insulin-like growth factor-I (GH/IGF-I) axis during normal aging might be involved in the changes in body composition associated with increasing age. We conducted a study to investigate serum IGF-I levels across different age categories and a possible association between serum IGF-I and measurements of body composition in older people.
  
  
  METHODS
  A cross-sectional analysis of community dwelling older people, which participated in a large longitudinal cohort study (Longitudinal Aging Study Amsterdam).
  
  
  METHODS
  1319 subjects, 644 men, mean age 75.6 +/- 6.6 years and 675 women, mean age 75.4 +/- 6.6 years.
  
  
  METHODS
  IGF-I, body mass index (BMI), waist, waist-hip ratio (WHR), fat mass, lean body mass and total bone mineral density.
  
  
  RESULTS
  IGF-I levels were significantly lower in the highest age categories. BMI and biceps skinfold measurements were lower in the lowest IGF-I quartile in men aged > or =75.5 years. In men with a low total physical activity score (<131 min/day), BMI, WHR and skinfolds were significantly lower in the lowest IGF-I quartile. In women with a high total physical activity score (>174 min/day), WHR was lower in the lowest IGF-I quartiles.
  
  
  CONCLUSIONS
  In this large cohort of community dwelling older people, we observed lower serum IGF-I levels in the higher age categories. A low serum IGF-I was associated with significantly lower measurements of body composition, such as BMI, skinfolds and WHR. These results do not support previous findings that high IGF-I levels are favourable for a healthy body composition in community dwelling older people.
authors.affiliation: Department of Endocrinology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Sigridur
authors.initials: S
authors.lastname: Jakobsdóttir
authors.forename: I Caroline
authors.initials: IC
authors.lastname: van Nieuwpoort
authors.forename: Laura A
authors.initials: LA
authors.lastname: Schaap
authors.forename: Natasja M
authors.initials: NM
authors.lastname: van Schoor
authors.forename: Paul
authors.initials: P
authors.lastname: Lips
authors.forename: Madeleine L
authors.initials: ML
authors.lastname: Drent
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition / Q000502:physiology*; D015519:Bone Density / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000378:metabolism; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012111:Residence Characteristics
chemical_list: D007334:Insulin-Like Growth Factor I