title: Body composition, sex steroids, IGF-1, and bone mineral status in aging men.
abstract: BACKGROUND
  Bone loss in elderly men is associated with changes in body composition and reduced secretion of endogenous anabolizing hormones. The independent influences of body composition and endocrine factors on male bone metabolism, however, are unclear.
  
  
  METHODS
  Bone mass density (BMD) (bone mass content [BMC, g]/projected bone area [BA, cm2]) at different skeletal sites, skeletal muscle, and body fat mass were measured by dual-energy X-ray absorptiometry in 129 men aged 20 to 95 years. Free testosterone, 17-beta-estradiol, dehydroepiandrosterone-sulfate, and insulin-like growth factor 1 (IGF-1) serum concentrations were measured. Because BMD may fail to control for differences in skeletal size, the associations of bone mass with body composition and hormones were studied by comparing BMD regression models incorporating age and knee height only with BMC regression models also incorporating BA.
  
  
  RESULTS
  Skeletal muscle had close associations (p at least < .01) with BMD and BMC at almost all skeletal sites, but the strength of these associations was generally reduced in BMC with respect to BMD models. Weak associations (p < .05) were found in both models for fatness with femoral bone and for 17-beta-estradiol with total body and femoral bone. The association of 17-beta-estradiol with spinal bone was significant (p < .05) in the BMD but not in the BMC model. No association of BMC or BMD with androgens and IGF-1 reached significancy.
  
  
  CONCLUSIONS
  Skeletal muscle may be more important than fatness and anabolizing hormones in preserving bone mass in elderly men. In contrast to traditional belief, estrogens may be more important than androgens and IGF-1 in male bone metabolism.
authors.affiliation: Department of Internal Medicine, Cardioangiology, and Hepatology, S. Orsola-Malpighi Hospital, University of Bologna, Italy. ravaglia@almadns.unibo.it
authors.forename: G
authors.initials: G
authors.lastname: Ravaglia
authors.forename: P
authors.initials: P
authors.lastname: Forti
authors.forename: F
authors.initials: F
authors.lastname: Maioli
authors.forename: B
authors.initials: B
authors.lastname: Nesi
authors.forename: L
authors.initials: L
authors.lastname: Pratelli
authors.forename: D
authors.initials: D
authors.lastname: Cucinotta
authors.forename: L
authors.initials: L
authors.lastname: Bastagli
authors.forename: G
authors.initials: G
authors.lastname: Cavalli
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood / Q000502:physiology*; D045930:Anabolic Agents / Q000097:blood; D000728:Androgens / Q000097:blood*; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology*; D019314:Dehydroepiandrosterone Sulfate / Q000097:blood; D004958:Estradiol / Q000097:blood; D004967:Estrogens / Q000097:blood*; D005269:Femur / Q000033:anatomy & histology; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D007719:Knee Joint / Q000033:anatomy & histology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D012044:Regression Analysis; D013131:Spine / Q000033:anatomy & histology; D013739:Testosterone / Q000097:blood
chemical_list: D045930:Anabolic Agents; D000728:Androgens; D004967:Estrogens; D013739:Testosterone; D004958:Estradiol; D019314:Dehydroepiandrosterone Sulfate; D007334:Insulin-Like Growth Factor I