title: Hormonal and biochemical determinants of trabecular microstructure at the ultradistal radius in women and men.
abstract: BACKGROUND
  Using high-resolution three-dimensional peripheral quantitative computed tomography (3D-pQCT) imaging, we recently described sex and age effects on bone microstructure at the ultradistal radius in men and women. Although bone volume/tissue volume decreased with age in both sexes, changes in trabecular number (TbN) and thickness (TbTh) in men were complex, with evidence for conversion of thick trabeculae into more numerous, thinner trabeculae in young men.
  
  
  OBJECTIVE
  Our objective was to define the relationship between hormonal and bone turnover variables and trabecular microstructure at the ultradistal radius.
  
  
  METHODS
  We conducted a population-based, cross-sectional study in the general community that included 205 women and 269 men, aged 21-97 yr.
  
  
  METHODS
  We measured correlation of bone volume/tissue volume, TbN, TbTh, and trabecular separation with hormonal and bone turnover variables.
  
  
  RESULTS
  In young men (20-39 yr), TbTh and TbN were associated with serum IGF-I levels (r = 0.31, P < 0.05 and r = -0.35, P < 0.01, respectively). No associations were found between sex steroid levels (bioavailable estradiol or testosterone) or biochemical markers of bone turnover and trabecular parameters in young men or women. By contrast, in elderly men and women (>60 yr), sex steroids were the most consistently associated with trabecular microstructure, and bone turnover markers were variably associated with these parameters.
  
  
  CONCLUSIONS
  In young men, the apparent conversion of thick trabeculae into more numerous, thinner trabeculae is most closely associated with declining IGF-I levels. By contrast, sex steroids are the major hormonal determinants of trabecular microstructure in elderly men and women.
authors.affiliation: Mayo Clinic, Endocrine Research Unit, 200 First Street SW, 5-194 Joseph, Rochester, Minnesota 55905, USA. khosla.sundeep@mayo.edu
authors.forename: Sundeep
authors.initials: S
authors.lastname: Khosla
authors.forename: L Joseph
authors.initials: LJ
authors.lastname: Melton
authors.forename: Sara J
authors.initials: SJ
authors.lastname: Achenbach
authors.forename: Ann L
authors.initials: AL
authors.lastname: Oberg
authors.forename: B Lawrence
authors.initials: BL
authors.lastname: Riggs
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D015519:Bone Density; D003430:Cross-Sectional Studies; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D014129:Trabecular Meshwork / Q000254:growth & development / Q000648:ultrastructure*
chemical_list: D012739:Gonadal Steroid Hormones; D007334:Insulin-Like Growth Factor I