title: Changes in testosterone related to body composition in late midlife: Findings from the 1946 British birth cohort study.
abstract: OBJECTIVE
  Randomized trials in men with testosterone deficiency have provided evidence of short-term effects of testosterone therapy on muscle and fat mass but it is unclear whether this persists over a longer period or how testosterone affects women. We examined whether the midlife decline in testosterone relates to fat and lean mass in both sexes.
  
  
  METHODS
  Data were collected from 440 men and 560 women participating in the 1946 British birth cohort study with testosterone measured at 53 and/or 60-64 years. Fat and appendicular lean mass were measured at 60-64 years using dual-energy X-ray absorptiometry.
  
  
  RESULTS
  Mean free testosterone concentrations were lower at 60-64 than 53 years, by 26% in both sexes. At both ages testosterone was negatively associated with fat mass in men and positively associated in women. A larger decline in free testosterone was associated with higher fat mass in men but with lower fat mass among women. In contrast, declines in testosterone were not associated with lean mass in either sex.
  
  
  CONCLUSIONS
  Our findings suggest sex-divergent relationships between testosterone and fat mass and their distribution but do not support the hypothesis that midlife declines in testosterone lead to lower lean mass.
authors.affiliation: MRC Unit for Lifelong Health and Ageing at UCL, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Bann
authors.affiliation: Andrology Research Unit, School of Biomedicine, University of Manchester, Manchester, UK.
authors.forename: Frederick C W
authors.initials: FC
authors.lastname: Wu
authors.affiliation: Andrology Research Unit, School of Biomedicine, University of Manchester, Manchester, UK.
authors.forename: Brian
authors.initials: B
authors.lastname: Keevil
authors.affiliation: Department of Human Metabolism, The University of Sheffield, Sheffield, UK.
authors.forename: Hany
authors.initials: H
authors.lastname: Lashen
authors.affiliation: Department of Radiology, Central Manchester University Hospital NHS Foundation Trust, Manchester Academic Health Science Center, Manchester, UK.
authors.forename: Judith
authors.initials: J
authors.lastname: Adams
authors.affiliation: MRC Unit for Lifelong Health and Ageing at UCL, London, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Hardy
authors.affiliation: MRC Unit for Lifelong Health and Ageing at UCL, London, UK.
authors.forename: Graciela
authors.initials: G
authors.lastname: Muniz
authors.affiliation: MRC Unit for Lifelong Health and Ageing at UCL, London, UK.
authors.forename: Diana
authors.initials: D
authors.lastname: Kuh
authors.affiliation: School of Social and Community Medicine, Bristol University, Bristol, UK.
authors.forename: Yoav
authors.initials: Y
authors.lastname: Ben-Shlomo
authors.affiliation: MRC Epidemiology Unit, University of Cambridge, Cambridge, UK.
authors.forename: Ken K
authors.initials: KK
authors.lastname: Ong
mesh_terms: D015502:Absorptiometry, Photon; D000375:Aging / Q000502:physiology; D001823:Body Composition / Q000187:drug effects* / Q000502:physiology*; D015519:Bone Density / Q000187:drug effects / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013739:Testosterone / Q000097:blood*; D006113:United Kingdom
chemical_list: D013739:Testosterone