title: In men older than 70 years, total testosterone remains stable while free testosterone declines with age. The Health in Men Study.
abstract: OBJECTIVE
  An age-related decline in serum total and free testosterone concentration may contribute to ill health in men, but limited data are available for men > 70 years of age. We sought to determine the distribution and associations of reduced testosterone concentrations in older men.
  
  
  METHODS
  The Health in Men Study is a community-representative prospective cohort investigation of 4263 men aged > or = 70 years. Cross-sectional hormone data from 3645 men were analysed.
  
  
  METHODS
  Early morning sera were assayed for total testosterone, sex hormone binding globulin (SHBG) and LH. Free testosterone was calculated using the Vermeulen method.
  
  
  RESULTS
  Mean (+/- s.d.) serum total testosterone was 15.4 +/- 5.6 nmol/l (444 +/- 162 ng/dl), SHBG 42.4 +/- 16.7 nmol/l and free testosterone 278 +/- 96 pmol/l (8.01 +/- 2.78 ng/dl). Total testosterone correlated with SHBG (Spearman's r = 0.6, P < 0.0001). LH and SHBG increased with age (r = 0.2, P < 0.0001 for both). Instead of declining, total testosterone increased marginally (r = 0.04, P = 0.007) whilst free testosterone declined with age (r = -0.1, P < 0.0001). Free testosterone was inversely correlated with LH (r = -0.1, P < 0.0001). In multivariate analyses, increasing age, body mass index (BMI) and LH were associated with lower free testosterone.
  
  
  CONCLUSIONS
  In men aged 70-89 years, modulation of androgen action may occur via an age-related increase in SHBG and reduction in free testosterone without a decline in total testosterone concentration. Increasing age, BMI and LH are independently associated with lower free testosterone. Further investigation would be required to assess the clinical consequences of low serum free testosterone, particularly in older men in whom total testosterone may be preserved.
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Crawley, Western Australia, Australia. byeap@cyllene.uwa.edu.au
authors.forename: Bu B
authors.initials: BB
authors.lastname: Yeap
authors.forename: Osvaldo P
authors.initials: OP
authors.lastname: Almeida
authors.forename: Zoë
authors.initials: Z
authors.lastname: Hyde
authors.forename: Paul E
authors.initials: PE
authors.lastname: Norman
authors.forename: S A Paul
authors.initials: SA
authors.lastname: Chubb
authors.forename: Konrad
authors.initials: K
authors.lastname: Jamrozik
authors.forename: Leon
authors.initials: L
authors.lastname: Flicker
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005500:Follow-Up Studies; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D015999:Multivariate Analysis; D012044:Regression Analysis; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000097:blood*; D014904:Western Australia
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D007986:Luteinizing Hormone