title: Identification of late-onset hypogonadism in middle-aged and elderly men.
abstract: BACKGROUND
  The association between aging-related testosterone deficiency and late-onset hypogonadism in men remains a controversial concept. We sought evidence-based criteria for identifying late-onset hypogonadism in the general population on the basis of an association between symptoms and a low testosterone level.
  
  
  METHODS
  We surveyed a random population sample of 3369 men between the ages of 40 and 79 years at eight European centers. Using questionnaires, we collected data with regard to the subjects' general, sexual, physical, and psychological health. Levels of total testosterone were measured in morning blood samples by mass spectrometry, and free testosterone levels were calculated with the use of Vermeulen's formula. Data were randomly split into separate training and validation sets for confirmatory analyses.
  
  
  RESULTS
  In the training set, symptoms of poor morning erection, low sexual desire, erectile dysfunction, inability to perform vigorous activity, depression, and fatigue were significantly related to the testosterone level. Increased probabilities of the three sexual symptoms and limited physical vigor were discernible with decreased testosterone levels (ranges, 8.0 to 13.0 nmol per liter [2.3 to 3.7 ng per milliliter] for total testosterone and 160 to 280 pmol per liter [46 to 81 pg per milliliter] for free testosterone). However, only the three sexual symptoms had a syndromic association with decreased testosterone levels. An inverse relationship between an increasing number of sexual symptoms and a decreasing testosterone level was observed. These relationships were independently confirmed in the validation set, in which the strengths of the association between symptoms and low testosterone levels determined the minimum criteria necessary to identify late-onset hypogonadism.
  
  
  CONCLUSIONS
  Late-onset hypogonadism can be defined by the presence of at least three sexual symptoms associated with a total testosterone level of less than 11 nmol per liter (3.2 ng per milliliter) and a free testosterone level of less than 220 pmol per liter (64 pg per milliliter).
authors.affiliation: Andrology Research Unit, Developmental and Regenerative Biomedicine Research Group, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom. frederick.wu@manchester.ac.uk
authors.forename: Frederick C W
authors.initials: FC
authors.lastname: Wu
authors.forename: Abdelouahid
authors.initials: A
authors.lastname: Tajar
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Beynon
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Pye
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Silman
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Finn
authors.forename: Terence W
authors.initials: TW
authors.lastname: O'Neill
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Bartfai
authors.forename: Felipe F
authors.initials: FF
authors.lastname: Casanueva
authors.forename: Gianni
authors.initials: G
authors.lastname: Forti
authors.forename: Aleksander
authors.initials: A
authors.lastname: Giwercman
authors.forename: Thang S
authors.initials: TS
authors.lastname: Han
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Kula
authors.forename: Michael E J
authors.initials: ME
authors.lastname: Lean
authors.forename: Neil
authors.initials: N
authors.lastname: Pendleton
authors.forename: Margus
authors.initials: M
authors.lastname: Punab
authors.forename: Steven
authors.initials: S
authors.lastname: Boonen
authors.forename: Dirk
authors.initials: D
authors.lastname: Vanderschueren
authors.forename: Fernand
authors.initials: F
authors.lastname: Labrie
authors.forename: Ilpo T
authors.initials: IT
authors.lastname: Huhtaniemi
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D017668:Age of Onset; D000368:Aged; D003863:Depression / Q000209:etiology*; D007172:Erectile Dysfunction / Q000209:etiology*; D005060:Europe / Q000453:epidemiology; D005221:Fatigue / Q000209:etiology*; D006306:Health Surveys; D006801:Humans; D007006:Hypogonadism / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology; D007989:Libido; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011795:Surveys and Questionnaires; D013739:Testosterone / Q000097:blood / Q000172:deficiency*
chemical_list: D013739:Testosterone