title: When is bioavailable testosterone a redundant test in the diagnosis of hypogonadism in men?
abstract: OBJECTIVE
  Total testosterone (TT) is frequently prescribed with an SHBG and/or free or bioavailable testosterone measurement. Our objective was to identify a TT range for which subsequent SHBG measurement/calculation adds no additional clinical information.
  
  
  METHODS
  Study data were composed of 3955 sets of TT, SHBG and calculated bioavailable testosterone (cBAT) results from unscreened ambulatory male subjects, aged 18-99.
  
  
  RESULTS
  90% of mismatches between TT and cBAT were observed with TT levels between 6.5 and 13.0 nmol/L, with only slight age variation and no important change with albumin level. SHBG measurement restricted to male patients with TT between 6.5 and 13.0 nmol/L should enable reagent cost savings of over 55%.
  
  
  CONCLUSIONS
  We suggest that a TT level below 6.5 nmol/L or above 13.0 nmol/L provides sufficient useful information for ruling out hypogonadism in ambulatory adult males. This strategy of BAT testing should lead to significant time and cost savings.
authors.affiliation: Collaborative Research for Effective Diagnostics (CRED), Centre Hospitalier Universitaire de Sherbrooke, 3001 13e Avenue Nord, Sherbrooke, Quebec, Canada J1H 5N4.
authors.forename: Ionela
authors.initials: I
authors.lastname: Gheorghiu
authors.forename: Andriy
authors.initials: A
authors.lastname: Moshyk
authors.forename: Raymond
authors.initials: R
authors.lastname: Lepage
authors.forename: Charaf E
authors.initials: CE
authors.lastname: Ahnadi
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Grant
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000418:Albumins; D001682:Biological Availability; D003955:Diagnostic Tests, Routine / Q000191:economics / Q000379:methods* / Q000592:standards; D006801:Humans; D007006:Hypogonadism / Q000175:diagnosis* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013739:Testosterone / Q000032:analysis / Q000378:metabolism*
chemical_list: D000418:Albumins; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone