title: Testosterone measured by 10 immunoassays and by isotope-dilution gas chromatography-mass spectrometry in sera from 116 men, women, and children.
abstract: BACKGROUND
  Commercially available testosterone immunoassays give divergent results, especially at the low concentrations seen in women. We compared immunoassays and a nonimmunochemical method that could quantify low testosterone concentrations.
  
  
  METHODS
  We measured serum testosterone in 50 men, 55 women, and 11 children with use of eight nonisotopic immunoassays, two isotopic immunoassays, and isotope-dilution gas chromatography-mass spectrometry (ID/GC-MS).
  
  
  RESULTS
  Compared with ID/GC-MS, 7 of the 10 immunoassays tested overestimated testosterone concentrations in samples from women; mean immunoassay results were 46% above those obtained by ID/GC-MS. The immunoassays underestimated testosterone concentrations in samples from men, giving mean results 12% below those obtained by ID/GC-MS. In women, at concentrations of 0.6-7.2 nmol/L, 3 of the 10 immunoassays gave positive mean differences >2.0 nmol/L (range, -0.7 to 3.3 nmol/L) compared with ID/GC-MS; in men at concentrations of 8.2-58 nmol/L, 3 of the 10 immunoassays tested gave mean differences >4.0 nmol/L (range, -4.8 to 2.6 nmol/L).
  
  
  CONCLUSIONS
  None of the immunoassays tested was sufficiently reliable for the investigation of sera from children and women, in whom very low (0.17 nmol/L) and low (<1.7 nmol/L) testosterone concentrations are expected.
authors.affiliation: Hormonology Laboratory, A. Béclère Hospital, 92141 Clamart, France.
authors.forename: Joëlle
authors.initials: J
authors.lastname: Taieb
authors.forename: Bruno
authors.initials: B
authors.lastname: Mathian
authors.forename: Françoise
authors.initials: F
authors.lastname: Millot
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Patricot
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Mathieu
authors.forename: Nicole
authors.initials: N
authors.lastname: Queyrel
authors.forename: Isabelle
authors.initials: I
authors.lastname: Lacroix
authors.forename: Claude
authors.initials: C
authors.lastname: Somma-Delpero
authors.forename: Philippe
authors.initials: P
authors.lastname: Boudou
mesh_terms: D000328:Adult; D000368:Aged; D001322:Autoanalysis / Q000379:methods; D002648:Child; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008297:Male; D008875:Middle Aged; D011865:Radioisotope Dilution Technique; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone