title: [Analysis of salivary testosterone by liquid chromatography-tandem mass spectrometry: correlation with serum bioavailable testosterone and aging].
abstract: OBJECTIVE
  To demonstrate that the salivary testosterone (T) concentration measured by liquid chromatography tandem mass spectrometry (LC-MS/MS) is a sensitive biomarker of serum bioavailable testosterone (bio T) concentration and it's decrease with age.
  
  
  METHODS
  Saliva and blood samples were collected from healthy 53 Japanese men (16-66yr) three times a day (9: 00-10: 00, 13: 00-14: 00, 17: 00-18: 00). Salivary T and serum total T levels were compared with serum bio T levels fractionated with concanavaline A. All samples were measured by LC-MS/MS. The stability of salivary T concentrations stored at -70 degrees C for 2 months was also examined.
  
  
  RESULTS
  Salivary T levels correlated with bio T(r=0.88, n=158) better than total T did (r=0.71, n=159). The decrease of T concentration with age was observed in saliva of each sampling time. In total T, the decrease with age was weaker and was insignificant in the late afternoon. Salivary T was stable for 2 months at -70 degrees C and a freeze/thaw cycle (difference: average 3.7%, SD=8.4%, n=84).
  
  
  CONCLUSIONS
  Salivary T measured by LC-MS/MS is a reliable biomarker of T availability and its decrease with aging.
authors.affiliation: Department of Cognitive and Behavioral Science, the University of Tokyo, Meguro-ku, Tokyo 153-8902.
authors.forename: Kikue
authors.initials: K
authors.lastname: Sakaguchi
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Hasegawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001682:Biological Availability; D015415:Biomarkers / Q000032:analysis*; D002853:Chromatography, Liquid; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D012463:Saliva / Q000737:chemistry*; D013739:Testosterone / Q000032:analysis* / Q000097:blood*
chemical_list: D015415:Biomarkers; D013739:Testosterone