title: Salivary testosterone measurement by liquid chromatography tandem mass spectrometry in adult males and females.
abstract: BACKGROUND
  Salivary testosterone (Sal-T) may be a useful surrogate of serum free testosterone. The study aims were to use a novel liquid chromatography tandem mass spectrometry (LC-MS/MS) assay to determine whether Sal-T concentrations accurately reflect Sal-T concentrations in both sexes and to investigate practical aspects of sample collection.
  
  
  METHODS
  Saliva and serum samples were collected in 104 male and 91 female subjects. A more sensitive LC-MS/MS assay was developed to enable Sal-T quantitation in the low concentrations found in females. Saliva (200 µL) was extracted with 1 mL of methyl-tert-butyl ether following the addition of D5-testosterone. Quantitation was performed using a Waters TQ-S mass spectrometer.
  
  
  RESULTS
  The assay achieved a lower limit of quantification of 5 pmol/L, sufficiently sensitive to measure testosterone in female saliva. Sal-T showed a diurnal variation but samples taken at weekly and monthly intervals showed no significant differences. Sal-T was stable at ambient temperature for up to 5 days, after freeze-thawing and 3 years frozen storage. Reference intervals for Sal-T were 93-378 pmol/L in males and 5-46 pmol/L in females. Sal-T correlated significantly with serum calculated free-T in males (r = 0.71, P < 0.001) and in females (r = 0.39, P < 0.001).
  
  
  CONCLUSIONS
  These results confirm that testosterone can be reliably and accurately measured by LC-MS/MS in both adult male and female saliva samples. These results lay the foundation for further exploration of the clinical application of Sal- T as a reliable alternative to serum testosterone in the diagnosis and management of androgen disorders and assessment of androgen status in clinical research.
authors.affiliation: Department of Clinical Biochemistry, University Hospital of South Manchester, Manchester, UK.
authors.forename: B G
authors.initials: BG
authors.lastname: Keevil
authors.forename: P
authors.initials: P
authors.lastname: MacDonald
authors.forename: W
authors.initials: W
authors.lastname: Macdowall
authors.forename: D M
authors.initials: DM
authors.lastname: Lee
authors.forename: F C W
authors.initials: FC
authors.lastname: Wu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002853:Chromatography, Liquid / Q000379:methods*; D004355:Drug Stability; D004356:Drug Storage; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012463:Saliva / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013739:Testosterone / Q000032:analysis* / Q000097:blood; D013997:Time Factors; D055815:Young Adult
chemical_list: D013739:Testosterone
keywords: Steroid hormones; evaluation of new methods; laboratory methods; mass spectrometry; salivary analytes