title: Simultaneous measurement of serum testosterone and dihydrotestosterone by liquid chromatography-tandem mass spectrometry.
abstract: BACKGROUND
  Recent reports have described inherent problems with androgen immunoassays compared with mass spectrometry analyses.
  
  
  METHODS
  We developed a method for measuring serum testosterone (T) and 5alpha-dihydrotestosterone (DHT) simultaneously via liquid-liquid extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with positive-mode electrospray ionization.
  
  
  RESULTS
  The DHT and T calibrators showed a linear response from 0.069 nmol/L to 34.4 nmol/L and 69.3 nmol/L, respectively. T interference in the DHT assay and vice versa were negligible. Within- and between-run imprecision values were <5% for both analytes. Percent recoveries of T and DHT spiked into samples at concentrations spanning the calibration curve were 100%-113% and 98%-107%, respectively. The lower limit of quantification was 0.069 nmol/L for both steroids. Serum T concentrations measured by LC-MS/MS were different from those obtained by RIA, especially at lower T concentrations. Serum DHT concentrations measured by LC-MS/MS were markedly lower than those generated by RIA because of the nonselectivity of the RIA without chromatography. The reference intervals (mean +/- 2 SDs) determined for T and DHT were 9.2-33.7 nmol/L and 0.47-2.65 nmol/L, respectively, for 113 healthy adult men and 0.33-2.02 nmol/L and 0.09-0.91 nmol/L, respectively, for 133 healthy premenopausal women.
  
  
  CONCLUSIONS
  We have developed and validated a selective and precise method for simultaneous measurements of serum T and DHT that can be adopted for routine measurements of these androgens in health and disease in men and women.
authors.affiliation: General Clinical Research Center, Division of Endocrinology and Metabolism, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, CA 90509, USA.
authors.forename: Steve
authors.initials: S
authors.lastname: Shiraishi
authors.forename: Paul W N
authors.initials: PW
authors.lastname: Lee
authors.forename: Andrew
authors.initials: A
authors.lastname: Leung
authors.forename: Victor H H
authors.initials: VH
authors.lastname: Goh
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Swerdloff
authors.forename: Christina
authors.initials: C
authors.lastname: Wang
mesh_terms: D000328:Adult; D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D013196:Dihydrotestosterone / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D012016:Reference Values; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013739:Testosterone / Q000097:blood*
chemical_list: D013196:Dihydrotestosterone; D013739:Testosterone