title: Validation of a testosterone and dihydrotestosterone liquid chromatography tandem mass spectrometry assay: Interference and comparison with established methods.
abstract: Testosterone (T) and its metabolite dihydrotestosterone (DHT) are androgens with different biologic profiles. T and DHT measurements are required for assessment of patients with ambiguous genitalia, hirsutism, during 5 alpha reductase treatment of prostate disorders, and new androgen formulations. Our laboratory has developed and validated a method to simultaneously measure serum T and DHT with liquid chromatography tandem mass spectrometry (LC-MS/MS) for use in a clinical chemistry laboratory. Analysis of sera from blood collected in tubes containing clot activator gave results of T that were fourfold higher than blood collected in plain tubes. Changing the ion pair selected for monitoring eliminated this interference by clot activators. Blood collected in fluoride-coated tubes gave serum T and DHT levels that were 20 and 15% lower, respectively than levels measured in blood collected in plain tubes (no additives). Addition of T enanthate to blood collected in plain tubes caused a dose related increase serum T levels due to the action of non-specific esterases in the red cells. This esterase activity could be avoided by using fluoride tubes for blood collection. Serum DHT levels were consistently lower when measured by LC-MS/MS versus radioimmunoassay. The differences were concentration dependent and the variance for the difference was large when serum DHT concentration was low. Celite chromatograph prior to radioimmunoassay reduced the differences between the two methods, thus confirming that higher levels of DHT obtained by immunoassays were probably due to interfering substances which were partially removed by Celite chromatography.
authors.affiliation: General Clinical Research Center, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, 1000 Carson Street, Torrance, CA 90509, USA. wang@labiomed.org
authors.forename: Christina
authors.initials: C
authors.lastname: Wang
authors.forename: Steve
authors.initials: S
authors.lastname: Shiraishi
authors.forename: Andrew
authors.initials: A
authors.lastname: Leung
authors.forename: Sima
authors.initials: S
authors.lastname: Baravarian
authors.forename: Laura
authors.initials: L
authors.lastname: Hull
authors.forename: Victor
authors.initials: V
authors.lastname: Goh
authors.forename: Paul W N
authors.initials: PW
authors.lastname: Lee
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Swerdloff
mesh_terms: D000328:Adult; D002853:Chromatography, Liquid / Q000379:methods*; D013196:Dihydrotestosterone / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay / Q000379:methods; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013739:Testosterone / Q000097:blood*; D055815:Young Adult
chemical_list: D013196:Dihydrotestosterone; D013739:Testosterone