title: To what extent are free testosterone (FT) values reproducible between the two Washingtons, and can calculated FT be used in lieu of expensive direct measurements?
abstract: Free testosterone (FT) measurement by equilibrium dialysis and liquid chromatography-tandem mass spectroscopy (LCMS/MS) is the "gold standard." We hypothesized that calculated FT values could substitute for measured values; compared FT results reported by Walter Reed Army Medical Center (WRAMC), Washington, DC, with results reported by the Seattle Veterans Affairs Health Care System, Seattle, WA, for 3 patient groups; and evaluated the calculated FT values by gold-standard measurements. Groups 1 and 2 included samples from 54 patients evaluated in Seattle and 94 evaluated at a primary care clinic in Alaska whose samples were analyzed in Seattle, respectively, whose care resulted in ordering an FT measurement. Group 3 included samples from 64 patients evaluated in endocrine WRAMC clinics. Calculated FT values between the 2 facilities demonstrated a strong correlation (R2 = 0.98) for all 212 patients. In a comparison of calculated FT values with measured levels, group 3 had an R2 = 0.93; however, samples with FT values less than 50 pg/mL had a poorer correlation (R2 = 0.45). Calculated FT values may accurately reflect and be substituted in the clinical setting for gold-standard values when levels are more than 50 pg/mL.
authors.affiliation: Department of Pathology and Area Laboratory Services, Core Laboratory, Walter Reed Army Medical Center, Washington, DC, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: DeVan
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Bankson
authors.forename: Jude M
authors.initials: JM
authors.lastname: Abadie
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002624:Chemistry, Clinical / Q000379:methods*; D004219:District of Columbia; D005260:Female; D006801:Humans; D008875:Middle Aged; D011863:Radioimmunoassay; D015203:Reproducibility of Results; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D013739:Testosterone / Q000097:blood*; D014861:Washington
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone