title: Analytical performance and clinical validity of two free prostate-specific antigen assays compared.
abstract: We compared two recently introduced commercial assays (CanAg and Immulite) for measuring free prostate-specific antigen (f-PSA), total PSA (t-PSA), and the ratio of t-PSA/f-PSA (f-PSA%) in control materials and sera of 54 healthy men, 50 patients with benign prostatic hyperplasia (BPH), and 45 patients with prostate cancer (PCa). The lower detection limits for f-PSA were 0.038 microgram/L and 0.004 microgram/L for the CanAg and Immulite assays, respectively. The within-run and between-day precisions of the Immulite assay were < 5%; the CanAg assay showed a poorer precision. Whereas f-PSA values differed between controls and patients but not between BPH and PCa patients, the f-PSA% values were lower in PCa patients than in BPH patients and controls. The receiver-operating characteristic (ROC) curve showed an improved diagnostic power of f-PSA% compared with t-PSA to discriminate between BPH and PCa. Discrimination limits of 16% (CanAg assay), and 15% (Immulite assay) are recommended for f-PSA%.
authors.affiliation: Department of Urology, University Hospital Charité, Humboldt University, Berlin, Germany. jung@rz.charite.hu-berlin.de
authors.forename: K
authors.initials: K
authors.lastname: Jung
authors.forename: C
authors.initials: C
authors.lastname: Stephan
authors.forename: M
authors.initials: M
authors.lastname: Lein
authors.forename: W
authors.initials: W
authors.lastname: Henke
authors.forename: D
authors.initials: D
authors.lastname: Schnorr
authors.forename: B
authors.initials: B
authors.lastname: Brux
authors.forename: P
authors.initials: P
authors.lastname: Schürenkämper
authors.forename: S A
authors.initials: SA
authors.lastname: Loening
mesh_terms: D001322:Autoanalysis; D006801:Humans; D007118:Immunoassay / Q000706:statistics & numerical data*; D007124:Immunoenzyme Techniques / Q000706:statistics & numerical data; D008163:Luminescent Measurements; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis; D012372:ROC Curve; D011933:Reagent Kits, Diagnostic / Q000706:statistics & numerical data*; D012680:Sensitivity and Specificity
chemical_list: D011933:Reagent Kits, Diagnostic; D017430:Prostate-Specific Antigen