title: Factors influencing the ratio of free to total prostate-specific antigen in serum.
abstract: The ratio of free prostate-specific antigen (f-PSA) to total PSA (t-PSA) in serum, calculated as percent free PSA (f-PSA%), is lower in patients with prostate carcinoma (PCa) than in patients with benign prostate hyperplasia (BPH). This parameter facilitates discrimination between the 2 groups of patients, but there is an overlapping of data. A better understanding of factors influencing this ratio is of practical importance. Therefore, f-PSA% was measured in controls and patients suffering from BPH, PCa and chronic prostatic inflammation with t-PSA concentrations up to 20 microg/l using the IMMULITE assays. The relationships of f-PSA% to clinical situation, age, prostate volume, kind of treatment, and stage and grade of tumor were calculated. Compared with controls or BPH patients, mean f-PSA% values were reduced in PCa patients and in patients with chronic prostatic inflammation. The prostate volume was the most important factor to influence f-PSA%. The difference of f-PSA% between PCa and BPH patients with prostate volumes smaller than 40 cm3 was lost if the prostate volumes exceeded 40 cm3. No relationship of f-PSA% to pTNM stage or grade of tumor was observed. In contrast to t-PSA concentrations, the f-PSA% values were not age-dependent and were not influenced by any kind of treatment in BPH and PCa patients either, which simplifies the use of f-PSA% compared with t-PSA. Thus, for using f-PSA% in clinical practice and for interpreting the data correctly, the advantages shown have to be considered along with the potential limitations of f-PSA%.
authors.affiliation: Department of Urology, University Hospital Charité, Humboldt University, Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Meyer
authors.forename: K
authors.initials: K
authors.lastname: Jung
authors.forename: M
authors.initials: M
authors.lastname: Lein
authors.forename: B
authors.initials: B
authors.lastname: Rudolph
authors.forename: D
authors.initials: D
authors.lastname: Schnorr
authors.forename: S A
authors.initials: SA
authors.lastname: Loening
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D018120:Finasteride / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size / Q000502:physiology; D011467:Prostate / Q000033:anatomy & histology / Q000601:surgery; D017430:Prostate-Specific Antigen / Q000097:blood*; D011469:Prostatic Diseases / Q000097:blood / Q000628:therapy; D011485:Protein Binding; D012016:Reference Values; D000514:alpha 1-Antichymotrypsin / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D000514:alpha 1-Antichymotrypsin; D018120:Finasteride; D017430:Prostate-Specific Antigen