title: Blood levels of free-PSA but not complex-PSA significantly correlates to prostate release of PSA in semen in young men, while blood levels of complex-PSA, but not free-PSA increase with age.
abstract: BACKGROUND
  The proportion of free- and complex-prostate specific antigen (PSA) in serum is used for differentiating between benign and malignant prostate disease. To further understand the physiological relationship between PSA in seminal plasma and blood, we have analyzed free-PSA (fPSA) and complex-PSA (cPSA) in blood and PSA in seminal plasma in young healthy men. We also compared age-related changes of PSA-forms in blood from young versus older men.
  
  
  METHODS
  Total-PSA (tPSA), fPSA, and cPSA were measured in (i) blood and semen from 289 male conscripts (mean age 18.1 years) and in (ii) blood from a representative population of 1,389 men (mean age 46.5 years) without diagnosis of prostate cancer (PCa) during long-term follow-up.
  
  
  RESULTS
  fPSA in serum (r = 0.40, P < 0.0001) but not cPSA (r = 0.09, P = 0.11), correlates to PSA in seminal fluid. fPSA levels in blood in young (geometric mean: 0.20 ng/ml) versus middle-aged men (geometric mean: 0.18 ng/ml) was not different (P = 0.06), whereas cPSA in middle-aged men (geometric mean: 0.38 ng/ml) was higher (P < 0.0001) than in young men (geometric mean: 0.28 ng/ml).
  
  
  CONCLUSIONS
  fPSA in blood, but not cPSA, is associated to PSA in semen ( approximately 17% co-variation). In blood cPSA, but not fPSA, increase with age in healthy men, which may reflect an increasing incidence of prostate disease.
authors.affiliation: Department of Laboratory Medicine, Division of Clinical Chemistry, Lund University, Malmö University Hospital, Malmö, Sweden. charlotta.savblom@med.lu.se
authors.forename: Charlotta
authors.initials: C
authors.lastname: Sävblom
authors.forename: Johan
authors.initials: J
authors.lastname: Malm
authors.forename: Aleksander
authors.initials: A
authors.lastname: Giwercman
authors.forename: Jan-Ake
authors.initials: JA
authors.lastname: Nilsson
authors.forename: Göran
authors.initials: G
authors.lastname: Berglund
authors.forename: Hans
authors.initials: H
authors.lastname: Lilja
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood* / Q000378:metabolism; D012661:Semen / Q000378:metabolism*; D000515:alpha 1-Antitrypsin / Q000032:analysis
chemical_list: D000515:alpha 1-Antitrypsin; D017430:Prostate-Specific Antigen