title: Stability of [-2]Pro-PSA in whole blood and serum: analysis for optimal measurement conditions.
abstract: BACKGROUND
  The clinical usefulness of [-2]pro-PSA (where PSA is prostate-specific antigen) in prostate cancer diagnosis has been emphasized in recent studies. To determine proper blood sample handling conditions for [-2]pro-PSA evaluation, we analyzed the preanalytical stability of [-2]pro-PSA.
  
  
  METHODS
  Blood samples from 22 Japanese males were stored under various conditions before total PSA (tPSA), free PSA, and [-2]pro-PSA concentrations were measured, and the preanalytical stability of [-2]pro-PSA and the changes in the Prostate Health Index (phi) were assessed.
  
  
  RESULTS
  [-2]Pro-PSA was stable in serum for at least 24 hr at both room temperature (RT) and at 4°C. However, [-2]pro-PSA levels in whole blood increased rapidly over time, particularly at RT. Mean recovery (%) of [-2]pro-PSA in whole blood at RT was >110% at 1 hr after drawing of blood. The phi tended to increase over time in a pattern similar to the change in[-2]pro-PSA.
  
  
  CONCLUSIONS
  Preanalytical stability was lower for [-2]pro-PSA than for free PSA or tPSA. Whole-blood [-2]pro-PSA increased in a time-dependent manner, particularly at RT. Thus, whole blood samples collected at RT should be centrifuged within 1 hr after drawing. The [-2]pro-PSA in serum is stable for at least 24 hr at both RT and at 4°C.
authors.affiliation: Department of Nephro-urology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Igawa
authors.forename: Kosuke
authors.initials: K
authors.lastname: Takehara
authors.forename: Toru
authors.initials: T
authors.lastname: Onita
authors.forename: Kazuto
authors.initials: K
authors.lastname: Ito
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai
mesh_terms: D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D055550:Protein Stability; D044967:Serum / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors
chemical_list: D017430:Prostate-Specific Antigen
keywords: Prostate Health Index; [−2]pro-PSA; free PSA; preanalytical stability; prostate cancer