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Reproducibility and Accuracy of Measurements of Free and Total Prostate-Specific Antigen in Serum vs Plasma after Long-Term Storage at -20 {degrees}C.

Ulmert, David LU ; Becker, Charlotte LU ; Nilsson, Jan-Ake; Piironen, Timo; Björk, Thomas LU ; Hugosson, Jonas; Berglund, Göran LU and Lilja, Hans LU (2006) In Clinical Chemistry 52(2). p.235-239
Abstract
Background: Long-term frozen storage may alter the results of prostate-specific antigen (PSA) measurements, mainly because of degradation of free PSA (fPSA) in vitro. We compared the effects of long-term storage on fPSA, total PSA (tPSA), and complexed PSA (cPSA) in serum vs EDTA-plasma samples. Methods: We measured fPSA and tPSA concentrations in matched pairs of archival serum and EDTA-plasma samples (stored frozen at -20 degrees C for 20 years) from a large population-based cohort in Malmo, Sweden. We also compared concentrations in age-matched men with those in samples not subjected to long-term storage, obtained from participants in a population-based study of prostate cancer screening in Goteborg, Sweden. These contemporary samples... (More)
Background: Long-term frozen storage may alter the results of prostate-specific antigen (PSA) measurements, mainly because of degradation of free PSA (fPSA) in vitro. We compared the effects of long-term storage on fPSA, total PSA (tPSA), and complexed PSA (cPSA) in serum vs EDTA-plasma samples. Methods: We measured fPSA and tPSA concentrations in matched pairs of archival serum and EDTA-plasma samples (stored frozen at -20 degrees C for 20 years) from a large population-based cohort in Malmo, Sweden. We also compared concentrations in age-matched men with those in samples not subjected to long-term storage, obtained from participants in a population-based study of prostate cancer screening in Goteborg, Sweden. These contemporary samples were handled according to standardized preanalytical. and analytical protocols aimed at minimizing in vitro degradation. tPSA and fPSA measurements were performed with a commercial assay (Prostatus Dual Assay; Perkin-Elmer Life Sciences). Results: Concentrations of tPSA and fPSA and calculated cPSA (tPSA-fPSA) in archival plasma were not significantly different from those in contemporary serum from age-matched men. In archival serum, however, random variability of fPSA was higher vs plasma than in contemporary samples, whereas systematic error of fPSA analyses was similarly small in archival and contemporary serum and plasma. Conclusions: Concentrations of tPSA and calculated cPSA were highly stable in plasma and serum samples subjected to long-term storage at -20 degrees C. Greater random variability, rather than a systematic decrease, may explain differences in fPSA analyses observed in archival serum. (c) 2006 American Association for Clinical Chemistry. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Clinical Chemistry
volume
52
issue
2
pages
235 - 239
publisher
American Association for Clinical Chemistry
external identifiers
  • pmid:16384894
  • wos:000235069600009
  • scopus:31844447749
ISSN
0009-9147
DOI
10.1373/clinchem.2005.050641
language
English
LU publication?
yes
id
3e140d26-569f-46d8-aef5-c6d371d87410 (old id 148425)
alternative location
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16384894&dopt=Abstract
date added to LUP
2007-07-06 09:43:34
date last changed
2019-06-25 01:36:23
@article{3e140d26-569f-46d8-aef5-c6d371d87410,
  abstract     = {Background: Long-term frozen storage may alter the results of prostate-specific antigen (PSA) measurements, mainly because of degradation of free PSA (fPSA) in vitro. We compared the effects of long-term storage on fPSA, total PSA (tPSA), and complexed PSA (cPSA) in serum vs EDTA-plasma samples. Methods: We measured fPSA and tPSA concentrations in matched pairs of archival serum and EDTA-plasma samples (stored frozen at -20 degrees C for 20 years) from a large population-based cohort in Malmo, Sweden. We also compared concentrations in age-matched men with those in samples not subjected to long-term storage, obtained from participants in a population-based study of prostate cancer screening in Goteborg, Sweden. These contemporary samples were handled according to standardized preanalytical. and analytical protocols aimed at minimizing in vitro degradation. tPSA and fPSA measurements were performed with a commercial assay (Prostatus Dual Assay; Perkin-Elmer Life Sciences). Results: Concentrations of tPSA and fPSA and calculated cPSA (tPSA-fPSA) in archival plasma were not significantly different from those in contemporary serum from age-matched men. In archival serum, however, random variability of fPSA was higher vs plasma than in contemporary samples, whereas systematic error of fPSA analyses was similarly small in archival and contemporary serum and plasma. Conclusions: Concentrations of tPSA and calculated cPSA were highly stable in plasma and serum samples subjected to long-term storage at -20 degrees C. Greater random variability, rather than a systematic decrease, may explain differences in fPSA analyses observed in archival serum. (c) 2006 American Association for Clinical Chemistry.},
  author       = {Ulmert, David and Becker, Charlotte and Nilsson, Jan-Ake and Piironen, Timo and Björk, Thomas and Hugosson, Jonas and Berglund, Göran and Lilja, Hans},
  issn         = {0009-9147},
  language     = {eng},
  number       = {2},
  pages        = {235--239},
  publisher    = {American Association for Clinical Chemistry},
  series       = {Clinical Chemistry},
  title        = {Reproducibility and Accuracy of Measurements of Free and Total Prostate-Specific Antigen in Serum vs Plasma after Long-Term Storage at -20 {degrees}C.},
  url          = {http://dx.doi.org/10.1373/clinchem.2005.050641},
  volume       = {52},
  year         = {2006},
}