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In vitro stability of free prostate-specific antigen (PSA) and prostate- specific antigen (PSA) complexed to α1-antichymotrypsin in blood samples

Piironen, Timo ; Pettersson, Kim ; Suonpää, Mikko ; Stenman, Ulf Håkan ; Oesterling, Joseph E. ; Lövgren, Timo and Lilja, Hans LU orcid (1996) In Urology 48(6 SUPPL.). p.81-87
Abstract

Objectives. To study the in vitro stability of free and complexed forms of prostate specific antigen (PSA) in blood samples in order to establish guidelines for specimen handling, in particular for the clinical utility of the analysis of percentage free PSA. Methods. Blood samples were collected and processed to generate serum, heparin plasma, and EDTA plasma. Three different two-site immunoassays were used to measure the concentrations of total PSA (PSA-T), free form of PSA (PSA-F), and PSA-α1-antichymotrypsin complex (PSA-ACT) in order to determine the effect of repeated freezing and thawing, delayed separation of serum from blood cells, and stability during storage at 4°C and 30°C. Results. Five cycles of freezing and... (More)

Objectives. To study the in vitro stability of free and complexed forms of prostate specific antigen (PSA) in blood samples in order to establish guidelines for specimen handling, in particular for the clinical utility of the analysis of percentage free PSA. Methods. Blood samples were collected and processed to generate serum, heparin plasma, and EDTA plasma. Three different two-site immunoassays were used to measure the concentrations of total PSA (PSA-T), free form of PSA (PSA-F), and PSA-α1-antichymotrypsin complex (PSA-ACT) in order to determine the effect of repeated freezing and thawing, delayed separation of serum from blood cells, and stability during storage at 4°C and 30°C. Results. Five cycles of freezing and thawing introduced no statistically significant changes in the measured concentrations of PSA-T, PSA-F, or PSA-ACT. The effect of storing blood samples at room temperature for 1-6 h before separation of serum revealed a statistically significant decrease only for PSA-F after 5.5 h of storage (mean decrease 3.5%). PSA-T and PSA-ACT showed good stability in both serum and plasma samples, whereas PSA-F, after 1 week of storage at 4°C, decreased on average by 28.8%, 7.8%, and 5.6%, respectively, in serum, heparin plasma, and EDTA plasma. The decreases of PSA-F at 4°C were statistically significant (P < 0.05) relative to the controls (samples stored at -20°C) after storage for 23 h in serum, 86 h in heparin plasma, and 71 h in EDTA plasma. When the same samples were stored at 30°C for 24 h, only the mean decrease of PSA-F (4.8%) in serum was statistically significant. Conclusions. PSA-F in blood samples is less stable than PSA-ACT. It is not advisable to store samples on the clot, especially if time and temperature cannot be controlled. Serum samples should be stored frozen if not analyzed during the same day. After thawing, samples can be stored up to 23 h at 4°C prior to analysis. The use of plasma samples improves the stability of free PSA.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Urology
volume
48
issue
6 SUPPL.
pages
81 - 87
publisher
Elsevier
external identifiers
  • scopus:0030448714
  • pmid:8973706
ISSN
0090-4295
DOI
10.1016/S0090-4295(96)00616-4
language
English
LU publication?
yes
additional info
Funding Information: ACKNOWLEDGMENTS. The work was supported by grants from the Biomed 2 program, Area 4.1.7. (contract number BMH4-CT96-0453), the Swedish Medical Research Council (project number 79031, the Swedish Cancer Society (project number 3555), the Faculty of Medicine at Lund University, the Research Fund and the Cancer Research Fund at the University Hospital, the Crafoord Foundation, the Gunnar, Arvid, and Elisabeth Nilsson Foundation, the Foundation Urology Research in Malmo, and the Fundacion Frederic0 S.A.
id
f9c1af5c-a971-423d-b0c8-36349795d172
date added to LUP
2022-12-06 16:33:52
date last changed
2024-04-04 12:12:43
@article{f9c1af5c-a971-423d-b0c8-36349795d172,
  abstract     = {{<p>Objectives. To study the in vitro stability of free and complexed forms of prostate specific antigen (PSA) in blood samples in order to establish guidelines for specimen handling, in particular for the clinical utility of the analysis of percentage free PSA. Methods. Blood samples were collected and processed to generate serum, heparin plasma, and EDTA plasma. Three different two-site immunoassays were used to measure the concentrations of total PSA (PSA-T), free form of PSA (PSA-F), and PSA-α<sub>1</sub>-antichymotrypsin complex (PSA-ACT) in order to determine the effect of repeated freezing and thawing, delayed separation of serum from blood cells, and stability during storage at 4°C and 30°C. Results. Five cycles of freezing and thawing introduced no statistically significant changes in the measured concentrations of PSA-T, PSA-F, or PSA-ACT. The effect of storing blood samples at room temperature for 1-6 h before separation of serum revealed a statistically significant decrease only for PSA-F after 5.5 h of storage (mean decrease 3.5%). PSA-T and PSA-ACT showed good stability in both serum and plasma samples, whereas PSA-F, after 1 week of storage at 4°C, decreased on average by 28.8%, 7.8%, and 5.6%, respectively, in serum, heparin plasma, and EDTA plasma. The decreases of PSA-F at 4°C were statistically significant (P &lt; 0.05) relative to the controls (samples stored at -20°C) after storage for 23 h in serum, 86 h in heparin plasma, and 71 h in EDTA plasma. When the same samples were stored at 30°C for 24 h, only the mean decrease of PSA-F (4.8%) in serum was statistically significant. Conclusions. PSA-F in blood samples is less stable than PSA-ACT. It is not advisable to store samples on the clot, especially if time and temperature cannot be controlled. Serum samples should be stored frozen if not analyzed during the same day. After thawing, samples can be stored up to 23 h at 4°C prior to analysis. The use of plasma samples improves the stability of free PSA.</p>}},
  author       = {{Piironen, Timo and Pettersson, Kim and Suonpää, Mikko and Stenman, Ulf Håkan and Oesterling, Joseph E. and Lövgren, Timo and Lilja, Hans}},
  issn         = {{0090-4295}},
  language     = {{eng}},
  number       = {{6 SUPPL.}},
  pages        = {{81--87}},
  publisher    = {{Elsevier}},
  series       = {{Urology}},
  title        = {{In vitro stability of free prostate-specific antigen (PSA) and prostate- specific antigen (PSA) complexed to α<sub>1</sub>-antichymotrypsin in blood samples}},
  url          = {{http://dx.doi.org/10.1016/S0090-4295(96)00616-4}},
  doi          = {{10.1016/S0090-4295(96)00616-4}},
  volume       = {{48}},
  year         = {{1996}},
}