Storage conditions for serum for estimating prostate-specific antigen

Simm, Brett; Gleeson, Maree

doi:10.1093/clinchem/37.1.113

Cited by 24 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is clear from this evidence that the conditions met in routine practice must be carefully considered when requesting this test, and should highlight the caution needed when assessing published evidence about the use of fPSA and f/tPSA. The present results confirm other published reports that tPSA is a highly stable analyte [ 18–20]. If whole blood samples remain at room temperature for up to 24 h before processing, the results of subsequent assays on serum samples stored at either 4°C or −20°C are unaffected.…”

Section: Discussionsupporting

confidence: 90%

“…Most of the studies on PSA have used stored plasma or serum; there is well‐documented evidence that PSA is stable [ 18–20] and evidence about the stability of fPSA [ 21–24], but these data derive from studies in carefully controlled settings. There are very few data on the stability of fPSA and the calculated f/tPSA value in conditions likely to be met in routine clinical practice.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The stability of free and bound prostate‐specific antigen

et al. 1999

View full text Add to dashboard Cite

Objective To determine if the assay for free prostate specific antigen (fPSA) and the calculated ratio of fPSA to total PSA (f/tPSA) is stable in conditions likely to be met in routine clinical practice. Materials and methods Two blood samples were obtained from 27 patients attending a routine urology clinic. Sample 1 was centrifuged immediately, assayed for fPSA and tPSA, and the f/tPSA calculated. This sample was then stored at 4°C for 24 h, 48 h and 1 week, or at −20°C for 24 h, 1 week and 1 month before the assays for fPSA and tPSA were repeated. The second sample was left at room temperature for 24 h before assay and processing, as for sample 1. Results tPSA is a highly stable analyte; if whole blood samples are processed immediately, fPSA is stable for 24 h at 4°C and 1 month at −20°C. There was a significant reduction in the calculated f/tPSA in samples stored for ≥24 h at 4°C (P<0.01); if the sample was stored at −20°C the calculated f/tPSA was stable. After 24 h storage at room temperature, fPSA decreased by 6.3% and f/tPSA by 6.4%. Subsequent storage of serum at 4°C for 1 week resulted in a 25% decrease from the baseline value. After 1 month at −20°C the fPSA value was 13% lower than the baseline value. Conclusion These results indicate that if there is to be confidence in the accuracy of the f/tPSA value, then blood samples must be handled and processed correctly. Total PSA is sufficiently stable to permit whole blood samples to remain at room temperature for 24 h before serum is separated. If fPSA is to be determined accurately then the whole blood sample must be centrifuged promptly. As the fPSA values in blood samples left at room temperature for 24 h are up to 25% lower than those on immediate assay, and the subsequent f/tPSA 29% lower, then for the optimum use of this test, these samples should also be handled appropriately.

show abstract

Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

The stability of free and bound prostate‐specific antigen

et al. 1999

View full text Add to dashboard Cite

show abstract

“…PSA in serum is stable for 2 4 4 8 h at room temperature, 14 days at 4"C, and 6 months to 12 years at -20°C (42). Repeated freeze-thawing is not recommended because more than one freeze-thaw cycle may either increase or decrease the PSA concentration (43). However, the stability of PSA in the Calibrator and in highly diluted specimens has not been thoroughly studied.…”

Section: Psa Stabilitymentioning

confidence: 99%

Assay for prostate specific antigen (PSA): Problems and possible solutions

1994

Clinical Laboratory Analysis

View full text Add to dashboard Cite

The absolute tissue specificity of prostate specific antigen (PSA) allows the use of PSA test not only for detecting recurrence or metastasis at an early stage after radical prostatectomy but also for screening prostate cancer if combined with digital rectal examination. There is also a need to improve the current PSA test to better differentiate between prostate cancer and benign prostate hyperplasia (BPH). Because of these clinical applications, a much greater demand was placed on PSA test for extra sensitivity, accuracy, and precision even within the normal PSA concentration range. However, the current commercial assay kits for PSA do not provide correct PSA values. Many factors contributing to the problem include the specificity of the anti-PSA antibodies, the composition of the calibrator, the PSA values assigned to the calibrator, the PSA isoform used for anti-PSA antibody preparation, the test design, and the composition of the diluent. Most problems were derived from the failure of realizing earlier that the majority of the PSA exists in serum not as free PSA but as complexes with protease inhibitors. Other problems, such as constantly changing composition of various forms of PSA in serum specimens, and different clearance rates for various forms of PSA make almost impossible to develop an ideal assay for PSA. Therefore, we suggest that test should be designed for measuring PSA-ACT (PSA-alpha 1-antichymotrypsin) complex only. Changing the focus from the measurement of total PSA of various forms to the PSA-ACT complex alone may improve the differentiation between prostate cancer and BPH but may also simplify the selection of anti-PSA antibodies and the preparation of calibrator for the assay.

show abstract

“…Die restlichen 32 (25%) Seren wiesen Werte über 10 ng/ml auf. Einschließlich der hier vorliegenden Arbeit wurde die PSA In-vitTO-Langzeitstabilität in 5 Studien untersucht [5,6,8,13]. Einen Vergleich der Ergebnisse zeigt Tab.…”

Section: Materials Und Methodikunclassified

“…Während Simm u. Mitarb. [13] über signifikante PSA-Erhöhungen bzw. Erniedrigungen bei mehr als einem Auftau-und Einfriervorgang berichten, fanden die beiden anderen Arbeitsgruppen selbst bei bis zu 8 Auftau-und Einfriervorgängen (-20°C und -80°C) innerhalb von 6 Monaten keine signifikanten Veränderungen [6,15].…”

Section: Materials Und Methodikunclassified