Total Prostate Specific Antigen (tPSA)
, Prostate Specific Antigen, Total (tPSA)
Specimen Collection Criteria
Collect: One 5 mL gold-top SST (minimum whole blood 4 mL)
Minimum serum: 1 mL
Contact Laboratory for acceptability of other tube types.
Physician Office/Drawsite Specimen Preparation
Allow blood to clot for 30 minutes at room temperature (20-25°C or 68-77°F). Then, centrifuge ASAP to separate serum from cells.
Refrigerate (2-8°C or 36-46°F) the centrifuged gold-top tube prior to pick-up by courier. Room temperature is acceptable for maximum of 2 hours.
Preparation for Courier Transport
Transport refrigerated (2-8 °C or 36-46 °F).
Plasma, severely lipemic, or hemolyzed specimens will not be tested.
Once blood has clotted, centrifuge ASAP to separate serum from cells.
If red-top tube (without separator gel) or microtainer is received, specimen must be centrifuged and serum must be removed from cells ASAP.
For more information on this test please see procedures at InsideBeaumont Clinical Pathology, Automated Chemistry
Centrifuged SST tubes and microtainers with separator gel may be stored at room temperature for 2-4 hours. For longer storage, specimen should be refrigerated. DO NOT FREEZE collection tube.
Red-top tubes and microtainers without separator gel may be stored at room temperature for up to 2 hours. For longer storage, serum should be removed from clot/cells and refrigerated with tube capped. DO NOT FREEZE collection tube.
Serum specimens (pour-overs) may be stored at room temperature for 2 hours. For longer storage, sample should be capped and refrigerated for up to one week or frozen.
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Results available within 24 hours after receipt in Chemistry Laboratory.
< or = 2.5 ng/mL
Using a tPSA cut-off value of 4.0 ng/mL, one achieves a sensitivity of 78% and a specificity of 60%. Lowering PSA threshold to 2.5 ng/mL may increase the rate of cancer detection in men younger than 60 years of age with little loss in specificity.
The %complexed PSA (%cPSA) is the most recent of five different approaches being used to improve the ability of PSA to detect early prostate cancer.
Age-Specific Reference Ranges:
The lab has not established age related cut-offs for our tPSA assay.
TPSA Serum value is divided by the prostatic volume determined by transrectal ultrasonography (TRUS). Patients with tPSA values between 4.0-10 ng/mL, negative digital rectal examination (DRE), and tPSA density greater than 0.15 have increased risk of prostate cancer.
A baseline tPSA value is established and the rate of increase of tPSA calculated. An average rate of 0.75 ng/mL/yr increased the specificity of tPSA to differentiate prostate cancer from BPH to 90%.
The %fPSA test order, which included a tPSA, was performed only when the tPSA is between 4 and 10 ng/mL. Our research data suggests Beaumont patients with %fPSA values above 24% had a 1 in 10 chance of having a positive biopsy. % free PSA is now calculated (100-%cPSA).
%Complexed PSA (%cPSA):
"Recent studies suggest: 1) for patients with a tPSA of 2.5-10.0 ng/mL, the %cPSA (>76%) may improve the sensitivity of tPSA for prostate cancer detection and eliminate unnecessary biopsies; 2) for patients with a tPSA of 2.5-4.0 ng/mL, a cPSA cut-off of 2.2 ng/mL results in 92% sensitivity and 42% specificity prostate cancer detection."
PSA is a serine protease (Kalikrein family) produced by epithelial cells of the acini and ducts of prostate gland. Normally, very little PSA is secreted into the blood. Increased PSA levels may be due to increases in glandular size and tissue damage caused by benign prostatic hypertrophy, prostatitits, and/or prostate cancer. The tPSA assay is used to monitor patients with a history of prostate cancer, both as an indicator of tumor recurrence and response to therapy.
The American Cancer Society recommends annual examination with digital rectal examination (DRE) and serum tPSA beginning at age 50 for men with a life expectancy of at least 10 years after detection, Men in a high risk group (African Americans) or those with strong familial predisposition, testing may begin at a younger age.
|Automated Chemistry Laboratory
|Valerie Peterson, MT(ASCP)SC
|| (248) 995-8385
|Elizabeth Sykes, M.D.
|Theresa Erfourth, MT(ASCP)
|Ralph Zade, M.D.
|Kathleen Cousineau, MT(ASCP)
|Beatrice Muglia, M.D.