Prostate specific antigen (PSA), total
PSA is a single chain chymotrypsin-like serine protease of approximately 30 kDa. It is produced by the epithelial cells lining the acini and ducts of the prostate gland, and plays a role in the liquefaction of seminal fluid. Low levels of PSA are found in the blood as a result of leakage from the prostate gland. Increasing levels of serum PSA are associated with prostatic pathology, including prostatitis, benign prostatic hyperplasia (BPH) and cancer of the prostate. Urinary retention, transurethral resection of the prostate (TURP), prostate biopsy, prostate massage and ejaculation may also give rise to increases is serum PSA levels. In the sera PSA is mostly bound to either α-2 macroglobulin (AMG) or α-1 antichymotrypsin (ACT). The total PSA test measures free PSA and that bound to ACT with approximate equimolarity. PSA bound to AMG is not detected by the total PSA test.
The proportion of protein-bound PSA increases in malignancy compared with that observed in BPH or prostatitis. Hence, separate measurement of free PSA and calculation of the ratio (the %fPSA test) is helpful in distinguishing men with prostate cancer from men with BPH (see percentage free PSA test for more details). Although PSA levels increase in age and there have been arguments to revise the current cut-off of ≥4.0 µg/L, no overall clinical benefit for raising or lowering has been clearly demonstrated. Repeat testing to ascertain the rate of increase in total PSA is a helpful approach for increasing specificity of total PSA for distinguishing prostate cancer.
Diagnosis: due to the wide inter- and intra-individual variation in serum PSA levels in healthy men and overlap with PSA levels observed in disease, total PSA measurement should be used in combination with digital rectal examination (DRE) in men suspected of having prostate cancer. Percentage free PSA measurement and repeat testing can also be used to enhance specificity.
Prognosis and staging: total PSA levels correlate stage of disease and can be used for determining prognosis
Treatment monitoring: PSA is useful in monitoring response to treatment.
Surveillance: PSA is used for detection of early recurrence following prostatectomy.
| Age (years) | Total PSA threshold (µg/L) |
| < 40 | Use clinical judgement |
| 40-49 | > 2.5 |
| 50-59 | > 3.5 |
| 60-69 | > 4.5 |
| 70-79 | > 6.5 |
| > 79 | Use clinical judgement |
4 days
Please note: This test is now also available at Hillingdon, but UKAS accreditation for this site is pending.
Record last updated
August 26, 2025
Sample Container
5ml SST Vacutainers (Gold / Yellow top)
Sample Container
24hr Urine Bottle (Plain label)
Sample Container
6ml Plain Vacutainers (Red top)
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Test Results
Yes, we have a Pathology User Guide
Yes. Please email your request to Imperial.nwlpcustomerservice@nhs.net
Results are communicated to clinical staff and are normally not communicated direct to patients either on telephone requests or in written report. If you need to contact us please click here to view the contact details page
Please contact the Customer Service Team Monday to Friday from 8:30am – 6:00pm on 0203 313 5353. Alternatively, see the Pathology User Guide for how to contact the relevant department. If advice is not urgent you can also email your query to Imperial.nwlpcustomerservice@nhs.net
Additional tests may be added by discussion with the relevant laboratory. The time limit for adding additional tests to a sample already received in the laboratory will depend on the type of sample and the department it was sent to.
Information on the repertoire of tests performed by pathology, including reference ranges, turnaround times and specimen requirements, can be found in the test directory.
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Imperial College Healthcare Trust Phlebotomy services
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NWLP operates UKAS accredited medical laboratories as per the references below. The current scope of accreditation for all NWLP’s laboratories can be found on the UKAS website.
UKAS accredited medical laboratory/medical diagnostic service:
- Clinical Biochemistry No. 8673
- Haematology and Blood Transfusion No. 8674
- Infection & Immunity Sciences (Including Immunology, Virology, Microbiology and Histocompatibility and Immunogenetics ) No. 8659
- Cellular Pathology (Including Histopathology, Cytology and Molecular Pathology) No. 9615
If you require copies of our certificate of accreditation and associated documentation please contact Imperial.nwlpcustomerservice@nhs.net.
UKAS requires the laboratories to be accredited for a particular repertoire/scope (ISO15189), any changes or additions to repertoire require assessment by UKAS (extension to scope).
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Home testing
INSTRUCTION SHEET FOR BLOOD SAMPLE COLLECTION
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Our accreditations
Upholding excellence in diagnostic standards
Our laboratories are accredited by the UK Accreditation Service (UKAS) against the international standard ISO15189:2022. UKAS is the accreditation body for the UK that assesses medical laboratories.
Find out more about our accreditations on the UKAS website.
UKAS website