PSA Free and Total Test
The PSA Free and Total test measures total prostate-specific antigen and its free fraction, allowing calculation of the free-to-total ratio (%free PSA). The ratio refines prostate cancer risk assessment in men with a modestly elevated total PSA, typically 4–10 ng/mL with a non-suspicious examination, where a higher %free PSA favours benign disease and a lower %free PSA raises the relative…
2
Biomarkers
Blood (serum)
Sample
2–4 business days
Turnaround
No
Fasting
What is the Free & Total PSA test?
The PSA Free and Total Test measures both total prostate-specific antigen and its free fraction, allowing calculation of the free-to-total ratio (%free PSA). Pairing the two refines the interpretation of a raised total PSA, where the percentage of free PSA helps distinguish benign prostatic conditions from clinically significant prostate cancer. In the diagnostic landscape, total PSA alone is sensitive but not specific, and many elevations reflect benign prostatic hyperplasia or prostatitis rather than malignancy. The free-to-total ratio adds discriminatory value precisely in the diagnostic grey zone — most usefully a total PSA in the 4–10 ng/mL range with a non-suspicious examination — where it can reduce unnecessary biopsy. This combined test is therefore ordered when a man's total PSA is modestly elevated and the practitioner wishes to better characterise risk before deciding on imaging, biopsy, or active surveillance. Decisions remain shared and individualised, weighing the recognised benefits and harms of PSA-based assessment.
What does the Free & Total PSA test measure?
Prostate-specific antigen is a serine protease (kallikrein-3) produced by prostatic epithelial cells and secreted into seminal fluid, where it liquefies the ejaculate. Small amounts enter the circulation, where it exists as a free fraction and as complexed forms bound to protease inhibitors such as alpha-1-antichymotrypsin. Total PSA represents the sum of free and complexed PSA. Serum PSA rises with prostatic volume, inflammation, and malignancy, and has a serum half-life of roughly 2–3 days.
Total PSA is the principal serum marker for prostate cancer screening, detection, and monitoring, and also rises in benign prostatic hyperplasia and prostatitis. It lacks specificity for malignancy, particularly in the diagnostic grey zone of 4–10 ng/mL, where the free-to-total ratio improves discrimination. It is used for risk assessment before biopsy, treatment monitoring, and surveillance after definitive therapy.
Free PSA is the unbound fraction of prostate-specific antigen circulating without attachment to protease inhibitors. The proportion of PSA that is free tends to be lower in prostate cancer and higher in benign prostatic conditions, reflecting differences in the molecular forms produced. The free fraction is reported both as an absolute value and, more usefully, as a percentage of total PSA.
The free-to-total PSA ratio (%free PSA) refines risk assessment in men with a modestly elevated total PSA, typically in the 4–10 ng/mL range with a non-suspicious digital rectal examination. A higher %free PSA favours benign disease and supports a more conservative approach, while a lower %free PSA raises the relative probability of malignancy and may support proceeding to further evaluation.
Why is the Free & Total PSA test ordered?
- Risk refinement in men with a modestly elevated total PSA (commonly 4–10 ng/mL) and a non-suspicious digital rectal examination, to inform biopsy decisions
- Evaluation of men where benign prostatic hyperplasia is the likely cause of a raised PSA but malignancy needs to be weighed
- Shared decision-making for prostate cancer risk assessment in men considering whether to proceed to further investigation
- Monitoring of men on active surveillance for low-risk prostate findings, where serial PSA and %free PSA inform trends
- Assessment of persistently elevated PSA after treatment of prostatitis, once inflammation has settled
- Investigation of a borderline PSA in men with a family history of prostate cancer, to support individualised risk discussion
- Follow-up of an isolated PSA elevation where the free fraction may avoid an unnecessary invasive procedure
Sample collection and turnaround
Sample type
Blood (serum)
Fasting required
No
Collection method
Venipuncture at patient service centre
Turnaround
2–4 business days
Collection notes
Advise 48 hours of abstinence from ejaculation before collection. Draw before, or with appropriate delay after, digital rectal examination, prostate biopsy, or catheterisation. Defer testing until any prostatitis or urinary tract infection has resolved. Free PSA is labile — separate serum promptly and store appropriately to preserve a reliable free-to-total ratio. # REVIEWER FLAG: Confirm Access Medical Laboratories free PSA stability and handling requirements before publication.
Specimen requirements
Minimum 1.0 mL serum. Separate serum from cells promptly; measure free and total PSA on the same specimen.
What can affect Free & Total PSA results?
Ejaculation can transiently raise total PSA. Abstinence for 48 hours before collection is commonly advised to avoid spurious elevation.
Mechanical manipulation of the prostate releases PSA into the circulation. Samples should be drawn before, or with appropriate delay after, examination or instrumentation.
Prostatic inflammation increases PSA release, sometimes markedly. Testing should be deferred until infection or inflammation has resolved to avoid misclassification.
These agents roughly halve total PSA over months of use, so measured values must be doubled for interpretation in treated men. # REVIEWER FLAG: Confirm the platform's preferred correction guidance and duration assumptions.
Free PSA is less stable than total PSA and degrades with delayed processing or inadequate cooling, falsely lowering the %free ratio. Prompt separation and appropriate storage are essential for a reliable ratio.
Increasing prostatic volume raises total PSA independent of malignancy, which is part of why the free fraction aids discrimination in this setting.
What do Free & Total PSA results mean?
Elevated
An elevated total PSA raises the possibility of prostate cancer but is non-specific and also occurs with benign hyperplasia and prostatitis. In the 4–10 ng/mL grey zone, a low %free PSA increases the relative probability of clinically significant cancer and supports further evaluation, while a markedly elevated total PSA warrants assessment regardless of the ratio.
Normal
A total PSA within the age-specific range, particularly with a high %free PSA, favours benign disease and supports a conservative, surveillance-based approach. Normal results do not entirely exclude cancer, so interpretation incorporates examination findings, trend over time, and individual risk.
Reduced
A low total PSA is generally reassuring for malignancy risk. In men taking 5-alpha-reductase inhibitors, apparently low values must be doubled to approximate the untreated level before interpretation.
Note: PSA-based assessment carries recognised trade-offs between detecting clinically significant cancer and overdiagnosis of indolent disease, and decisions should be shared and individualised. The free-to-total ratio is informative chiefly within the 4–10 ng/mL range with a non-suspicious examination, and depends on reliable free PSA measurement, which is sensitive to specimen handling. Both fractions should be measured on the same sample using the same assay.
Frequently asked questions
Total PSA is the sum of free and complexed prostate-specific antigen, while free PSA is the unbound fraction. The free-to-total ratio refines risk because a lower percentage of free PSA is associated with a higher relative probability of prostate cancer.
How to access the Free & Total PSA test
The Free & Total PSA reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.
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Published: June 3, 2026
Last reviewed: June 3, 2026
- Catalona WJ, et al. Use of the percentage of free prostate-specific antigen to enhance differentiation of prostate cancer from benign prostatic disease. JAMA. (1998)
- US Preventive Services Task Force. Screening for Prostate Cancer: US Preventive Services Task Force Recommendation Statement. JAMA. (2018)
- Carter HB, et al. Early Detection of Prostate Cancer: AUA Guideline. J Urol. (2013)
- Lilja H, Ulmert D, Vickers AJ. Prostate-specific antigen and prostate cancer: prediction, detection and monitoring. Nat Rev Cancer. (2008)
This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.