PSA test
Prostate specific antigen
Granskad av Dr Toni Hazell, MRCGPSenast uppdaterad av Dr Philippa Vincent, MRCGPLast updated 15 dec 2024
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I denna serie:Prostate problemsEnlarged prostateUrinary retentionUrethral strictureChronic prostatitisLower urinary tract symptoms in men
The PSA test (prostate specific antigen) is a blood test which assesses for the likelihood of prostate cancer. It is also used to monitor the treatment for prostatacancer.
The PSA blood level can also be increased in other conditions. Having an increased PSA test result does not therefore mean that prostate cancer is the diagnosis. At the moment there is no national screening programme for prostate cancer in the UK but there are currently studies looking at whether screening would be appropriate for prostate cancer.
The TRANSFORM randomised controlled trial is being planned to start during 2024. This will include a PSA test amongst others in assessing whether a prostate cancer screening programme is possible or appropriate.
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Cross-section diagram of the prostate and nearby organs
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What is a PSA test?
The PSA test (prostate specific antigen) is a blood test that measures the level of prostate specific antigen in the blood. PSA is a protein which is made by the prostate gland. The PSA level in the bloodstream is measured in nanograms per millilitre (ng/mL). PSA is made by normal prostate cells but also by prostate cancer cells.
PSA test preparation
Tillbaka till innehållBefore having a PSA test, it is important not to have:
An active urine infection.
Produced semen during sex or masturbation (ejaculated) in the previous 48 hours.
Exercised heavily in the previous 48 hours.
Had a prostate biopsy in the previous six weeks.
Had an examination of the back passage with a gloved finger (a digital rectal examination) in the previous week.
Had receptive anal intercourse for a period of 48 hours before a PSA test.
Each of these may produce an unnaturally high PSA result, resulting in unnecessary further investigations.
In England, the PSA test may be offered to any man aged 50 and over who requests it as long as they have considered the pros and cons of having the test. The test may be offered to younger men who have a higher risk of prostate cancer.
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The normal range for a PSA test
Tillbaka till innehållThe normal range changes as men age.
PSA Cut-off Values | |
|
|
40-49 | 2.5 micrograms/litre or higher |
50-59 | 3.5 micrograms/litre or higher |
60-69 | 4.5 micrograms/litre or higher |
70-79 | 6.5 micrograms/litre or higher |
There are no age-specific reference limits for men older than 80 years of age. Any referral will depend on local guidelines.
Generally, the higher the level of PSA, the more likely it is to be a sign of cancer.
Benefits and limitations of a PSA test
Tillbaka till innehållBenefits of PSA testing
PSA testing may lead to prostate cancer being detected earlier, before symptoms develop.
Detecting prostate cancer early before symptoms develop may improve the outcome (prognosis) and improve the chance of a complete cure.
Limitations and risks of PSA testing
False negative result: about 15 out of 100 men with a negative PSA test may have prostate cancer.
False positive result: about 75 out of 100 men with a positive PSA test have normal prostate investigations, ie no evidence of cancer.
A false positive PSA test may lead to unnecessary investigations, such as a prostate biopsy, and there may be side-effects from this investigation, such as bleeding or infection. This is less common nowadays as MRI scans are a more common initial investigation which carry lower risks.
A positive result may also lead to unnecessary treatment. Many prostate cancers are slow growing and may not become evident during a man's lifetime. Side-effects of treatment are common and can be serious, such as urinary incontinence and sexual problems.
Current statistics suggest that, in men between the ages of 50 and 66 who are screened for 13 years, annual PSA testing would result in the avoidance of death from prostate cancer of 1.3 per 1000 men.
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Causes of a raised PSA level
Tillbaka till innehållA raised PSA level may be due to a diagnosis prostate cancer but about three out of four men with a raised PSA level will not be found to have prostate cancer.
Other conditions may also cause a raised PSA level, including:
Inability to pass urine, causing an enlarged bladder (acute retention of urine).
Older age.
Transurethral resection of the prostate (TURP) operation. TURP is a prostate operation used if you have benign enlargement of the prostate.
Having a catheter in place to help pass urine.
PSA test results
Tillbaka till innehållIf the PSA level is not raised
Prostate cancer is less likely. A digital rectal examination may also be needed to rule this out.
If the PSA level is slightly raised
Prostate cancer is less likely. A digital rectal examination may also be needed to rule this out. Annual PSA tests might be advised.
If the PSA level is definitely raised
The GP will do an urgent referral to a urologist (a specialist doctor) for further tests for prostate cancer. The specialist will discuss the options for further investigations, which may include a sample taken (a biopsy) of the prostate gland and an MRI scan.
If prostate cancer is found, what are my options?
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Vidare läsning och referenser
- Prostate cancer risk management programme: overview; Public Health England
- Suspected cancer: recognition and referral; NICE guideline (2015 - last updated April 2026)
- Prostate cancer: diagnosis and management; NICE Guidance (2019 - last updated December 2021)
- Prostate cancer; NICE CKS, augusti 2025 (endast tillgång i Storbritannien)
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Artikelhistorik
Informationen på denna sida är skriven och granskad av kvalificerade kliniker.
Next review due: 14 Dec 2027
15 dec 2024 | Senaste versionen
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