Prostate Specific Antigen Test PSA

Authored by , Reviewed by Dr Adrian Bonsall | Last edited

Prostate cancer is a serious condition. The prostate specific antigen (PSA) test is a blood test to see if you might have prostate cancer and to monitor treatment for prostate cancer.

The PSA blood level is also increased in other conditions. So having an increased PSA test result does not mean that you have prostate cancer. Experts disagree on how useful the PSA test is. There is a lot of ongoing research about PSA. At the moment there is no national screening programme for prostate cancer in the UK.

Cross-section diagram of the prostate and nearby organs

Cross-section diagram of the prostate and nearby organs

The prostate gland (just called prostate from now on) is only found in men. It lies just beneath the bladder. It is normally about the size of a chestnut.

The tube which passes urine from the bladder (this is called the urethra) runs through the middle of the prostate. The prostate's main function is to produce fluid which protects and enriches sperm.

The prostate often gets bigger (enlarges) gradually after the age of about 50. By the age of 70, about 8 in 10 men have an enlarged prostate. It is common for older men to have urinary symptoms caused by a non-cancerous (benign) enlargement of the prostate. Some men also develop prostate cancer. See separate leaflet called Prostate Gland Enlargement for more details.

Prostate cancer is a cancer which develops from cells in the prostate gland. It is the most common cancer in men in the UK. Each year, about 40,000 men are diagnosed with prostate cancer in the UK. It affects about 1 in 9 men in the UK at some point in their lives. Most cases develop in men over the age of 65.

Prostate cancer is different to most other cancers because small areas of cancer within the prostate are actually very common, especially in older men. These may not grow or cause any problems for many years (if at all). See separate leaflet called Prostate Cancer for more details.

The PSA test is a blood test that measures the level of PSA in your blood. PSA is made by the prostate gland. The PSA level in your bloodstream is measured in nanograms per millilitre (ng/mL).

When you have a PSA test, you should not 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.

Each of these may produce an unusually high PSA result.

If you decide to have a PSA test, your doctor will give you a digital rectal examination to feel the prostate. This is to find out if the prostate is enlarged or feels abnormal in any way.

Editor's note

March 2018 - Dr Hayley Willacy draws your attention to the newly released Public Health England advice available in the Further reading section below. The guidance helps GPs give clear and balanced information to men who do not have symptoms when they ask about prostate specific antigen testing. The PSA test is available free to any well man aged 50 and over who requests it. GPs should use their clinical judgement to manage men with symptoms and those aged under 50 who are considered to have higher risk for prostate cancer.

The normal range changes as you get older.

PSA Cut-off Values  

Age (years)

PSA Cut-off

40-492.0 nanogram/mL or higher
50-593.0 nanogram/mL or higher
60-694.0 nanogram/mL or higher
70 or older5.0 nanogram/mL or higher
There are no age-specific reference limits for men older than 80 years of age.

The higher the level of prostate specific antigen (PSA), the more likely it is to be a sign of cancer.

The PSA test can also miss cancer. About 15 in every 100 men who have prostate cancer will have had a normal PSA level. A one-off test is not reliable and repeating the test may provide important information.

A raised PSA level may mean you have prostate cancer but about two out of three men with a raised PSA level will not have prostate cancer.

Other conditions may also cause a raised PSA level, including:

If your PSA level is not raised

You are unlikely to have cancer. No immediate further action is needed but you may need further tests to confirm the result.

If your PSA level is slightly raised

You probably do not have cancer. You might need further tests, including more PSA tests.

If your PSA level is definitely raised

Your GP will refer you to see a doctor who is a specialist for you to have further tests to find out if you have prostate cancer. The specialist will discuss with you the options for further investigations, which may include a sample taken (a biopsy) of your prostate gland and an MRI scan.

For information about the treatment options for prostate cancer, see separate leaflet called Prostate Cancer.

Further reading and references

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