PSA test

Cross-section diagram of the prostate and nearby organs

What is a PSA test?

The PSA test (prostate specific antigen) 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.

• Had receptive anal intercourse for a period of 48 hours before a PSA test. This is an essential requirement for gay, bisexual, and other men who have sex with men.

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 gland. This is to find out if the prostate gland is enlarged or feels abnormal in any way.

In England, 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.

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What is a normal result?

The normal range changes as you get older.

There are no age-specific reference limits for men older than 80 years of age. Whether you are referred will depend on your discussion with your doctor.

The higher the level of PSA, the more likely it is to be a sign of cancer.

What are the benefits and limitations of a PSA test?

Benefits 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 outcome (prognosis) and improve the chance of 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 a normal prostate biopsy (ie no evidence of cancer).

• Therefore 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.

• A positive result may also lead to unnecessary treatment. Many prostate cancers are slow growing and may not become evident during your lifetime. Side-effects of treatment are common and can be serious, such as urinary incontinence and sexual problems.

What causes a raised PSA level?

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:

• Inability to pass urine, causing an enlarged bladder (acute retention of urine).

• Enlargement of the prostate that is non-cancerous (benign).

• Older age.

• Urine infection.

• Acute prostatitis.

• Transurethral resection of the prostate (TURP) operation. TURP is a prostate operation used if you have benign enlargement of the prostate.

• If you have a tube (catheter) to help pass urine

What happens after a PSA test?

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.

If prostate cancer is found, what are my options?