PSA test

This is a blood test that measures the total amount of prostate specific antigen (PSA) in your blood. PSA is a protein produced by normal cells in the prostate and also by prostate cancer cells. It is normal for all men to have a small amount of PSA in their blood. A raised PSA level may show that you have a problem with your prostate, but not necessarily prostate cancer.

All men are entitled to have a PSA test as long as they have first talked through the pros and cons with their GP. You can have a PSA test at your GP surgery.

A raised PSA level can show that there might be a problem with your prostate. To find out what this problem may be, your GP will ask you about any symptoms and can do a number of other tests.

A raised PSA level can be a sign of prostate cancer. But some men with a normal PSA level can also have prostate cancer.

The amount of PSA in your blood is measured in nanograms (a billionth of a gram) per millilitre of blood (ng/ml).

Contents

What can affect my PSA level?

  • Age
  • Urine infection
    Your GP will test for this and treat any infection. They will give you the PSA test after treatment.
  • An enlarged prostate
  • Prostatitis
  • Prostate cancer
  • Vigorous exercise
    You might be asked to avoid vigorous exercise for 48 hours before the test as it may raise your PSA level.
  • Ejaculation
    You may be asked to avoid sexual activity for 48 hours before the PSA test.
  • Biopsy
    Prostate biopsy in the six weeks before a PSA test could affect the result.
  • A catheter or investigations or operations on your bladder or prostate
    You may need to wait up to six weeks before having a PSA test.
  • Medicines
    Tell your GP if you are taking any prescription or over-the-counter medicines.

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What do the results mean?

A PSA test alone cannot diagnose prostate cancer. PSA naturally rises as men get older and the prostate gland gets bigger. A high PSA level for your age can be a sign of prostate cancer, but it can be caused by other things. The following figures are a very rough guide to 'normal' PSA levels, depending on your age:

  • up to 3 ng/ml for men in their 50s
  • up to 4 ng/ml for men in their 60s
  • up to 5 ng/ml for men in their 70s and over

A very high PSA level (in the hundreds or thousands) normally means that a man has prostate cancer. If your PSA level is only slightly raised, then your doctor would do other tests to find out if there is a problem.

Your GP will consider your PSA level together with your DRE result, any risk factors or other health problems and any previous biopsy results before discussing the next step with you.

If your test results are within the normal range you may not need any further tests or your GP may advise you to have another PSA test in the near future.

If they think that you may have a prostate problem then they might refer you to the hospital. You can also ask your GP to refer you to a hospital specialist.

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What are the advantages and disadvantages of the test?

Advantages

  • It may help pick up a more aggressive cancer at an early stage when treatment may prevent the cancer from becoming more advanced.
  • Regular PSA tests could be helpful for men who have a higher risk of developing prostate cancer, but we need more evidence about the best way of doing this.

Disadvantages

  • Around two thirds of men with a raised PSA do not have prostate cancer.
  • It will not pick up all prostate cancers. Some men with prostate cancer have a normal PSA level.
  • It cannot tell you whether a prostate cancer is likely to be fast or slow growing (high or low risk). A slow growing cancer may not cause any symptoms or shorten your life.
  • If your PSA is raised, you may need a biopsy which some men find uncomfortable and has some risks.
  • Treatment for prostate cancer may cause significant side effects which can affect your daily life.

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Should I have a PSA test?

To help you decide, ask yourself the following questions.

  • Are you more at risk of prostate cancer?
  • If the result of your PSA test was normal, would this reassure you?
  • If your PSA was high, what would you do?
  • If you went on to be diagnosed with slow growing prostate cancer that might not cause you any problems in your lifetime, would you want to have treatment that may cause side effects?

Speak to your GP about any concerns before making a decision or contact the Specialist Nurses on our helpline.

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Should I have regular PSA tests?

After some men have had their first PSA test, they may choose to have regular tests, particularly if they are more at risk of prostate cancer. This might be a good way to spot any changes in your PSA levels. At the moment there is no research to show how often men should have tests, but this could be every one or two years. You could discuss this further with your GP or call our Specialist Nurses on our confidential helpline.

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Why is there no screening programme?

Screening programmes aim to spot early signs of cancer in people who do not have any symptoms. There is no screening programme for prostate cancer. One reason for this is that the PSA test is not reliable enough to be used as part of a screening programme.

Some studies show that screening using the PSA test could reduce the number of deaths from fast growing prostate cancer but it could also increase the number of men having unnecessary treatment for slow growing prostate cancer.

In most cases prostate cancer is slow growing and may not cause any problems in a man's lifetime. However, some men will have fast growing cancer that needs treatment to delay or prevent it spreading outside of the prostate gland.

Treatment can cause significant side effects so screening could lead to many men having worse side effects from treatment than they would have had from the cancer.

If you are concerned about prostate cancer you can talk to your GP about your individual risk and talk through the advantages and disadvantages of the PSA test. If you then decide that you want a PSA test, you can ask your GP for one.

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Questions to ask your GP

  • What are the pros and cons of having a PSA test?
  • Do I have an increased risk of developing prostate cancer?
  • How long will I have to wait for the results?
  • If I have a PSA test and the result is normal, will I need to have regular tests in the future?
  • What is my PSA level?
  • Do I need a DRE?

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References

You can find a full list of references used to produce this page on our references page.

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Understanding the PSA test

Understanding the PSA test: A guide for men concerned about prostate cancer

This booklet is for men who are considering having a PSA test or want to know more about PSA (Prostate Specific Antigen). Patient Information Award Winner for Men's Health (2009) at the BMA Medical Book awards.