December 20, 2020

What is PSA?

PSA stands for Prostatic Specific Antigen, a protein that is produced by the prostate and released into the blood. The prostate is a gland of the male reproductive system that is about the size of a walnut. It secretes fluid that helps sperms swim during ejaculation. Cancer in the prostate gland is the most commonly diagnosed cancer in the UK.

Across the UK, more than 47,500 men are diagnosed with prostate cancer every year and every 45 minutes one man dies from prostate cancer. 1 in 8 men will be diagnosed with prostate cancer in their lifetime.

Healthy men usually have a low level of PSA in the blood that can be detected by a PSA test. Men with a fast-growing prostate cancer can have very high levels of PSA in the blood. However, increased age, prostate size, infection or inflammation, as well as trauma can all cause the level of PSA in the blood to rise.

Why is this analysis important?

A PSA test is usually performed as a part of a general health check with the aim to find early signs of prostate cancer before symptoms of the cancer appear. Finding cancer early makes it easier to treat and the chances of full recovery is higher.

It is recommended to perform the PSA test in men that are at higher risk for prostate cancer, which includes men:

  • Aged 50 or older, as prostate cancer risk increases with age

  • With a close relative, for example brother or father, who has had prostate cancer

  • Of black ethnic origin.

However, PSA is not a perfect test for prostate cancer.

Many men with raised PSA levels don’t have prostate cancer. And some men with a normal PSA level do have prostate cancer. The following advantages and disadvantages of the PSA test should be noted.


  • It may reassure you if the test result is normal

  • It can find early signs of cancer, meaning you can get treated early

  • PSA testing may reduce your risk of dying if you do have cancer


  • It can miss cancer and provide false reassurance

  • It may lead to unnecessary worry and medical tests when there's no cancer,

  • It cannot tell the difference between slow-growing and fast-growing cancers,

  • It may make you worry by finding a slow-growing cancer that may never cause any problems.


The reference range for PSA levels in the blood can be different depending on your age. Doctors usually also take into account a number of factors when evaluating PSA values.

High PSA levels in the blood may be associated with:

  • Prostate cancer

  • Enlarged prostate

  • Infection or inflammation in the prostate

  • Recent sexual activity

  • Vigorous exercise

Low PSA levels in the blood are normal.

Other Considerations

In order to correctly measure your PSA level in the blood, you should not have:

  • ejaculated in the past 48 hours

  • exercised heavily in the past 48 hours

  • a urinary infection

  • had a prostate biopsy in the past 6 weeks

Medication against benign prostate hyperplasia (BPH), also called prostate enlargement, can affect your PSA levels. Assessment of prostate cancer risk based on PSA level for men taking medications such as Finasteride (Proscar® or Propecia®) or Dutasteride (Avodart®) should be performed by the treating physician.

Tests that include this marker


Prostate specific antigen testing: advice for well men aged 50 and over. Public Health England. Updated 20 January 2020.

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