What is PSA?

PSA: Prostate Specific Antigen

PSA is an enzyme produced by the prostate which is important for fertility. It is normal to have small amounts of PSA in the blood stream.

Higher levels of PSA in the blood may be an indication of the presence of prostate cancer.

Although PSA is a good test for detecting cancer it is not perfect and just because you have an elevated PSA it does not mean that you have cancer.

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What does it mean if I have a high PSA count? 

There are a number of reasons why your PSA may be up.

The most common reason is that your prostate is enlarged.

Non-cancerous enlargement of the prostate is an almost invariable consequence of aging and while this may cause bladder or voiding problems, it, in itself, is not at all associated with cancer. As the prostate enlarges it produces more PSA and thus different PSA thresholds are employed according to a patient's age.

For example,  while a PSA of 4 might be considered quite normal in a 70 year old it would be abnormally high in a 50 year old.

The generally agreed thresholds are:

  • 40-50y  < 2
  • 50-60y  < 4
  • 60-70y  < 5 

Another non-cancerous cause for an elevation of the PSA is prostatic inflammation or a urine infection. A urine infection in particular can cause the PSA to rise to very high levels - even into the 100s.

Variations in PSA Levels

The PSA level can vary day-to-day and we would always like a confirmation of an elevated PSA prior to proceeding with further investigations, such as prostate biopsy.

The Rise Rate
The rate of rise of the PSA test is also an important factor to consider. If the PSA rises more than 1 unit per year (even though the absolute level may still be within the normal range for age) then this is an indication to look further.

Most men who have a mildly elevated PSA will not have cancer. If the PSA is less than 10 then the risk of cancer is only around 25%. If cancer is detected at these low levels of PSA then it is likely to be at an early stage where curative options are possible. Of course, not all men who have prostate cancer need curative (or indeed any), treatment, and these issues are addressed in the prostate cancer section.