Understanding PSA test results

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The PSA test measures the level of PSA (prostate specific antigen) in your blood. It can be used: 

• To help diagnose prostate cancer. 
• To help diagnose other prostate problems.
• To show how your cancer is responding to treatment − PSA usually falls once you start treatment.

What is PSA?

PSA is a protein made by your prostate gland. It is measured in nanograms per millilitre of blood (ng/ml). PSA levels can range from less than 1ng/ml up to 100 ng/ml and beyond.

What are normal PSA levels? 

There is no such thing as a completely 'normal' PSA level. For example, PSA levels often rise as you get older. There are also other things that can affect your PSA level. But to see if there might be a problem with your prostate, doctors will check your PSA level against what is usual for men your age:

• Under 50 years of age: Up to 2ng/ml
• 50-59: Up to 3ng/ml
• 60-69: Up to 4ng/ml
• 70+: Up to 5 ng/ml

Does a high PSA mean I have cancer?

No. There are other reasons your PSA can be raised. A PSA test alone can’t diagnose cancer. but doctors will use the age-range levels to decide if you might need further tests.

What are some of the reasons PSA can be raised?

• Recent urinary tract infection.
• Prostatitis (infection in the prostate).
• An enlarged prostate, which is common as men get older.
• Prostate cancer.

Other things that can affect PSA levels:

• A recent operation on your prostate gland.
• A recent prostate biopsy.
• Ejaculation within the previous 48 hours.
• Tests on your bladder or prostate gland, especially a tube (catheter) placed there.

Some medications can such as finasteride (Proscar ®) and dutasteride (Avodart ®), which are taken for an enlarged prostate, can make the PSA appear lower than it is. Doctors usually allow for this by doubling your PSA result if you are on these medications. 

What will happen if my PSA is raised?

• If your PSA is a little raised and you have no other abnormal results (such as from the rectal exam), your GP will usually advise you to have your PSA done again after about 6 - 12 weeks.
• If your PSA is raised a second time or it’s a little raised but your prostate gland feels abnormal your doctor will usually advise you to see a urologist to discuss having a prostate biopsy.  
• If your PSA is very high (such as over 100), usually your doctor will refer you to a urologist straight away.

What happens if my PSA is in the normal range?

• If your PSA is normal and your prostate gland feels normal, your GP will tell you if and when you need to think about having your PSA test repeated. 
• If your PSA is normal but your prostate gland feels abnormal, your GP will refer you to a urologist.
• If you have a normal PSA but you’re troubled by urinary symptoms, you may still be referred to a urologist to help improve your symptoms.

Types of PSA test

Free/total PSA

This test is a different way of measuring the PSA in the blood. It is useful for men who have a PSA between 4 and 10ng/ml and a normal DRE examination.

The PSA is carried in the blood stream in two different ways: ‘free’ PSA, which is not bound to blood proteins, and PSA that can bind to blood proteins.

The percentage of free PSA tends to be lower in men who may have prostate cancer. Results from this type of test can be useful in helping the urologist to decide how to treat men with a normal biopsy result. It is important to remember that other factors, like the size of the prostate, may influence the measurement.

The doctor will take this into consideration too when deciding the next step.

PSA velocity

This is a measure of how fast the PSA level rises over time. Normally the PSA rises very slowly as you get older. If the PSA level rises by 0.5ng/ml (per year) in a younger man or 0.75ng/ml (per year) in a man over 60 years of age it may increase the suspicion of prostate cancer.

PCA3 urine test 

This test checks urine for the presence of a gene secreted by the prostate cells which is in higher quantities in the presence of prostate cancer. The test is done after the prostate gland has been massaged and may be used to decide if a repeat biopsy is necessary. A PCA3 test cannot say for certain if you have prostate cancer, but it can show how likely it is.