Free PSA test (fPSA) explained

PSA (prostate-specific antigen) is a protein made by the cells of the prostate gland. In the blood it exists in two forms: the larger part is bound to plasma proteins, and a smaller part is free, unbound — free PSA, or fPSA. According to MedlinePlus, for the PSA test there is “no one specific normal or abnormal level” — the result depends on age, prostate size and other factors. Free PSA is most often measured together with total PSA, so that the free PSA ratio (its percentage of total PSA) can be calculated. This helps the doctor judge whether it is worth sending you for further testing — a biopsy, for example — especially when total PSA falls into the unclear zone. The test is done from a venous blood sample. According to MedlinePlus, the lower the proportion of free PSA in total PSA, the more likely it is that prostate cancer is present, which is why the result is always interpreted by a doctor together with total PSA and other information.

• When total PSA is in an unclear (“grey”) zone and the doctor is considering whether further diagnostic tests are needed
• To assess the state of the prostate alongside other prostate tests
• To monitor the prostate after treatment or procedures
• When a physical examination finds changes in the prostate
• When prostate cancer is suspected and more information is needed alongside total PSA

• According to the NHS, for 48 hours before the test it is worth avoiding anal sex, ejaculation, vigorous exercise and cycling
• If you have had a urinary tract infection, the NHS says to wait 4–6 weeks after the infection has cleared before having the test
• Tell your doctor about every medicine you take — some can artificially lower the PSA result (MedlinePlus)

A raised result

Total PSA can be raised for reasons other than prostate cancer. According to MedlinePlus, a raised PSA can be caused by benign enlargement of the prostate, inflammation of the prostate, a urinary tract infection and other prostate conditions, and some medicines can also affect the result. With free PSA the direction is the opposite: the lower its proportion of total PSA, the more likely cancer is (MedlinePlus). The cause is assessed by a doctor together with other tests.

• Benign enlargement of the prostate (BPH)
• Prostatitis — inflammation of the prostate
• Urinary tract infection
• Certain medicines (MedlinePlus)
• Recent ejaculation or cycling (NHS)

What the doctor looks at next

• Whether there was a urinary tract infection, a recent procedure or sexual intercourse at the time of the test or before it — these can temporarily raise the result
• The ratio of free to total PSA (the free PSA percentage) — it helps the doctor judge whether further tests are needed
• A prostate examination and other tests, if the doctor recommends them
• When to repeat the test, so that the change over time can be seen

The fPSA test can be done at most laboratories in Lithuania, either with a doctor's referral or on your own. For the specific price and conditions, contact the laboratory you choose.

Related tests

• PSA (total)
• CA 125
• HE4
• CEA
• ROMA index