Free PSA blood test
Percent free prostate-specific antigen
In short
A typical adult free PSA result is over 25 % (percent of total PSA). A percent below the range goes with a somewhat higher chance of prostate cancer. It cannot confirm or rule out cancer; doctors weigh it with total PSA, age and a prostate exam. Always read your result against the range printed on your own report.
The share of PSA floating free in the blood, as a percent.
PSA travels in the blood either free or attached to other proteins. This test is mostly used when total PSA is a little high, often between 4 and 10. A lower percent goes with a somewhat higher chance of prostate cancer, a higher one with an enlarged prostate.
Is my Free PSA high or low?
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Typical range
| For | Range | Unit |
|---|---|---|
| Adults · percent of total PSA | over 25 | % |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your Free PSA is low
A percent below the range goes with a somewhat higher chance of prostate cancer. It cannot confirm or rule out cancer; doctors weigh it with total PSA, age and a prostate exam.
Common reasons
- Natural variation: most men with results of 10 to 25% do not have cancer
- A smaller prostate, which tends to give a lower percent
- A sample left too long before testing, as free PSA breaks down
- Less often: prostate cancer, especially when the result is below 10%
What can throw it off
Free PSA breaks down if the sample sits too long before testing, which can make the percent look lower.
Questions to take to your appointment
- 1How does this change my chances, given my total PSA and age?
- 2Does this change whether I need a scan or a biopsy?
- 3Was my sample tested quickly enough for this test?
Read together with
Doctors rarely read Free PSA alone. These usually sit next to it.
Quick answers
What is the free PSA blood test?
Free PSA (Percent free prostate-specific antigen): The share of PSA floating free in the blood, as a percent. PSA travels in the blood either free or attached to other proteins. This test is mostly used when total PSA is a little high, often between 4 and 10. A lower percent goes with a somewhat higher chance of prostate cancer, a higher one with an enlarged prostate.
What is a normal free PSA level?
For most adults, free PSA is typically over 25 % (percent of total PSA). Labs differ a little, so the range printed next to your result is the one to go by.
What does a low free PSA mean?
A percent below the range goes with a somewhat higher chance of prostate cancer. It cannot confirm or rule out cancer; doctors weigh it with total PSA, age and a prostate exam. Common reasons include natural variation: most men with results of 10 to 25% do not have cancer; a smaller prostate, which tends to give a lower percent; a sample left too long before testing, as free PSA breaks down; and less often: prostate cancer, especially when the result is below 10%.
What can affect my free PSA result?
Free PSA breaks down if the sample sits too long before testing, which can make the percent look lower.
What should I ask my doctor about my free PSA?
Questions worth taking to the appointment: How does this change my chances, given my total PSA and age? Does this change whether I need a scan or a biopsy? Was my sample tested quickly enough for this test?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
We also make Vita: Health Coach, an app for those parts. It reads your whole report with your medicines and history in mind, answers follow-up questions in plain words, and keeps your reports in one place — for you and for the people you look after.
Vita: Health Coach on the App StoreSources
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