% Free PSA
Free PSA as a percentage of total PSA, used to refine prostate cancer risk estimates.
| Typical reference range | above 25 % |
Ranges vary by laboratory, method, age and sex: always use the range printed on your own report. Why labs differ.
What it measures
Percent free PSA equals free PSA divided by total PSA, times 100.
Why it matters
In men with total PSA between about 4 and 10 ng/mL, a higher percentage free PSA suggests a benign cause, while a lower percentage increases the likelihood of cancer and can help guide biopsy decisions.
What a high result can mean
Values above ~25% are associated with a lower probability of prostate cancer and more often reflect benign enlargement.
What a low result can mean
Values below ~10% are associated with a substantially higher probability of prostate cancer.
What affects the result
Most useful when total PSA is in the 4-10 ng/mL range and the prostate exam is normal. Prostate size and 5-alpha reductase inhibitors affect interpretation.
Unit
Usually reported in %.
Also called on lab reports
PSA, % Free, Percent Free PSA, Free PSA %, PSA, Free, Percent, % PSA, Free, PSA Free/Total Ratio
Related tests: Prostate
This page is educational and does not replace advice from a healthcare professional.