Free PSA
Free PSA is the portion of prostate-specific antigen in the blood that is not bound to plasma proteins. Together with total PSA it forms the %-free PSA ratio, which helps distinguish benign prostate enlargement from prostate cancer when total PSA is in the grey zone (roughly 4–10 ng/mL).
Why it matters: Free PSA alone is rarely actioned; its clinical value comes from the ratio free/total. A higher %-free generally suggests benign prostatic hyperplasia, a lower %-free raises concern for prostate cancer. Interpretation is highly context-dependent and requires specialist input.
May increase with:
May decrease with:
What is Free PSA?
Free PSA is the portion of prostate-specific antigen in the blood that is not bound to plasma proteins. Together with total PSA it forms the %-free PSA ratio, which helps distinguish benign prostate enlargement from prostate cancer when total PSA is in the grey zone (roughly 4–10 ng/mL).
What might a high or low Free PSA mean?
Free PSA alone is rarely actioned; its clinical value comes from the ratio free/total. A higher %-free generally suggests benign prostatic hyperplasia, a lower %-free raises concern for prostate cancer. Interpretation is highly context-dependent and requires specialist input.
What can affect Free PSA?
It may be higher with: Benign prostatic hyperplasia, Prostatitis. It may be lower with: Prostate cancer (relative), Recent prostate manipulation (DRE, biopsy, catheterization) transiently.