Biomarker Reference · Free PSA
Prostate-Specific Antigen, Free (Free PSA) is a clinical biomarker used in cancer-biomarkers assessment. Free PSA is the unbound fraction of prostate-specific antigen circulating without attachment to protease inhibitors. It is measured in 2 laboratory tests on BiomarkersLabs.com.
Free PSA is the unbound fraction of prostate-specific antigen circulating without attachment to protease inhibitors. The proportion of PSA that is free tends to be lower in prostate cancer and higher in benign prostatic conditions, reflecting differences in the molecular forms produced. The free fraction is reported both as an absolute value and, more usefully, as a percentage of total PSA.
The free-to-total PSA ratio (%free PSA) refines risk assessment in men with a modestly elevated total PSA, typically in the 4–10 ng/mL range with a non-suspicious digital rectal examination. A higher %free PSA favours benign disease and supports a more conservative approach, while a lower %free PSA raises the relative probability of malignancy and may support proceeding to further evaluation.
Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.
2 tests on BiomarkersLabs.com include this biomarker.
Prostate-Specific Antigen, Free reference range in this test: Reported with the free-to-total percentage; higher %free favours benign disease # REVIEWER FLAG: Confirm Access Medical Laboratories reporting format and any %free decision thresholds.
Prostate-Specific Antigen, Free reference range in this test: Reported as an absolute value and used to calculate the percent free PSA; no standalone threshold # REVIEWER FLAG: Free PSA is interpreted via the percent free calculation, not a fixed cut-off — reviewer to confirm reporting against LabCorp's assay.
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