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Free Prostate-Specific Antigen (Free PSA)

Published: July 27, 2026Updated: August 25, 2026

Free PSA measures the unbound form of PSA in the blood, aiding in the differentiation between benign prostate conditions and prostate cancer.

Quick summary

Free PSA helps distinguish between benign prostate conditions and prostate cancer.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
ng/mL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche fPSA, Abbott fPSA, Siemens fPSA
interpretation: {"text":"Suggests a higher risk of prostate cancer. Further diagnostic tests are recommended.","label":"Low Free PSA (<0.9 ng/mL)"}; {"text":"Indicates a lower risk of prostate cancer and may suggest a benign condition.","label":"High Free PSA (≥0.9 ng/mL)"}

Free Prostate-Specific Antigen (Free PSA) is a biomarker used to assess the risk of prostate cancer. It represents the unbound fraction of PSA in the bloodstream.

Unlike total PSA, which includes both bound and unbound forms, free PSA levels can help differentiate between prostate cancer and benign prostatic hyperplasia (BPH).

A lower free PSA percentage may indicate a higher risk of prostate cancer, while a higher percentage suggests a benign condition.

Frequently asked questions

What is the normal range for Free PSA?
The reference range for Free PSA is typically 0–0.9 ng/mL.
How is Free PSA different from Total PSA?
Free PSA measures only the unbound form, while Total PSA includes both bound and unbound forms. Free PSA is used to improve the specificity of prostate cancer diagnosis.
  1. 1
    American Cancer Society: Prostate Cancer Early DetectionSource
  2. 2
    National Cancer Institute: Prostate-Specific Antigen (PSA) TestSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy