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Prostate-Specific Antigen Free

Cancer screening Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Cancer screening

Overview

Free Prostate-Specific Antigen (free PSA or fPSA) is the fraction of PSA circulating in blood that is not bound to plasma proteins. The test measures the unbound PSA level and is interpreted together with total PSA to help distinguish benign prostate conditions (like benign prostatic hyperplasia or prostatitis) from prostate cancer. It is used when total PSA is borderline or mildly elevated to improve diagnostic specificity. Symptoms prompting testing include urinary frequency, weak stream, nocturia, pelvic or perineal pain, or asymptomatic elevation on screening. Results vary with age (PSA rises with advancing age), prostate volume, recent prostate manipulation, inflammation, ejaculation, and are relevant for males only.

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Test Preparation

Do not give sample within 7 days of Digital Rectal Examination (DRE) or Rectal Prostatic Ultrasonography
It is advisable to avoid sexual intercourse, ejaculation, and vigorous exercise for up to 48 hours before sample collection
Prostate biopsy causes a substantial elevation of the PSA levels
Talk to your doctor about the appropriate timing of the test

Why Do I Need This Test

Profile: Cancer screening - Symptoms: Lower urinary tract symptoms, unexplained rise in total PSA, abnormal digital rectal exam - Diagnoses/monitoring: Helps differentiate benign prostatic conditions from prostate cancer and aids biopsy decision-making - Reasons for abnormal levels: Prostate cancer, BPH, prostatitis, recent ejaculation or prostate instrumentation - Biological meaning: Low percent free PSA (relative increase in bound PSA) raises suspicion for cancer; higher percent free PSA favors benign disease - Lifestyle/factors: Recent ejaculation, bicycle riding, urinary retention, recent catheterization or prostate exam can alter levels - Family history: A first-degree relative with prostate cancer increases need for testing and closer interpretation

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Understanding Test Results

A free-to-total PSA ratio ≥25% generally indicates a lower probability of prostate cancer and suggests benign causes (e.g., BPH or prostatitis).
A ratio between ~10–25% is equivocal the risk of cancer is intermediate and further evaluation (repeat testing, imaging, or biopsy depending on total PSA, age, and exam) is often considered.
A ratio <10% is associated with a higher probability of prostate cancer and commonly prompts more urgent diagnostic work-up (prostate biopsy).
Absolute total PSA and clinical context (age, prostate exam, symptoms, prior PSA trend, recent ejaculation or instrumentation) must always be integrated before decisions are made.

Normal Range

≥25% (free-to-total PSA ratio)

FAQs

Q: What is the normal range for PSA free by age?

A: Free PSA absolute values aren’t usually age-specific; clinicians rely on the free-to-total PSA ratio: >25% suggests lower prostate cancer risk, 10–25% indeterminate, and <10% suggests higher risk. Total PSA age-based reference ranges commonly used are: <40: ≤2.5 ng/mL; 40–49: ≤3.5; 50–59: ≤4.5; 60–69: ≤6.5; 70–79: ≤7.5 ng/mL. Interpretation should be individualized with urology consultation for abnormal results.

Q: What if free PSA is high?

A: If your free PSA is high (a higher percentage of PSA circulating unbound), it usually indicates a lower likelihood of prostate cancer and more likely benign conditions such as BPH or inflammation. Doctors interpret the free/total PSA together with total PSA, age and exam findings. Next steps may include repeat testing, monitoring, MRI or biopsy only if other risk factors or abnormalities are present—discuss with your doctor.

Q: What does it mean if your prostate specific antigen is high?

A: A high prostate-specific antigen (PSA) level isn’t diagnostic of cancer. It can reflect prostate cancer but also benign prostatic enlargement, prostatitis, recent urinary procedures or ejaculation, or certain medications. Age and prostate size affect PSA. Doctors interpret absolute level, age-adjusted ranges and trends, and may repeat testing, perform a digital rectal exam, imaging, or recommend biopsy to determine the cause.

Q: How to convert free PSA to total psa?

A: To convert free PSA to total PSA you need the percent free PSA. Use: total PSA free PSA (percent free 100). For example, if free PSA 0.5 ng/mL and percent free 25%, total PSA 0.5 0.25 2.0 ng/mL. Ensure both values use the same units (ng/mL) and consult a clinician for interpretation.

Q: What is a good PSA score for a 70 year old?

A: For a 70-year-old, a PSA below about 6.5 ng/mL is often considered within the age‑adjusted normal range. Values above this or a rising trend, urinary symptoms, or an abnormal digital rectal exam usually prompt further evaluation (repeat testing, imaging, or biopsy). Discuss results with your clinician, since thresholds and management depend on overall health and clinical context.

Q: What is the danger zone for PSA?

A: PSA interpretation: under 4.0 ng/mL is usually considered normal, 4.0–10.0 ng/mL is a \