Free PSA Percentage (Free / Total PSA Ratio)
Hormones marker
Percent Free PSA
Free PSA Percentage (Free / Total PSA Ratio)
Ratio of Free PSA to Total PSA, expressed as a percentage: (Free PSA / Total PSA) × 100. The clinically actionable number that comes out of a reflex Free PSA test. Used to refine cancer risk when Total PSA is in the 4 to 10 ug/L diagnostic grey zone. Lower percentages indicate higher prostate cancer probability.
PED Notes
Most useful when Total PSA is between 4 and 10 ug/L. In that range, percent free PSA below 10% suggests roughly 50% probability of prostate cancer on biopsy, while above 25% drops the probability to roughly 8% (Catalona 1998). For bodybuilders with PED-driven Total PSA elevation (DHT derivatives, high-dose testosterone), a high percent free PSA is reassuring evidence that the elevation reflects prostatic stimulation rather than malignancy. A low percent free PSA in this same context still warrants urology referral; PED use does not override the cancer signal in the ratio.
When high
A high percent free PSA is reassuring (lower cancer probability).
- Above 25% in a Total PSA grey zone (4 to 10 ug/L) is associated with roughly 8% cancer probability on biopsy
- Pattern is more consistent with BPH than malignancy
- Monitoring is still appropriate: serial PSA every 6 to 12 months, especially on PEDs that stimulate the prostate
- No urgent intervention required from the PSA result alone
For PED users:
- Suggests current Total PSA elevation is more likely PED-driven prostatic stimulation than cancer
- Continue to monitor: do not assume the pattern is permanent
- Consider reducing or rotating off DHT derivatives if Total PSA is rising fast
When low
A low percent free PSA is concerning (higher cancer probability).
- Below 10% in a Total PSA grey zone (4 to 10 ug/L) is associated with roughly 50% cancer probability on biopsy
- 10 to 25% is the intermediate-risk range; cancer probability rises as the ratio falls
- This is a urology referral, not a watchful waiting result
- Urologist may proceed to multiparametric prostate MRI and / or targeted biopsy
- PSA density (PSA / prostate volume on MRI) and PSA velocity (rate of change over time) provide additional context
For PED users:
- A low percent free PSA does NOT get a pass because of PED use
- DHT derivatives can stimulate the prostate and elevate Total PSA, but they do not push the percent free ratio into the cancer-suspicious range; that pattern indicates intrinsic prostate pathology
- Stop DHT derivatives, retest after 4 to 6 weeks, and proceed with urology referral regardless of the retest result if the initial percent free was low
- Do not delay urology workup waiting for the retest
Confounders that affect the ratio:
- Recent ejaculation (within 48 hours of blood draw): can lower percent free PSA artificially
- Vigorous cycling, prostate massage, or recent DRE: can shift the ratio
- Acute prostatitis or UTI: changes both Total and Free PSA, distorting the ratio
- Sample handling: Free PSA degrades faster than Total PSA at room temperature; older samples can show falsely low percent free
- Always reflex on a fresh sample after addressing confounders before acting on a low ratio
History Chart
Reading History
Frequently Asked Questions
Reference Ranges
Standard Range
VitalMetrics Range