What Is PSA?
Prostate-specific antigen (PSA) is a protein produced by both normal and cancerous prostate cells. A blood PSA test measures its concentration — elevated levels may indicate prostate cancer, but also benign prostate enlargement (BPH) or prostatitis.
PSA Levels by Age
| Age Group | Normal PSA (ng/mL) |
|---|---|
| Under 40 | Below 2.0 |
| 40–49 | Below 2.5 |
| 50–59 | Below 3.5 |
| 60–69 | Below 4.5 |
| 70–79 | Below 6.5 |
How to Interpret PSA Results
| PSA Level | Cancer Risk |
|---|---|
| Below 4.0 | Low risk — ~15% chance of prostate cancer if biopsied |
| 4.0–10.0 | Intermediate risk — ~25% chance; further tests needed |
| Above 10.0 | High risk — above 50% chance; urgent urology referral |
Free PSA Ratio
PSA exists in free and bound forms. A high free-to-total PSA ratio suggests BPH (benign enlargement), not cancer. A low ratio (<10–15%) increases cancer likelihood.
Non-Cancer Causes of High PSA
- Benign prostatic hyperplasia (BPH) — very common in older men
- Prostatitis (prostate infection/inflammation)
- Recent ejaculation within 48 hours
- Vigorous cycling or horseback riding
- Prostate biopsy or TRUS (raises PSA temporarily)
PSA Velocity
PSA velocity — the rate of rise over time — is as important as a single level. A rise of >0.75 ng/mL per year raises cancer concern even if absolute PSA is normal.
FAQs
Should all men get PSA screening?
Major guidelines differ — shared decision-making with your doctor is recommended for men aged 50–70, or 40–45 for high-risk groups (Black ethnicity, family history).
Can a normal PSA rule out prostate cancer?
No — up to 15% of cancers occur with PSA below 4. Digital rectal examination (DRE) complements PSA.
What happens after a high PSA?
MRI prostate scan, then targeted or systematic biopsy — not immediate biopsy from PSA alone.
Medical Disclaimer: PSA screening has both benefits and harms. Discuss whether screening is right for your age and risk profile with your GP or urologist.