What is PSA?
Prostate-specific antigen (PSA) is a protein produced almost exclusively by the prostate gland. It is naturally present in the blood in small amounts. The prostate secretes PSA to help liquefy semen — it is not normally a cancer marker in isolation.
PSA levels rise when the prostate is enlarged, inflamed, infected, or cancerous — because more cells are producing more protein, or because the normal barrier between the prostate's ducts and the bloodstream is disrupted. A raised PSA is therefore a signal for further investigation, not a diagnosis.
PSA reference ranges by age
PSA rises naturally as the prostate grows with age. For this reason, a single "normal" upper limit doesn't apply to all men — age-adjusted ranges give a more accurate picture of whether a PSA result is concerning.
| Age group | Reassuring range | Borderline — review advised | Raised — specialist referral |
|---|---|---|---|
| Under 50 | 0–1.5 ng/mL | 1.5–2.5 ng/mL | > 2.5 ng/mL |
| 50–59 years | 0–2.0 ng/mL | 2.0–3.0 ng/mL | > 3.0 ng/mL |
| 60–69 years | 0–3.0 ng/mL | 3.0–4.0 ng/mL | > 4.0 ng/mL |
| 70–79 years | 0–4.0 ng/mL | 4.0–5.0 ng/mL | > 5.0 ng/mL |
What causes a raised PSA?
Many men are understandably anxious when they receive a raised PSA result. It is important to know that cancer is not the most common reason for a mildly elevated PSA:
Very Common — Benign
Benign prostatic hyperplasia (BPH)
An enlarged prostate produces more PSA simply because there are more cells. BPH is the most common cause of a mildly elevated PSA in men over 50. The PSA rise from BPH is usually proportional to prostate volume.
Common — Benign
Prostatitis
Prostate infection or inflammation can cause a significant and sometimes dramatic PSA rise — occasionally into double figures. Acute prostatitis should be treated and PSA re-tested 6–8 weeks later before any cancer investigation proceeds.
Temporary — Benign
Recent ejaculation or vigorous activity
Ejaculation in the 48 hours before a PSA test, or vigorous cycling or horse riding, can temporarily elevate PSA. Testing should ideally be delayed by 48 hours from either activity.
Temporary — Benign
Urinary tract infection (UTI)
Bladder and urinary infections can raise PSA temporarily. A raised PSA in the setting of a UTI should be re-tested 6–8 weeks after successful antibiotic treatment before further investigation.
Procedural
Recent prostate examination or catheterisation
Digital rectal examination (DRE), cystoscopy, or urinary catheterisation in the days before a PSA test can raise the reading. Ideally, PSA is drawn before any prostate manipulation.
Requires investigation
Prostate cancer
Cancer disrupts the normal architecture of the prostate, allowing more PSA into the bloodstream. However, prostate cancer PSA and BPH PSA can look identical on a simple blood test — which is why an MRI is usually the next step rather than immediate biopsy.
PSA velocity and trends over time
A single PSA reading gives limited information. The rate of change — PSA velocity — is often more informative than the absolute value. Key thresholds:
- A rise of more than 0.75 ng/mL per year is considered significant by BAUS, regardless of the starting PSA
- A rise of more than 25% of the baseline value in one year warrants specialist review
- A PSA that doubles in under 12 months is a particularly concerning pattern requiring urgent urology referral
- A slowly rising PSA from a low baseline (e.g. 0.8 to 1.0 over two years) in a man over 70 may be entirely consistent with normal prostate ageing
This is why serial PSA testing — over months to years — provides the most useful clinical picture. If you have previous PSA results from your GP, bring them to your urology consultation.
What happens after a raised PSA?
Should you have a PSA test?
The UK does not operate a national prostate cancer screening programme. The evidence shows that while PSA testing reduces deaths from prostate cancer, it also leads to some overdiagnosis and overtreatment of cancers that would not have caused harm. The decision is therefore personal and informed.
Consider discussing a PSA test with your GP or a urologist if you are:
- Over 50 years old — particularly if you have any urinary symptoms
- Over 40 with a first-degree relative (father or brother) who had prostate cancer
- Of Black African or Caribbean ethnicity — your lifetime risk of prostate cancer is approximately double the population average
- Concerned about prostate cancer for any reason — you are entitled to an informed discussion
Frequently asked questions about PSA
PSA naturally rises with age as the prostate grows. As a general guide: under 50 — below 2.5 ng/mL; age 50–59 — below 3.0 ng/mL; age 60–69 — below 4.0 ng/mL; age 70 and over — below 5.0 ng/mL. These are the thresholds that typically prompt specialist review, not absolute cutoffs. Your result should always be interpreted alongside your symptoms, prostate size, family history, and any previous PSA readings.
No — and this is critically important. In men with a PSA between 4 and 10 ng/mL (a common range of referral), only about 25–30% are found to have prostate cancer on biopsy. Benign enlargement (BPH) and prostatitis are far more common causes of a mildly elevated PSA. A raised PSA is a trigger for further investigation, not a diagnosis.
Avoid ejaculation and vigorous perineal activity (cycling, horse riding) for 48 hours before the test. Do not have a prostate examination or catheterisation before the test. If you have a urinary tract infection, wait until this is fully treated and 6 weeks have passed before testing. Finasteride and dutasteride (5-alpha reductase inhibitors taken for BPH) can halve PSA levels — your doctor should be informed if you take these, as results need to be doubled for interpretation.
PSA in the blood exists in two forms: "free" PSA (unbound) and PSA bound to proteins. A lower percentage of free PSA (free/total ratio below 10–15%) is associated with a higher risk of cancer, whereas a higher free PSA percentage suggests benign enlargement. The free-to-total ratio is sometimes measured alongside total PSA in borderline cases to refine the risk assessment without immediately proceeding to biopsy.
Most raised PSA results do not require emergency action. If your PSA is mildly elevated and you have no other concerning symptoms, arranging a specialist appointment within 2–4 weeks is appropriate. If you have bone pain, significant weight loss, haematuria (blood in urine), or a very high PSA (over 20 ng/mL), seek an urgent appointment. Privately, a urology consultation can usually be arranged within days.
A normal PSA provides useful baseline information and does not rule out cancer. Regular testing is valuable because PSA velocity (the rate of change) can be more informative than any single reading. Men who test regularly can track their PSA trend over years — which is often more reassuring, or more alerting, than a one-off result.