PSA testing

The PSA test is a widely used blood screen that helps detect prostate abnormalities, including prostate cancer, benign prostatic hyperplasia (BPH) and prostatitis. Before the test, men are advised to avoid ejaculation and vigorous exercise for 48 hours and to inform their doctor about any medications or recent procedures that could affect their results.

The test involves drawing a small blood sample from the arm, which is then analysed to measure PSA levels in nanograms per millilitre (ng/mL). While there is no universally ‘normal’ PSA level, general interpretations suggest that levels between 0-2.5ng/mL indicate low risk, 2.6-4.0ng/mL may warrant monitoring, 4.1-10.0ng/mL suggest a moderate risk with about a 25 per cent chance of prostate cancer, and levels above 10.0ng/mL carry a higher risk, with around a 50 per cent chance.

PSA levels naturally increase with age and some clinicians use age-specific reference ranges to guide interpretation: 0.5-0.7 ng/mL for ages 40 to 49; 0.7-1.0ng/mL for ages 50 to 59; 1.0-1.5ng/mL for ages 60 to 69 and 1.5-2.5ng/mL for 70 to 79-year-olds.

Elevated PSA levels can suggest prostate cancer but may also result from benign conditions such as BPH, prostatitis, recent ejaculation or vigorous exercise.

PSA testing offers several benefits:

• It can help to detect prostate cancer early, particularly aggressive types that benefit from prompt treatment
• It is widely accessible through the NHS for men aged 50 years and over, or from age 45 for those at higher risk
• Useful for monitoring prostate health over time.

However, PSA testing also has limitations:

• False positives are common, with many men undergoing unnecessary further tests and anxiety despite not having cancer
• False negatives can occur, meaning some cancers may be missed
• The test may also lead to overdiagnosis of slow  growing cancers that would not cause harm, resulting in unnecessary treatments that carry risks such as urinary, bowel and sexual dysfunction. Further investigations like MRI and biopsy can cause discomfort and emotional distress.

There is no national screening programme due to concerns about overdiagnosis and over-treatment, but men aged 50 years and over can request the test after discussing the risks and benefits with their GP.

The PSA test should be avoided within six weeks of a urinary infection or prostate procedure and within 48 hours of ejaculation or vigorous exercise. Drugs such as finasteride or dutasteride can lower PSA levels.

If a patient’s PSA level is elevated, the GP may repeat the test in six to eight weeks to confirm the result, as temporary factors can influence PSA levels. If levels remain high, further investigations may be considered to assess the cause.

These can include a digital rectal examination (DRE) to check for abnormalities in the prostate, a free-to-total PSA ratio to improve diagnostic accuracy, or advanced blood tests like the Prostate Health Index (PHI) or 4Kscore.

Imaging techniques such as MRI or ultrasound may be used to visualise the prostate. If cancer is suspected, a prostate biopsy may be recommended to obtain tissue samples for analysis.