Prostate specific antigen (PSA) is a protein made by both normal prostate cells and cancerous prostate cells. PSA is found in the blood and can be measured with a blood test. The test results will show the level of PSA in your blood as nanograms of PSA per millilitre (ng/mL) of blood.
There isn’t one normal PSA level for everyone. If your PSA level is above 3 ng/mL (called the threshold), this may be a sign of prostate cancer. But younger people or people who have a family history of prostate cancer may have a lower threshold. PSA levels can vary from day to day. If your PSA is higher than expected, your GP will usually repeat the test to help work out your risk of prostate cancer.
Your PSA level can be raised even when you don’t have cancer. Other common causes of raised PSA levels include benign prostate hyperplasia, recent sexual activity, an infection in the prostate, or a recent digital rectal examination. Some people with prostate cancer have normal PSA levels for their age range.
Free PSA or free-to-total test
Your doctor may also suggest that you have a free PSA test. This test measures the ratio of free PSA to total PSA in your blood. Free PSA is PSA that is not attached to other blood proteins. This test may be suggested if your PSA level is 4–10 ng/mL and your doctor is not sure whether you need a biopsy. A low free-to-total PSA ratio may be a sign of prostate cancer.
→ READ MORE: Digital rectal examination
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Prof Declan Murphy, Consultant Urologist, Director – Genitourinary Oncology, Peter MacCallum Cancer Centre and The University of Melbourne, VIC; Alan Barlee, Consumer; Dr Patrick Bowden, Radiation Oncologist, Epworth Hospital, Richmond, VIC; Bob Carnaby, Consumer; Dr Megan Crumbaker, Medical Oncologist, St Vincent’s Hospital Sydney, NSW; Henry McGregor, Health Physiotherapist, Adelaide Men’s Health Physio, SA; Jessica Medd, Senior Clinical Psychologist, Department of Urology, Concord Repatriation General Hospital and Headway Health, NSW; Dr Gary Morrison, Shine a Light (LGBTQIA+ Cancer Support Group); Caitriona Nienaber, 13 11 20 Consultant, Cancer Council WA; Graham Rees, Consumer; Kerry Santoro, Prostate Cancer Specialist Nurse Consultant, Southern Adelaide Local Health Network, SA; Prof Phillip Stricker, Chairman, Department of Urology, St Vincent’s Private Hospital, NSW; Dr Sylvia van Dyk, Brachytherapy Lead, Peter MacCallum Cancer Centre, VIC.
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