Prostate
PSA measurements provide information about the prostate gland. Results can be affected by several prostate conditions and should always be interpreted alongside age, symptoms and clinical context.
Free prostate specific antigen (free PSA)
Free PSA measures the portion of PSA circulating without being bound to proteins. It is interpreted alongside total PSA and may provide additional information when assessing the likelihood of benign versus malignant prostate conditions.
Free : total PSA ratio
The free-to-total PSA ratio compares free PSA with total PSA. In selected situations it can provide additional context when a total PSA result is raised, although it does not diagnose prostate cancer on its own.
Total prostate specific antigen (PSA)
Total PSA measures prostate-specific antigen circulating in the blood. PSA can rise with prostate cancer but also with benign enlargement, inflammation and other non-cancerous causes, so it is not diagnostic on its own.