What does the Prostate-Specific Antigen, Total test measure?

Why is Prostate-Specific Antigen, Total measured?

PSA is the cornerstone blood biomarker for prostate cancer screening and post-treatment surveillance. Its strength lies in longitudinal trends and integration with free-to-total PSA ratio, clinical findings, and imaging rather than in a single threshold. Rising PSA velocity and persistently elevated values prompt further investigation, while stable low values offer reassurance. In survivors treated for prostate cancer, undetectable or stable PSA signals remission, whereas biochemical recurrence is defined by rising values.

Reference ranges

Standard reference

Commonly <4.0 ng/mL, with age-specific and risk-adjusted thresholds; there is no single threshold that excludes cancer # REVIEWER FLAG: PSA thresholds are age-specific, assay-dependent, and contested — reviewer to confirm framing and the age-adjusted intervals adopted by BiomarkersLabs.com.

Functional medicine optimal

Optimal PSA thresholds are debated and individualised by age, race, family history, and shared decision-making around screening benefits and harms; many guidelines avoid a single 'optimal' cut-off in favour of risk stratification.

Units

ng/mL, µg/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.