Total PSA

What it measures, and what changes the number.

Prostate specific antigen (PSA) is a protein made by cells of the prostate gland. Total PSA measures both the form that circulates freely and the form bound to other proteins in the blood.

It is often ordered with free PSA, and the two are used to calculate the free to total PSA ratio. Results are also commonly tracked over time rather than read as a single value.

Several things around collection can change the number, including recent ejaculation, vigorous cycling, a prostate examination, urinary catheterisation or prostate procedures, so labs sometimes ask about these. Different immunoassay platforms and calibration standards give somewhat different results, which is why serial tests are ideally run at the same lab. Reports may list it as PSA, TOTAL or PSA (Antígeno prostático específico).

Reference ranges labs publish

Each lab states an interval for its own method and the population it measured. They differ, they are not interchangeable, and none of them is a verdict on a single result.

Often read alongside: Free PSA, Free/total PSA ratio

Blood test glossary