PSA (Prostate-Specific Antigen) Test

PSA, or Prostate-Specific Antigen, is a protein produced almost exclusively by the prostate gland, and measuring its level in the blood helps screen for and monitor a range of prostate conditions, including prostate cancer.

Small amounts of PSA normally leak into the bloodstream, but conditions that disrupt the normal architecture of the prostate — including cancer, benign enlargement, or inflammation — can all cause more PSA to enter circulation, raising blood levels.

Because PSA testing can sometimes lead to further investigation of prostate changes that would never have caused symptoms or harm during a man's lifetime, screening guidelines vary and often emphasize a shared discussion between patient and doctor about the potential benefits and downsides of testing.

When PSA is used, it's typically interpreted alongside other factors including age, rate of change over time, and sometimes a Free PSA ratio, to better estimate the likelihood that an elevated result reflects cancer versus a benign cause.