Prostate specific antigen, or PSA, is a protein produced by normal cells as well as malignant cells of the prostate gland. The PSA test measures the concentration of PSA in a man's blood. For this test, a blood sample is sent to a laboratory for analysis.
Results are generally reported in nanograms of PSA per milliliter of blood (ng / ml). The concentration of PSA in the blood is frequently elevated in men with prostate cancer.