This test is used to detect Prostate Specific Antigen (PSA). PSA is a protein produced only in the prostate gland. The prostate gland is a doughnut-shaped gland located in a man’s pelvis in the small space between the bae of the penis and the bladder. The prostate makes the fluid that nourishes sperm and carries sperm during ejaculation. The amount of PSA produced by the prostate gland can be helpful in detecting prostate cancer. This test is commonly used with the digital rectal exam to screen for prostate cancer. If you have prostate cancer a PSA can be an important tool used to follow the response to treatment for the cancer. In general, serum PSA levels increase due to physical changes to prostate architecture caused by trauma, infection, inflammation, prostate manipulation, benign prostatic hypertrophy (BPH) or serum PSA concentrations between 4.0-10.0 ng/mL. Alternatively, percent free PSA may be used to determine the relative risk of prostate cancer in individual men.