What is Prostate Specific Antigen (PSA)?   The prostate specific antigen (PSA) test is a blood test used to help in the early detection of prostate cancer.   PSA, an ingredient of semen, is made by the prostate. Some PSA naturally leaks from the prostate into the bloodstream. The PSA test measures the amount of PSA in the blood. As a man ages more PSA leaks into the blood. Problems with the prostate, such as prostatitis (prostate infection), BPH (benign prostatic enlargement), or cancer, may cause extra PSA to enter the blood. A digital rectal exam (DRE) or prostate biopsy can also raise PSA levels. If a PSA test shows higher than normal blood levels of PSA, other tests are necessary to help determine the cause of the increase. More information related to this topic...