Description:
Prostate Antigen (PSA) is a protein produced by the prostate gland. Although most PSA is carried out of the body in semen, a very small amount escapes into the blood stream. The PSA test is done on blood. Since the amount of PSA in blood is normally minute, the PSA test requires a very sensitive method based on monoclonal antibody technology. PSA in blood can be by itself as free PSA or it can join with other substances in the blood as bound PSA. Total PSA is the sum of free and bound forms. This is what is measured as the standard PSA test.