Prostate-specific antigen
Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), P-30 antigen, is a glycoprotein enzyme encoded in humans by the KLK3 gene. PSA is a member of the kallikrein-related peptidase family and is secreted by the epithelial cells of the prostate gland. PSA is produced for the ejaculate, where it liquefies semen in the seminal coagulum and allows sperm to swim freely. It is also believed to be instrumental in dissolving cervical mucus, allowing the entry of sperm into the uterus. PSA is present in small quantities in the serum of men with healthy prostates, but is often elevated in the presence of prostate cancer or other prostate disorders. PSA is not uniquely an indicator of prostate cancer, but may also detect prostatitis or benign prostatic hyperplasia. Medical diagnostic uses Prostate cancer Screening Clinical practice guidelines for prostate cancer screening vary and are controversial, in part due to uncertainty as to whether the benefits of screening ultimately outweigh the risks of overdiagnosis and overtreatment. In the United States, the Food and Drug Administration (FDA) has approved the PSA test for annual screening of prostate cancer in men of age 50 and older. The patient is required to be informed