Prostate-specific antigen (PSA) also renowned as gamma-seminoprotein or kallikrein-3 (KLK3) is a glycoprotein enzyme encoded in humans by the KLK3 gene. PSA is a constituent of the kallikrein-related peptidase family and is secreted by the epithelial units of the prostate gland. PSA is produced for the ejaculate where it liquefies semen in the seminal coagulum and allows sperm to bathe without coercion. It is also accepted to be instrumental in dissolving cervical mucus permitting the entry of sperm into the uterus. PSA is present in little amounts in the serum of men with wholesome prostates, but is often increased in the occurrence of prostate cancer or other prostate disorders. Clinical guidelines for prostate cancer screening alter and are controversial due to doubt as to if the advantages of screening finally outweigh the risks of overdiagnosis and over remedy. PSA levels are monitored periodically (e.g., every 6-36 months) after treatment for prostate cancerous disease - more often in patients with high-risk infection, less often in patients with lower-risk infection. If surgical therapy (i.e., radical prostatectomy) is successful at eliminating all prostate tissue (and prostate cancer), PSA becomes untraceable inside a few weeks. A subsequent rise in PSA grade above 0.2 ng/dL is generally regarded as clues of recurrent prostate cancer after a fundamental prostatectomy; less routinely, it may easily indicate residual benign prostate tissue.