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 in men and the paraurethral glands in women.[5]
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PSA is produced for the ejaculate, where it liquefies semen in the seminal coagulum and allows sperm to swim freely.[6] It is also believed to be instrumental in dissolving cervical mucus, allowing the entry of sperm into the uterus.[7]
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.[8] PSA is not uniquely an indicator of prostate cancer, but may also detect prostatitis or benign prostatic hyperplasia.[9]