ABSTRACT
The serine protease PSA is primarily produced by prostate epithelial cells and secreted in high concentrations into the seminal fl uid, although other non-prostatic tissues such as the periurethral glands may produce PSA.1,2 Most PSA is complexed to α1-antichymotrypsin and α2-macroglobulin and is thought to be cleared through the liver, whereas free or unbound PSA may be cleared via the kidneys.3,4 As a result, the true half-life of PSA is partially dependent on the free-to-total ratio. In general, the serum
half-life of PSA after removal of all prostatic tissue is 2-3 days, but the free PSA component may have a signifi cantly shorter half-life of 2-3 hours. Several weeks are required for maximal clearance of PSA and initial testing should be performed 3-4 weeks after surgery.
