Immunoassay for measuring prostate-specific antigen

Prostate-specific antigen (PSA) is a serine protease composed of a single-chain glycoprotein with about 240 amino acids. In this article, we discuss the application of serum immunoassays to the measurement of PSA. Clinical use of this assay is problematic because a large percentage of patients with prostate cancer have serum PSA results within the reference range, and most PSA elevations are caused by benign prostatic hypertrophy. Clinical judgement and knowledge of the test's limitations are essential for proper interpretation of results. This is the final article of a four-part continuing education series on chemistry. Other articles focused on rapid immunoassays, immunosensors, and general principles of immunoassays. Following this series, participants should be able to identify the limitations of immunoassays, describe the factors that affect PSA assays, and interpret results from these assays.