PSA

Definition

Prostate-Specific Antigen; is a protein produced by normal prostate cells. This enzyme participates in the dissolution of the seminal fluid coagulum and plays an important role in fertility. The highest amounts of PSA are found in the seminal fluid; some PSA escapes the prostate and can be found in the serum. This serum component has been used to track the response to therapy in men with prostate cancer.

The PSA level tends to rise in men with benign prostatic hyperplasia (BPH) and is a good marker for prostate volume. PSA levels are usually elevated in men with acute bacterial prostatitis. The most valuable measurement of PSA is its change over time rather than the actual serum level. No identifiable PSA level guarantees normalcy; in addition, no specific level indicates that a biopsy should be performed. Instead, PSA velocity or doubling time has been shown to be a more accurate and reliable predictor for recommending a prostate biopsy and treating patients with this...