What is the protein-specific antigen (PSA)?
PSA is an enzyme produced by the prostate. The primary role of PSA is to liquefy semen in order to facilitate the movement of sperm. PSA is present primarily in the semen, but it can also be found in the blood or bound to two proteins: alpha 1 antichymotrypsin (ACT) and alpha-macroglobulin (AMG).
What is a PSA test?
A PSA test measures the amount of free and bound PSA in the blood. For this test, a blood sample is analyzed in the lab. The level of PSA in the blood is usually measured in nanograms of PSA per milliliter of blood (ng/mL). Combined together, the digital rectal exam (DRE) and the PSA test are methods used for the early detection of prostate cancer.
Who should have a PSA test?
If you are over 50 years old, you should consider having a PSA test done. If you are under 50 years old but at a higher risk for prostate cancer, a screening strategy may be recommended, beginning at 40 or 45 years old. Discuss the advantages and risks of the PSA test with your doctor.
What can I learn from a PSA test?
A raised PSA level can be a sign of one of the following problems:
- An enlarged prostate (benign prostatic hyperplasia)
- Inflammation or infection of the prostate (prostatitis)
- Prostate cancer
Many men that have a high PSA level do not have prostate cancer. On the other hand, some men with prostate cancer have a normal PSA level. Your doctor will take into consideration other factors, such as family history, and will have you undergo other tests, such as a digital rectal exam, before deciding whether you should consult a specialist.