Prostate Specific Antigen (PSA)

PSA is a protein produced by the prostate gland, a male sex organ, as part of semen. The prostate is normally the size of a walnut and is situated below the urinary bladder. The prostate surrounds the initial part of the urethra, a tube that transports urine from the bladder to enable urination.

PSA prevents semen from becoming too thick and in this way it plays a role in the fertilization process. While the majority of PSA is secreted in the semen, a small portion of the protein regurgitates back into the blood as well. PSA levels can be affected by a patient’s age, normally increasing as the patients get older.

If a patient has high levels of PSA in his blood it may be suggestive of prostate cancer, however, for a definitive diagnosis a prostate biopsy is required (click on the TRUS biopsy link above to read more about this procedure).  It is also possible for other prostate pathologies to contribute to higher levels of PSA including benign prostate hyperplasia (BPH), prostatitis, acute or chronic infection or inflammation of the prostate, a catheter in the urethra or any insult or injury to the prostate.

Prostate biopsy entails removing a small piece of the prostate and examining it under the microscope to determine if the prostate gland is cancerous.  Therefore, checking PSA levels is a screening tool that can be used to identify the segment of the population who has a higher risk of harbouring prostate cancer.  After diagnosis, the level of PSA in a patient can assist the doctor in tailoring treatment for a patient.  Ongoing PSA monitoring also assists the doctor to gauge the effectiveness of treatment.

The information on this website is provided to reinforce any advice you have received from your GP and others involved in your care and is not intended to replace discussions with your doctor.