What does PSA Mean – Prostate Specific Antigen
What does PSA mean – Prostate Specific Antigen
What is PSA? Prostate Specific Antigen PSA, is an enzyme found in the blood produced exclusively by prostate cells. Normal levels of PSA in the blood are small amounts between 0-2.5 ng/ml. Higher than normal levels, greater than 2.5 ng/ml, can be caused by cancer or benign, non-cancerous conditions such as enlarged prostate, prostate inflammation, infection, or trauma. All elevated readings of PSA should be checked.
Occasionally, a Digital Rectal Exam, DRE, does not reveal any abnormalities, but the PSA is elevated. Sometimes the opposite is true, and PSA is normal, but the DRE is abnormal. For this reason, the Prostate Specific Antigen PSA blood test together with the DRE is best for early detection.
Normal prostate cells and prostate cancer cells make PSA even if they are outside the prostate. That is why PSA monitoring after treatment is so important. Returning prostate cancer cells, confined to the prostate or that have spread to the bone or lymph nodes, will cause the PSA to rise. Prostate Specific Antigen PSA is important for diagnosis, treatment and follow-up as well as useful for comparing treatment results.
How does Age Effect PSA?
Austrian Researchers in the Tyrol PCa Early Detection Program, (PLoS ONE. 10(7):e0134134, 2015), have researched what PSA levels within age ranges should raise concern about the likelihood of significant prostate cancer. Based on age, what PSA level might trigger a referral to a urologist? Using these PSA trigger levels they “detected all relevant PCa with a significant reduction of biopsies.”
|Age Range||PSA Trigger Levels|
|Less Than 49 Years||PSA 1.75 ng/mL|
|Between 50-59 years||PSA 1.75 ng/mL|
|Between 60-69 years||PSA 2.25 ng/ml|
|Greater than 70 years||PSA 3.25 ng/mL|
How is PSA measured?
PSA is measured by a simple blood test. The typical test for diagnosis and risk group determination is the “total PSA” which is simply a measure of all the PSA. Since the amount of PSA in the blood is very low, detection of it requires a very sensitive technology (monoclonal antibody technique).
What is “free PSA”?
Total PSA is the sum of the free and the bound forms. Most PSA binds to other proteins in the blood. The remaining unattached PSA is named “free” PSA. Men with a lower percentage of free PSA have a higher risk for prostate cancer. For example, a man whose total PSA is 6.0 ng/ml with a 10 percent free PSA has a higher likelihood of having prostate cancer than another patient whose total PSA also is 6.0 ng/ml but with 35 percent free PSA. Therefore a high free PSA percentage is good. Free PSA is not used to monitor results after treatment only to evaluate risk before diagnosis. The free PSA test is particularly helpful in situations where a biopsy is negative but the PSA is slightly high. If there is a low free PSA, another biopsy 6-12 months later is usually recommended. If it is high, then a longer wait is usually recommended.
The free PSA test is a road sign to help determine whether further work-up and follow-up is necessary. A high free PSA does not guarantee that a person is free of prostate cancer. In some cases, a biopsy of a nodule will turn up prostate cancer despite a low overall total PSA and a high level free PSA. The total PSA is what is measured with the standard PSA test. Return to the Compare Treatments page.