Prostate Specific Antigen Blood Test (PSA)
Prostate specific antigen (PSA) is an enzyme produced by the prostate which all men have in their bloodstream. The PSA blood test is a test which measures the amount of prostate specific antigen in a man’s bloodstream.
In general, a healthy PSA level range is between 0 – 4. Patients should seek further testing when the PSA level is above this — or increases between tests. PSA testing is very individualized and what is considered abnormal for one man may be normal for another.
The rate of rise of the PSA over time is called PSA velocity. A change in PSA of more than 0.5 ng/ml per year may indicate a presence of prostate cancer.
For example, a man goes for his routine screening PSA test and it comes back at 2.0 ng/mL. He is otherwise healthy and his physician is unconcerned by the result since 2.0 is in the “normal” range of 0 – 4 ng/mL. But last year his PSA level was 1.0 ng/mL and the year before it was 0.5 ng/mL. Due to the rate of rise (doubling each year), this indicates further evaluation may be necessary.
Most men (80%) with elevated PSA have serum levels in the range of 4.0 to 10.0 ng/ml. However, numerous studies have now shown that a high PSA velocity may signal a rapidly growing cancer regardless of how high the absolute PSA level is.
It is important to seek additional medical advice if your PSA comes back abnormal. Your physician may recommend a repeat test or biopsy which involves taking a small amount of tissue that is analyzed under a microscope. The sample is then given a Gleason Score which determines the existence or severity of cancer.