The prostate-specific antigen (PSA) test is a medical procedure that provides your doctor with information about the possible presence of prostate cancer. The prostate is a small, walnut-shaped gland that sits below your bladder and produces semen.

PSA is a protein released by both cancerous tissue and noncancerous tissue. It can normally be found in small amounts in the blood. High levels of PSA may indicate the presence of prostate cancer. However, a variety of other conditions can produce an elevated PSA level. For example, an enlarged prostate or even riding a bike not long before the test can affect results. Consequently, there is a debate in the medical community about how or if PSA testing should be performed and how the results should be used.

Prostate Specific Antigen (PSA) Levels

Your PSA level is determined with a simple blood test. There is minimal risk other than the slight chance of infection from the needle stick, and few side effects besides minor bleeding and bruising. People who are uncomfortable with needles or blood draws may experience lightheadedness.

How the test results are interpreted involves a number of factors like your age and health history. Results are given in nanograms per milliliter (ng/mL). Numbers below 4.0 ng/mL are considered normal. However, some healthcare providers may use these age-based groupings to define normal for you:

• Ages 40 to 49: 0-2.5 ng/mL
• Ages 50 to 59: 0-3.5 ng/mL
• Ages 60 to 69: 0-4.5 ng/mL
• Ages 70 to 79: 0-6.5 ng/mL

If your PSA level rises from one test to the next over a period of time, that can indicate the presence of prostate cancer. However, PSA results alone are not conclusive since they might be caused by a noncancerous (benign) prostate condition. If your doctor suspects you have cancer, a biopsy of the prostate may be ordered to confirm the diagnosis.

PSA Testing Limitations

There are certain factors that can affect the results of a PSA test. They include:

• Conditions that raise your PSA level such as prostatitis (inflammation of the prostate)
• The natural increase in PSA level with age
• Decreases in PSA level caused by certain medications and by obesity
• Misleading results, including that an elevated PSA level doesn’t necessarily mean you have prostate cancer and a low PSA level doesn’t guarantee that you don’t have prostate cancer
• Tumors that are cancerous but wouldn’t produce symptoms in your lifetime if left untreated

Talk With Your Doctor

Ultimately, it is up to you and your doctor to decide if a PSA test is right for you. However, some form of prostate assessment is increasingly important the older you get.