Interpreting Prostate Specific Antigen (PSA) Test Results

The Prostate Specific Antigen (PSA) test is used to screen for the possibility of prostate cancer. This routine blood test should be performed annually on every man aged 50 and above, or earlier if the man is at higher risk for prostate cancer. To perform the test, a small vial of blood is drawn and sent to a lab.

PSA test results come back as a number, the PSA level. PSA levels are expressed in nanograms per milliliter (ng/mL) and indicate the amount of Prostate Specific Antigen in the blood.

PSA is produced in normal prostates and a small amount of it is normally found in the blood. Higher levels in the blood can indicate some type of prostate trauma, inflammation, infection or cancer.

Traditional Interpretation

Traditional PSA test result strategies are relatively straightforward and don't allow consideration for age or health. Result ranges are as follows:

PSA level:

• < 4 ng/mL = normal
• 4-10 ng/mL = slightly elevated
• 10-20 ng/mL = moderately elevated
• 20-35 ng/mL = highly elevated

It should be noted: Many men with prostate cancer do not have elevated PSAs and most men with slightly elevated levels of PSA do not have prostate cancer. If PSA levels come back in the highly elevated range, it can indicate prostate cancer, and further diagnosis is indicated.

Other Interpretation Strategies

Levels of PSA in the blood are also affected by prostate size and weight and research has demonstrated that PSA levels increase with age. Some practitioners are now interpreting the normal PSA range based on age with the following chart:

• <2.5 ng/mL for men 40-49 years old,
  
• <3.5 ng/mL for men 50-59,
  
• <4.5 ng/mL aged 60-69, and
  
• <6.5 ng/mL for men 70 and older.

It should be noted that not all practitioners are using this strategy--you should be comfortable with the doctor you are seeing, and always seek a second opinion before a radical procedure or difficult decision.

Summary

In summary, the PSA test is a tool for screening for prostate cancer risk. It should be done annually for all men aged 50 years and older, and should be started earlier if a man is at significant risk.

Results of the PSA are not diagnostic of prostate cancer, and a high PSA number does not necessarily mean you have cancer. PSA test interpretation varies among health practitioners. The PSA test is best used to provide a "snapshot" of your prostate for your doctor to watch for trends that warrant further study.