If the results of your DRE are abnormal or your PSA level is high, your doctor may suggest repeating the PSA test or may request an ultrasound, a biopsy, or other tests. The normal range for a PSA test is 0-4 nanograms per milliliter (ng/mL). A result over 10 ng/mL is considered high, and a result of 4-10 ng/mL is considered "borderline high."
If your PSA level is high, the doctor may want to do a biopsy, a procedure in which a small sample of tissue is removed for examination. A borderline PSA test result can be confusing because it does not always indicate the presence of prostate cancer. An elevated PSA level can be caused by other, noncancerous prostate conditions such as benign prostatic hyperplasia (BPH), a type of noncancerous prostate enlargement, and prostatitis, inflammation of the prostate.
If your DRE results are normal but your PSA level is borderline high, your doctor may want to do a transrectal ultrasound (TRUS), a test using sound waves produced by a device inserted into the rectum to produce a picture of the prostate. This ultrasound may identify abnormal areas of the prostate, which can then be biopsied. If the ultrasound is normal, however, you may simply need to repeat the PSA test after a few months. The biopsy is the only way to confirm a diagnosis of prostate cancer.
The following new PSA tests may also help a doctor to evaluate a patient whose initial PSA was borderline high:
- The percent free-PSA ratio is a blood test that measures how much PSA circulates by itself in the blood and how much is bound together with other proteins. If PSA results are borderline and percent free-PSA ratio is low (25 percent or less), prostate cancer is more likely to be present.
- Age-specific PSA reference ranges compare the PSA results of men in the same age group. If a man's PSA level is high compared to other men in his own age group, there is a higher chance that he may have prostate cancer.
- PSA density (PSAD) is found by dividing the PSA level by the size (volume) of the prostate as measured in the ultrasound. A high PSAD indicates a higher likelihood of prostate cancer.
- PSA velocity is a measure, based on two or more PSA tests, of the rate at which the PSA level has risen.
Because these tests are new, the medical community has not yet determined when and how the tests should be used. Your physician can help you decide whether any of these tests will be appropriate for you.