This test measures the size of the prostate gland and relates it to the level of a special protein in the blood. The protein is called prostate-specific antigen (PSA). This test is used to identify men who are more likely to have prostate cancer. The PSA density test may be better at this than the standard PSA test. However, many experts think PSA density values are misleading. They do not use this test to check for prostate cancer.

Who is a candidate for the test?

Men with a slightly high standard PSA test value, who have a normal rectal exam, are possible candidates for this test.

How is the test performed?

A blood sample is obtained first. This usually involves inserting a fine needle into a vein in the forearm or hand to draw blood. The blood sample is sent to the lab to measure the PSA level.

The size of the prostate is then measured by transrectal ultrasound. This test bounces sound waves off of the prostate gland using a rectal probe. The probe is a slender, flexible surgical instrument with a blunt bulb-type tip. It is used to explore the rectum. The PSA density test value is calculated by dividing the standard blood PSA level by the size of the prostate.