PSA

PSA - PROSTATIC SPECIFIC ANTIGEN

Several years ago, a substance was discovered in the blood normally produced by the prostate gland (the male reproductive gland at the base of the bladder which produces the ejaculate during orgasm.) This substance, known as the prostatic specific antigen (PSA), is normally produced by the prostate in a small amount. During disease states, the prostate releases more of this into the blood stream and can be detected through a blood test. The disease states which produces an elevation include injury, infection, and most importantly, cancer. As such, this blood test has been introduced to aid urologists in rendering care to male patients in an attempt to detect prostate cancer at its earliest possible stage, and thereby hopefully, making the cancer more amenable to curative therapies.

The prostatic specific antigen should not be considered as a "screening test" in that it cannot stand alone in the detection of prostate cancer. Rather, the prostatic specific antigen is an additional tool with a history and physical examination most importantly including the digital rectal exam in evaluating male patients, specifically to determine whether or not prostate cancer is present.

The normal range for the laboratory which we use for prostatic specific antigen (PSA) is between 0 - 4.0. Values falling within this range are considered normal and are not indicative of diseased states. Prostate cancer can exist in patients with normal PSA values; therefore, the rectal examination is important and is not replaced by this blood test. Values of the PSA greater than 4 and less than 10 are considered in an equivocal range. Values elevated to this extent can be elevated for a variety of reasons. Occasionally, rarely, the rectal examination itself can elevate the prostatic specific antigen. Recent prostatic infection, injury, and even perhaps sexual activity can cause the elevation to be in this range. Prostate cancer itself can also cause an elevation into the range of between 4 and 10. Values greater than 10 are significant, in that many of these values are indicative of a prostate cancer.

When patients have elevated prostatic specific antigen values and a normal rectal examination, the first thing that is done is that the prostatic specific antigen blood test is repeated. Laboratory errors can occur, and before proceeding to more invasive testing, a simple repeat of the value is indicated. If the repeated value is elevated, a discussion with the physician will occur as to what options to take next. The options on a confirmed elevated prostatic specific antigen include: (1) Careful observation with a repeat of the prostatic specific antigen several weeks to months later or (2) Obtaining a transrectal ultrasound, and if indicated, biopsy of the prostate.

If option (1) is chosen, it is very important for the patient to take seriously his obligation to return to the urologist for a repeat prostatic specific antigen blood test and rectal examination. Option (2) involves the insertion of a probe into the rectum to visualize the prostate with ultrasonic waves, similar to sonar or radar. No radiation is used during this test. The transrectal ultrasound can visualize the prostate to determine if any abnormal areas exist. This technology, while not being precise enough to be a screen or replace the digital rectal examination and prostatic specific antigen, will occasionally detect areas of abnormality which can be biopsied.

Hopefully, this explanation will serve to characterize what the PSA is and how it is used as a part of the comprehensive urologic evaluation for early detection of prostate cancer. If you have any questions, please write them down and ask them, as understanding will greatly reduce anxiety and promote a partnership between the physician and the patient in health care.