Q: Many of my friends who are also in their 50s have been getting a PSA test, and my wife has urged me to do the same. What does this test measure and what is its value?
A: The PSA test measures the level of prostate-specific antigen, a blood protein that is present in increased amounts in men with any of three diseases of the prostate: benign prostatic hyperplasia (BPH), prostatitis and prostatic cancer.
BPH is a non-cancerous enlargement of the prostate that interferes with urination by pressing on the urethra which carries urine from the bladder. BHP inevitably accompanies aging and causes some symptoms in about 75 percent of all men over 50.
Prostatitis, an inflammation of the prostate, is also common. Prostatitis can cause a burning sensation when urinating, increased frequency of urination along with a sensation of needing to go all the time even though only small amounts of urine are passed. The PSA test is not particularly useful for the diagnosis of these two types of prostatic disorders because they are not life-threatening and their presence is made apparent by symptoms.
The PSA test is valuable for the early detection of prostatic cancer which produces no symptoms in its initial stages, when it is most likely to be curable. Prostatic cancer, the most common cancer among men, affects about 10 percent of all men.
Dr. Patrick Walsh, director of the Department of Urology at Johns Hopkins University, recommends two measures for the detection prostatic cancer: an annual rectal examination to identify a lump or area of hardness in the prostate in all men over the age of 45, and a yearly PSA test in all men over 50. It is very important to understand than an elevated PSA detects the presence of prostatic disease. It does not necessarily show that prostatic cancer is present; and, of course the PSA is not elevated in other types of cancer. Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine and associate dean for faculty affairs at the school.