Accuracy of PSA Tests---Part 1

Many Factors Elevate and Lower PSA Results

Most men facing a PSA (prostate-specific antigen) test for prostate cancer may not realize that many factors can influence the result. Nor do doctors always provide patients with a list of things not to do or not to take before the test.

So here’s a partial list of things that affect a diagnostic PSA test, both up and down.

What Elevates the PSA Test

The higher a man’s PSA level, the more likely it is that cancer is present. Here are some factors that elevate a result:

* Age alone can increase PSA levels. The older a man gets, the likelier his PSA will rise, yet it may mean nothing. For instance, a man might have a PSA reading of 5.5 at seventy, and not have cancer; yet that score in a fifty-something would raise concern.

* Sex. Doctors generally recommend men should abstain from sex at least two days prior to testing. Studies show that ejaculation within that period before a PSA test may increase PSA levels in the blood.

* Stimulation of the prostate, such as a prostate massage or a long bike ride, could elevate PSA levels.

* Inflammation of the prostate gland. Prostate problems, such as benign prostatic hyperplasia (BPH) or prostatitis, can inflate PSA levels.

* Infections of the prostate may cause PSA levels to rise. These can produce no symptoms, so patients might not be aware of them.

* A man with a larger than average prostate may have a higher than normal PSA reading, even if this prostate is healthy. (A larger prostate produces more PSA into the blood.)

* Digital rectal exams and biopsies of the prostate may cause PSA levels to rise. It should be noted that an increase in PSA caused by a DRE is not thought to be significant enough to produce a false-positive result. On the other hand, a biopsy may elevate PSA levels for as long as four weeks.