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.
What Lowers PSA Test Results
Other factors can artificially lower the PSA level.
- Certain medications used to control urinary problems from BPH and prostititis -- such as finasteride or dustasteride, which are prescription medications, or saw palmetto, an over-the-counter herbal remedy – can lower PSA levels by as much as 50 percent.
- New research shows that men who use common painkillers such as non-steroidal anti-inflammatory drugs (NSAIDs) and aspirin on a regular basis had PSA levels that were about 10 percent lower than the men who did not use them. (HealthNews, Sept 11, 2008)
- A lowering effect was seen for regular use of acetaminophen (Tylenol), although it did not reach statistical significance. (HealthDay, September 8, 2008)
What’s a Normal PSA Level?
Unfortunately for men, ‘normal’ seems to be a bit of a moving target. Because of various factors such as age and medications, PSA levels tend to fluctuate. One abnormal PSA test can be quite meaningless.
For instance, men with PSA numbers below 1 may still have progressive cancers. The National Cancer Society even reports that 1 out of 4 men with prostate cancer have relatively low numbers.
Alternately, men with PSA levels in the hundreds may have no sign of cancer.
Generally, test results are best used as indicators of changes in PSA levels over time. If the PSA number is going up, it is usually not a good sign. Certainly if it rises quickly -- within a year -- a test is always recommended.
That said, most doctors agree that a PSA level of 4.0 or below is considered to be safe and normal. Any consistent rating from 4.0 up to 10.0 is labeled suspicious and may require additional tests. Readings above 10.0 are often considered to be dangerous and may indicate that the cancer is spreading.
Currently, some new tests are being developed to complement or even replace the PSA test.
Talk With Doctor
Because there can be different reasons for an elevated PSA level – including prostate cancer, benign prostate enlargement, inflammation, infection and age – a man should discuss elevated PSA test results with his doctor.
PSA Test for Prostate Cancer: Advantages And Drawbacks
Other articles on prostate health by Steve Vogel
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