If you're a man who takes the hair-growth drug Propecia, you should let your doctor know before you have your next PSA test, as it could affect the accuracy of the results.
The prostate-specific antigen (PSA) test measures an enzyme produced almost exclusively by the glandular cells of the prostate. It is secreted during ejaculation into the prostatic ducts that empty into the urethra. PSA liquefies semen after ejaculation, promoting the release of sperm.
Normally, only very small amounts of PSA are present in the blood. But an abnormality of the prostate can disrupt the normal architecture of the gland and create an opening for PSA to pass into the bloodstream. Thus, high blood levels of PSA can indicate prostate problems, including cancer.
A blood test to measure levels of PSA was first approved by the U.S. Food and Drug Administration (FDA) in 1986 as a way to determine whether prostate cancer had been treated successfully and to monitor for its recurrence. Today, however, PSA tests are FDA approved for prostate cancer detection and are widely used to screen men for the disease.
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Now research suggests that the hair-growth medication Propecia (finasteride) significantly lowers a man's PSA level, producing misleading results and potentially masking the presence of prostate cancer.
Propecia is the same medication as Proscar, which is used to control benign prostatic hyperplasia (BPH). The difference is the dosage -- 5 mg per day for Proscar vs. 1 mg for Propecia. Proscar is known to artificially lower PSA levels by about half, and doctors interpreting PSA results in these men compensate by doubling the PSA value. But Propecia's impact on PSA level has not been formally studied until now.
The researchers in the study which was reported in the journal Lancet Oncology (Volume 8, page 21) assigned 355 men age 40-60 to take either Propecia or a placebo (inactive pill) for 48 weeks. For analysis purposes, the men were grouped by age: 40-49 and 50-60. By the end of the study period, PSA levels among men in the younger group had dropped by an average of 40%; in the older group, PSA declined by an average of 50%. Among men taking the placebo, the PSA levels of the younger men had not changed, and the levels of the older men had risen by an average of 13%.
Bottom Line: If you use Propecia, be sure to let your physician know so that your PSA results can be adjusted accordingly.
