Can you tell me definitively whether the prostate-specific antigen (PSA)-lowering effect of alpha blockers is similar to, albeit less dramatic than, that of finasteride (Proscar)? Specifically, does doxazosin (Cardura) or terazosin (Hytrin) lower PSA? Do the OTC preparations, such as saw palmetto, which have weaker alpha-blocking properties, affect PSA levels?—JAMES A. SHUBIN, MD, Sebastopol, Calif.

The alpha-blocker class of medicines includes tamsulosin (Flomax), terazosin, and doxazosin. These agents do not have any significant influence on the value of PSA for the purpose of screening for prostate cancer. Finasteride can be expected to reduce PSA by 50% after 12 months. Thus, to obtain a “true” PSA level, one can double the value in such a patient. A baseline PSA should be done before initiation of treatment (Walsh PC, Retik AB, Stamey TA, Vaughan ED Jr. Campbell’s Urology. 8th ed. Philadelphia, Pa.: WB Saunders; 2002:3058).

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Saw palmetto has several possible mechanisms of action, including antiandrogenic effects and inhibition of 5-a-reductase isoenzymes. Therefore, one can expect that there might be some lowering of the PSA value due to this herbal remedy used for BPH.—David T. Noyes, MD (147-4)