Dear Doctor, I remember a nurse friend of mine saying that what you ingest within 24 hours of a blood draw can affect some readings. I assume the drawee fasts at least 12 hours before the blood draw. Thus, does drinking alcohol with 24 hours of a blood draw affect the PSA reading? Or coffee? Are there other substances which affect other test results?

Thank you for your informative column, -Dick

Hello Dick, From what I have read, both coffee and alcohol consumed withing 24 hours of a psa test can affect its level and are best avoided. I am not aware of the need to fast totally before the level is drawn but it is easiest to do a blood draw early in the day before eating.

Massage of the prostate through rectal exam, intercourse or riding on a motorcycle or bicycle can all increase psa levels and should also be avoided prior to blood draw.

As for your last question, many substances affect many things. As i mentioned in an earlier column, the psa level if increased should be repeated since there can be significant differences from test to test without obvious cause. -Ellar, M.D.