Its not necessary but it could help
Well, if there is any fasting blood work involved, I would say yes, it should be avoided for at least 12 hours, other than that, I really do not think so, but I would just to be on the safe side.
A blood alcohol level is generally taken, which may not be provided to you.
An abnormal blood alcohol read on on a physician flags the patient as a potential alcoholic.
So, besides interfering with test readings, you end up with an comment in your health records that someday may come back to haunt you.