The best thing is to try and exercise quite a bit the day or two before the test. Also... I had heard taking 4 or 5 aspirin an hour before the test throws it off for some reason. Niacin tablets and someone else had mentioned cranberry juice all seem to help clean the system as well. I had random UA's, the GCMS type, randomly once a month for five years. The only time I failed was when I used the Vale's sucker punch.