Hi Farrell and thanks for your suggestions!
I was just quite affraid that any blood or urine value could have been altered by eating something at breakfast. Maybe I'd better to have a sugar poor one on that morning. You know what, here in Italy Class 1 medical is quite hard, especially the initial (the aeronautics issues certificates) and blood/urine tests are strict, so pilots who undergo their Class 1 or Class 2 renewals
have to bear themselves with empty stomach since the previous evening and still waiting for ...their urine test to be done.
this all happens at 8:00am though