Michele, Our endo suggested we get the blood drawn first thing of a morning, and it was not necessary to fast. He indicated to us that the pituitary gland kicks in about 11-12 at night, and the reading early of a morning would give a better indication of the levels and whether the hydrocortisone was "fooling" the system into not making the hormones that have hi levels. He also has my girls take their prednisone just before bedtime, that way they have a high level of the hydrocortisone in their system, and the pituitary doesn't produce more. Hope this makes sense to you. By doing this, the dr has been able to reduce the girls meds considerably. For instance, with my youngest (15), she went from 45 mg cortef a day to 15 mg prednisone, and now she's down to only 5 mg prednisone. We go back next month to see if the 5mg is working sufficiently. Good Luck! And God Bless. Janice Aldridge