when my daughter was 5 she was on a really large dose of Cortef throughout the day.  But her levels were way off and she was going into Adrenal Crisis quite often.  The endo said that the cortef was no longer working and he switched her to dexamethasone.  Her levels have been fine for the past 5 years and are just now starting to act up again.  We are thinking of switching to another medication for awhile to see if there will be any changes.

Ask the endo to change her to a different medication.