The prednisone has a much longer half life than cortef.  The Dr says is stays in her blood much longer.  He said Cortef does not stay in the blood very long.  Since Erin (14 now) was always forgetting her mid-day dose -- we never seemed to get that routine down -- and when I switched ped endos to Dr. Migeon at Hopkins --he suggested the switch to prednisone.  He had just had a heart attack, and agreed sincerely that mid-day dosing was too hard to remember for him, too.  She was always undersuppressed, even when she took her meds regularly.  The prednisone brought her levels all the way down, right away.  And she's been a different girl since then.  Was it the switch to HS from middle school?  Is it her age or maturity?  Was it the meds?  I'm sort of voting for the meds.  My son (17) has never been undersuppressed, although he has the same mid-day problem.  Dr. Migeon left him on cortef since he's doing fine w/ twice a day doses (15 mg am and pm).  I'm the only one who took dex (but that was during the third pregnancy).  That's not much experience w/ it at all.

Lynn