Can't help adding to this - after several years of taking my daughter for tests (12 to be exact). At first we would just do the tests at the time of the endo visit. I noted consistent differences in levels when comparing early AM tests to those done in the afternoon. Morning levels were usually higher and PM was low. The low PM reading had us reducing the meds... thinking we were giving her too much cortef. If the next time was an AM reading her levels came back way too high and we then we would lower the dose. Usually the high AM tests results were also associated with a bit excessive growth and less weight gain - an indication she was not getting enough cortef to suppress the adrenals. After experiencing this several times, we decided (endo included) to stick to one routine - the AM testing. Intrying to be a bit more scientific we also tried to keep it beore 10 AM. (Also part of the routine was to go for a special treat after - she alway chose McDonald's for breakfast - as a result she usually didn't eat beforehand.) Conceivably we could have also gone with consistently doing the afternoon testing and used the height/weight chart along with the results, but in the long run, I'm satisfied that the AM tests proved in her case to be the most useful ones. Blood work was usually done every 3 months. My daughter actually surpassed her predicted height by 2" - she's even taller than me. (She is now 15 and we still do something special after a blood test.) A note regarding the HPA-axis hypothalmic-pituitary-adrenal and Mara you put me up to the challenge to find a few sites for you... I've noted the discussion on times of ACTH surges and have always been told by the endo of a surge around 2- 3 am. I've found a few sites for that back this up... I've copied the important parts as well as the addresses... Here they are.... "Increasing levels of ACTH stimulate adrenocortical activity resulting in a rise in plasma cortisol with maximal levels occurring between 2 am and 8 am. This rise in cortisol dampens ACTH production and in turn adrenocortical activity. There is a gradual fall in plasma corticoids during the day with lowest levels occurring about midnight." http://www.msnews.org/jpred.htm “A brief review of the HPA physiology may be helpful in understanding this rationale. Acting primarily through the hypothalamus a fall in free cortisol stimulates the pituitary gland to produce increasing amounts of corticotropin (ACTH) while a rise in free cortisol inhibits ACTH secretion. Normally the HPA system is characterized by diurnal (circadian) rhythm. Serum levels of ACTH rise from a low point about 10 pm to a peak level about 6 am. Increasing levels of ACTH stimulate adrenocortical activity resulting in a rise in plasma cortisol with maximal levels occurring between 2 am and 8 am. This rise in cortisol dampens ACTH production and in turn adrenocortical activity. There is a gradual fall in plasma corticoids during the day with lowest levels occurring about midnight.” http://darkwing.uoregon.edu/~sshapiro/Pemphigus/DrugsUsedToTreatPemphigus.html