If you look down the first pathways to the left you see he can make everything in that pathway naturally.  This includes corticosterone which is the pre cursor to aldosterone.  The interesting thins is that corticosterone is a glucocorticoid secreted by the cortex of the adrenal gland and is  primarily used as an indicator of stress levels. So really in asense he is getting "some" glucocorticoid there and all he is missing is whatever is not being made after Prenenolone which is illustrated below.  Perhaps therin lies the difference between why he does not need the high doses?  I am wondering if we are under estimating what the Corticosterone is doing for him and he needs to be on lower doses than what would be typical in 21 Hydroxylase?  Of course the other thing to be thrown into the pot is the severity with which he has a deficiency where 17 Hydroxylase is concerned?  May not be that bad either, and hence the reason why he is showing over suppression even on such low doses?  

Was he picked up with new born screening and if so I wonder what severity his 17 Hydroxylase deficiency is?  Perhaps you really need to cut right back in order to let him runa away a little and then  the doses in miniscule amounts thereafter?  It may need more frequent monitoring until your get it spot on though.

Cheers

Anne-Marie

Enzymatic pathways for Cortisol and Aldosterone:

	Desmolase		17-alpha-Hydroxylase		C-17-Lyase
Cholesterol	--------------------->	Pregnenolone	----------------------->	17-oh-Pregnenolone	------------------->	Dehydroepiandrosterone
		|		|		|
	3-beta-oh-steroid dehydrogenase	|	3-beta-oh-steroid dehydrogenase	|	3-beta-oh-steroid dehydrogenase	|
		Progesterone		17-oh-Progesterone		Androstenedione
	21-Hydoxylase	|	21-Hydroxylase	|	Peripheral tissues	|
		Deoxycorticosterone		11-Deoxycortisol		Testosterone
	11-beta-Hydroxylase	|	11-beta-Hydoxylase	|
		Corticosterone		Cortisol
	18-Hydroxylase	|
		18-oh-Corticosterone
	18-Oxidase	|
		Aldosterone