Jim,

There can be quite an overlap in terms of the amount of Cortisol that both a SW and a SV can produce. Some SW make very little some can make as much as a SV. 

Where you see the parallels particularly well are, if you look at a graph of the cortisol  response of a SW and a SV CAH person during the ACTH stimulation test, they respond the same way... they don’t make any more cortisol in response to the large exogenous ACTH dose. Their levels simply do not rise. In a non-CAH person, their levels of cortisol rise significantly during ACTH stim test. The fact that the levels do not rise in SW and SV means that in daily life and at any time they are under stress either because of injury or illness, they cannot mount a sufficient cortisol response. Therefore they need lifelong replacement cortisone.

In terms of an enzyme deficiency such as 21 hydroxylase, you are looking at a difference of a SW having 0-1% remaining enzyme activity compared to a SV having approximately 2% remaining enzyme activity. Not much difference at all. In terms of Aldosterone production it takes such a tiny amount of enzyme activity to make aldosterone that even with the 2% enzyme activity that the SV’s have, it is enough to get by. When a simple viriliser becomes ill though, they can slip over the edge, in terms of dehydration, easier than a non-CAH person. Some medicos’ suggests that SV’s live ’constantly on the edge of dehydration’.

All the best with your son and keep us posted.

Rosalie