I think, if I am correct, that Carol H was saying that her daughter had an ACTH stimulation test done.....not a test for her own naturally produced (endogenous) ACTH.

The amount of exogenous ACTH administered, via injection, during an ACTH stimulation test is quite a large, sudden amount compared to what we produce ourselves. In a ’healthy’ person, with an unimpeded steroid pathway, this administered dose of ACTH (tetracosactrin/cosyntropin or synacthen), causes the cortisol level to rise significantly. In a person  with an enzyme block in the steroid pathway at eg. the 21-hydroxylase level then the surge of ’ACTH’ cannot go to the end of the pathway to make extra cortisol, so it backs up, like in a traffic jam and the precursors rise, one of which is 17-hydroxyprogesterone (OHP). So, both the raised 17-OHP and insignificant or no cortisol rise are diagnostic for CAH.

In a severely affected CAH patient, it is not always necessary to do an ACTH test, as their baseline levels of 17-OHP are so elevated and cortisol levels are quite low/borderline. However in later-onset patients it is one way of defining the level of enzyme block, a little clearer.

Carol, how many days before the retest with the ACTH stim, did they take your daughter off her medications?

Rosalie