Hi Christi,
A stim test is when they give the patient an injection of synthetic ACTH, which causes the adrenal glands to try to make more cortisol. And then they take bloodwork at timed intervals, to see if your cortisol level rises like it should and how this effects other hormone levels like 17-ohp etc. An example would be if your son’s cortisol levels didn’t rise but his 17-ohp did, then they could be pretty sure he has CAH.