Sandra,

From what you've described, your son was given an ACTH stimulation test, which is THE test used by the medical profession to diagnose CAH.  CAH involves the inability of the body to produce cortisol.  When the adrenal glands are told to produce cortisol, and can't, large amounts of the precursor hormone----17-Hydroxyprogesterone---builds up.  Your son's stimulated 17-OHP number of 24,000 (probably in units of ng/dl), is not at all borderline and clearly shows an enzymatic block.  You could go ahead and get a DNA test, but, in my opinion, there is no need to do so

I know how hard it is to accept the fact that your child has a serious medical condition and has to be on medication for the rest of his life.  But, in your case, it sounds like the system worked....newborn screening picked up the fact that there was an abnormality and your child's doctors took all the right steps to verify a diagnosis, and initiate treatment.  Get a DNA test, if you want to, but if you're just trying to verify the fact that he HAS CAH, unfortunately, it seems pretty clear, from what you have said, that he does.