They are looking at hypoplasia because they are "presenting" so differently.  My younger son has produces no aldostorone whatsoever, but does produce coritsol, however is much lower than the "normal" range.  My older son has aldostorone and renin levels that are slightly low/elevated but not enough so to cause his "failure to thrive" so they ran a sit. test after his ACTH levels came back elevated, but not too high (121, the 4 month old had levels at 501).  The sit test showed insuff. coritisol production so they determined infact he had adrenal insuff.  Both boys had 17OHP levels that were in the 30’s.  They have also tested the level of long-chain fatty acids to rule out adrenoleukodystrophy. 

They say that genetic sequencing is the only "true" way to diagnois hypoplasia, we are awaiting the results on the older son, but it has been 3 weeks and I am just wanting to get the diagnosis so I can "move on" with this first chapter, and so I can educate myself on the diagnosis- knowledge is power after all! 

THANKS for the responses!  Even if my boys are diagnosed with hypoplasia, you might see more posts from me-  the treatments (other than those dealing with puberty issues- hypoplasia causes delayed pub) and such are identical, and this site has been a great resource to me in navigating all the meds, stress dosing and such that is all so new to me!