That when you say his 17 OHP levels were in the 500’s that this meant ng/dl as 500’s in nmol/L would be extremely high and I would certainly have made sure you had him treated right away--not left over the weekend without treatment.  500 in nmol/L would be well over 15’000 and very high indeed.  I’d say that anything higher than 10nmol/L was a problem in a child with normal functioning adrenal glands if we were speaking in nmol/L not ng/dl.  The reason why I say this is because 10nmol/L is in the 300’s where ng/dl  is concerned.  That may be "normal" were kids without CAH is concerned or should be lower I would have thought.  Our kids have higher levels because of reasons I covered in the above post.  500’s in ng/dl would be 15nmol/L or higher.