Have the doctors done a 24 hour profile on your son, 17 OHP and cortisol?  With my son, (who is now on the pump) before he started using it, showed that he metabolised the hydro very quickly.  We discovered that he did better on smaller more regular doses, than by increasing the normal X3 doses a day.  Too much hydro can also cause high blood pressure, as far as I understand.  Since being on the pump my son’s fludro dose has gone down from 2 tabs a day to a quarter once a day. The only other thing is maybe his salt intake is too high. I do hope you find some answers soon. Wishing you and your son all the best Kathy