How much Floinef is she taking?  In my humble opinion (I’m not a medical person, just a mom of 2 SWCAH children), I’d rather see a low renin than a high oine in a child so young.  I agree the bloodpressure should be checked.  But, assuming it is OK and she is taking 2 or less tablets of Florinef a day (each tablet being .1mg), then I would relax and sit tight until the regular endo returns.  At such a young age, high doses of Florinef are not unusual.  My children were on 2 1/2 tabs a day in infancy and salt supplements too!  Eventually they went down to 1/2 a tablet a day (ages 3 thru 8).   Now they are back to 1 tablet a day as they are so physically active and sweat so much. 

Good luck, take care.

Michele