Michelle,

Our 3 year old SW daughter had renin issues early on.  We had thought we needed to "fast" before the draws.  Since we did, though, her levels would be off, and they would raise the florinef to the point of giving her high blood pressure.  She would also get beat red when upset and her head would sweat like a fountain.  Then, when we were told not to do that and she ate (or had her bottle) normally, we ended up going back down and getting more normal readings.  Look out for the blood pressure since they are raising the florinef. 

Our doctor is very clear on getting a plasma renin level and not a renin level.  two different things. 

Lastly, if the doctor or nurse in the office doesn’t take the blood themselves, make sure the child is laying down in the lab where the blood is being drawn or make sure the doctor knows that the child is sitting up by themselves or up in your lap when the test is being done.  The levels read differently when they are upright.

Good luck to you!

RebeccaM