I am 32 with Classical PKU and on 7 exchanges. I have been around this since birth with only 1/2 exchange increase.
My last blood test result was only 230uml when I had 15 1/2 exchanges the previous day. I've been told the more natural protein you have the higher the phe result should be but I've had a much lower phe result??
I've also heard if the body doesn't get enough protein it will try and get this from muscle and can make the levels rise as of a result.