I want to imform you that even though your son may have to live with a low tolerance, it isn't really yhat bad. I am the most sever case of PKU that I have run across so far. My phe allowance is 225mg a day, or the equivalent of only 5 grams of protein, and I am 21 years old. I have not had a single level over 5 since I was in middle school (about age 13). It is tough, meaning going out with friends and really having to remind yourself that you can't snack as much as they can, but it isn't bad at all. Especially with all of the foods from places like Camrbrooke and recipes from sites like Cook4love, living with a low tolerance isn't hard at all.