The levels I mentioned before for each type of PKU would be levels off-diet, without formula.
The fact is, that because everyone is different, those numbers are just guidelines. There is no way to be sure what form of PKU you have without having a mutation test – a genetic test to show exactly what mutations you carry.
In my case, I have one mild mutation and one severe mutation, so I have moderate, or variant, PKU.
I have a fairly high tolerance for phe, apparently, as 30 years off-diet seems to have had no noticeable negative effect.
On Kuvan, my levels are excellent (last one was actually a bit low, at 1.6), while eating 45 grams of protein (plus taking 15 grams of protein equivalent in formula), as my mild mutation responds very well to Kuvan.