I have not heard of allergies being measured like this, but, I would say it was a high reading. I would have your son avoid peanuts completely and if you buy something that says made in a factory where peanuts are, I would not buy that either. They are a dangerous allergy.
I had a scratch test done yesterday. I had one that measured 15 by ?? and the dr said it was huge. They measure in millimeters so 25 mm would be 2.5 centimeters which is about an inch. He is highly allergic to peanuts.
Does that help?