If I am correct 30-80 ummol/L is the normal range for phenylalanine levels in people who do NOT have PKU. Doctors recommend that people who have PKU keep their phe levels between 120 and 360 ummol/L. Some doctors will allow adults to go up to 600 ummol/L, but below 360 is still the safest route.
Is your husband seeing a special doctor specifically for his PKU along with a metabolic dietitian? Most general physicians do not know enough about PKU to treat it. Do you live in the US? If so you could check out this link: http://www.macpad.org/page.aspx?id=92187 This will provide you with information on where the nearest metabolic clinic is to you.
The diet that he followed when he was a child was called a low protein diet. In most cases this diet excludes meat, dairy, beans, nuts, and most grain products. The diet consists mainly of fruits, veggies, snack foods in measured amounts, and specially made foods. These specially made foods are foods that are made to imitate things such as breads, pastas, and baked goods without having a high amount of protein in them. He also needs to look into finding a metabolic formula. Ask your husband about this, he might remember drinking a drink mix when he was little.
A lot of adults who have PKU have had this issue. Many years ago doctors believed that children could discontinue the low protein diet at about six years old, because that is when the brain is fully developed. They did not believe a fully developed brain could be harmed. Today doctors now know that to prevent future issues it is necessary to follow the low protein diet for life. Unfortunately this doctor was probably just follow normal procedure at that time.