Management Guidelines

Serum Phenylalanine Levels | Food Patterns | Formula | Nutrition Education
Illness | Lifetime Diet | Maternal PKU | Clinic Format | Clinic Staff


Serum Phenylalanine Levels

Without early diagnosis and appropriate treatment, Phenylketonuria (PKU) leads to mental retardation. Loss of intelligence is preventable with good management. Serum phenylalanine levels of 1-10 mg/dL are safe and acceptable, but levels of 1-6 mg/dL are ideal and especially important for infants and young children. The current national standard of care in the United States is to maintain these safe levels throughout life. No one with PKU should ever be "taken off diet."

Once newborn children are under satisfactory management, a monthly serum phenylalanine (or "phe") level is recommended. This level is drawn at a monthly clinic visit. If that level is out of the recommended range, a mid-month follow-up level is requested.

Food Patterns

Children with PKU must eliminate high protein foods from their diets (meat, fish, dairy products, eggs, poultry) and restrict their intakes of moderate protein foods (potatoes, grains). As children grow older, they need to increase their intakes of low protein foods (certain fruits and vegetables, low protein breads and low protein pasta products) to maintain appropriate energy (calorie) intake and prevent hunger. Adequate formula intake plus low protein foods provide a generous amount of protein, phenylalanine at the requirement level, energy to support growth, and all essential nutrients.


Those infants and children who receive a consistent daily intake of a phenylalanine-free formula/medical food (roughly 85% of their protein needs and 90% of their energy needs) have the most stable and appropriate serum phenylalanine levels. The clinic policy is "formula first." Parents are taught that formula is given before other foods, both to meet nutritional needs and to satisfy appetite.

Nutrition Education

Teaching the children to manage their diets by themselves is an important aspect of the program, starting with "yes/no foods" and moving on to "how much." At the monthly clinics, nutrition education activities are provided for each age group to aid the children in learning about their diets.

Two concepts are reinforced by this clinic, the first being that the parent is the teacher. Materials, tools, and ideas with which the parent can continue to teach their child about the diet at home are provided. The importance of consistency and appropriate development of food habits are emphasized. The second concept is that of health. Children with well-managed PKU are normal, healthy children. Every possible attempt is made to treat them as such and not as if they have a disease. All aspects of the child-diet, physical fitness, self-esteem, and self worth-are considered. The consistent food patterns and routines established by parents in early childhood are essential for dietary compliance when the children are older and more independent.


During an illness or infection, it is important to maintain the formula intake as much as possible. The continuation of formula is to help prevent the breakdown of muscle protein during illness that will increase the level of phenylalanine in the blood. However, if a child refuses to drink formula, then whatever clear liquid the child's primary care physician recommends is suggested. Parents need to contact their child's primary care physician for management of the illness before calling the PKU Clinic staff.

Lifetime Diet

The current standard of care is a low phenylalanine diet for life. The PKU Collaborative Study documented long-term dietary intervention as the only method to achieve optimal intellectual ability. When children are taken off the low phenylalanine diet and their blood phenylalanine levels increase, their IQ or achievement test scores drop. Cranial MRI studies have documented abnormalities consistent with demyelination with the severity of changes correlating with poor dietary compliance. Central to long-term compliance is regular monitoring of progress: monthly (or more frequent) serum phe levels and food records are important "benchmarks of progress" for children and families.

Maternal PKU

Women with phenylketonuria face a special dilemma in planning a pregnancy. An elevated maternal phenylalanine level will damage a developing fetus. In the placenta, the fetus is exposed to phenylalanine levels that are 1.5 times greater than the mother’s levels. The higher the pregnant woman’s phenylalanine level, the greater the chance that the fetus will be damaged. Infants of mothers with uncontrolled blood phenylalanine levels exhibit microcephaly, mental retardation, heart defects, and growth retardation. The fetus of any woman who has blood phenylalanine levels greater than 6 mg/dl is at risk for being damaged.

There is research data that shows that with well-controlled blood phenylalanine levels, that is, within the normal range, a woman with PKU can have a healthy, normal baby. If maternal blood phenylalanine levels are kept within 1-4 mg/dl prior to conception and during pregnancy, the risk to the fetus is decreased. However, the underlying risks associated with any pregnancy are still present.

Many women with PKU find it very difficult to keep their phenylalanine level low enough to ensure a healthy pregnancy outcome. Some women choose to adopt children or to not have children of their own.

The risks associated with PKU and pregnancy and options for assuring a healthy outcome are first discussed with the family when the child with PKU is very young, and the discussion continues as the child gets older. It is hoped that an ongoing dialogue will help young women with PKU and their families understand and accept the guidelines, so that the consequences are well understood and appropriate decisions can be made.

A video presenting up to date information about maternal PKU and the importance of making well-informed decisions prior to pregnancy is available. Maternal PKU: Choices You Can Live With is available to view over the Internet, or may be ordered from the Children’s PKU Network. Click here for more information.

Clinic Format

A monthly clinic is held in Seattle at the University of Washington. It is always held on the third Wednesday of the month and the following Thursday. Instead of giving children individual appointments, children and their parents are seen in groups based on age. The children meet with nutritionists to work on a nutrition education project, while parents meet in a separate group to discuss issues related to raising a child with PKU. After the group time, the families meet individually with the pediatrician, nutritionist, and social worker.

This group format was selected for several reasons. First, it is a reliable and efficient way to educate children and parents and keep them up to date on recent developments in PKU management. Additionally, parents can support each other in important ways, and children benefit immeasurably from knowing other children with PKU who make the same food choices they do.

A clinic in Spokane is held about five times per year for families in Eastern Washington. Seattle-area families are strongly urged to attend the monthly clinic. For families who live too far away to attend monthly, a monthly serum phenylalanine level and three day food record is recommended. Experience has shown that this monthly feedback is essential to maintain good serum phenylalanine levels.

For our current clinic schedule, click here.

Clinic Staff

The Cristine M. Trahms Program for Phenylketonuria at the University of Washington is primarily funded by the Washington State Newborn Screening Program. The State Genetics Program provides families with formula (paid for by their medical insurance). The programs are closely coordinated to ensure follow-up and appropriate management of newborns identified with PKU.

C. Ronald Scott, MD, Clinic Director
Anne Leavitt, MD, Clinic Co-Director
Janie Heffernan, MS, RD, Nutritionist
Beth Ogata, MS, RD, Nutritionist
Mari Obara, MS, RD, Nutritionist
Janet Garretson, MSW, Social Worker
Jie Feng, MS, CGC, Genetic Counselor
Vicki Frasher, Patient Care Coordinator
Steve Sulzbacher, PhD, Consulting Psychologist


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