Phenylketonuria (PKU) is an inherited genetic metabolic disorder in which the enzyme required to digest phenylalanine (PHE), a part of protein, is either missing or does not work correctly. As a result of this missing or defective enzyme, individuals with PKU, if untreated, will develop high levels of PHE in their blood. This PHE can affect brain development and function, causing a variety of issues for individuals with PKU. By following a strict low PHE diet, individuals with PKU can avoid any problems associated with high PHE levels. People with PKU still need to eat protein so that they can grow and maintain their body functions and muscles. The amount of PHE that an individual is permitted varies depending on the specific genetic defect, but typically ranges from 150 to 600 milligrams of PHE per day. People with some enzyme activity, who are considered to have a variation of PKU typically referred to as hyper-PHE, can often eat more PHE.

The PKU diet includes a specially manufactured low protein foods, fruits and most vegetables. Food items that must be avoided include meat, fish, poultry, dairy products, baked goods and eggs. All food items eaten by a person with PKU must be monitored and PHE must be calculated on a daily basis. People with PKU are required to drink a formula supplement that provides them with the other amino acids in protein.

Studies show that approximately 1 of every 10,000 (NIH) babies will be born with PKU. Most cases of PKU are detected through a newborn screening blood test conducted before the baby leaves the hospital.

For more information on the newborn screening programs in other states, please see the Save Babies Through Screening Organization.