Later, severe brain problems occur, such as mental retardation and seizures. Every state now screens the blood phenylalanine level of all newborns at about 3 days of age. This test is one of several newborn screening tests performed before or soon after discharge from the hospital. Usually, a few drops of blood are obtained by a small prick on the heel, placed on a card, and then sent for measurement. Newborn screening allows early identification and early implementation of treatment.
Some phenylalanine is needed for normal growth.
This requires a diet that has some phenylalanine but in much lower amounts than normal. Instead, measured amounts of cereals, starches, fruits, and vegetables, along with a milk substitute are usually recommended. Phenylalanine free formulas are available for all age groups. In some clinics, a phenylalanine 'challenge' may be suggested to evaluate whether or not the child continues to require a low phenylalanine diet. This test identifies those few persons with a transient or 'variant' form of the disorder.