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How to Treat Phenylketonuria
PKU is not curable, but it is treatable with a special diet beginning at birth.
Women with PKU must follow the diet strictly both before and during pregnancy, maintaining a phenylalanine level <6 milligrams/deciliter (mg/dL) [<363 micromole/liter (µmol/L)], to prevent brain damage in the unborn baby.
Women with PKU need to follow a strict diet while pregnant to avoid serious birth defects.
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Low-Phenylalanine Eating Pattern
This strict diet significantly reduces the intake of phenylalanine (also referred to as “phe”) to a level that a person with PKU can handle without seeing harmful effects. Newborns require 40-60 mg/kg/day of phenylalanine to maintain adequate growth. For most older children and adults with PKU the safe range is 200-400 mg of phenylalanine per day. The diet consists of:
- Drinking phenylalanine-free medical formula, which provides calories, protein, vitamins, and minerals without phenylalanine. Phenylalanine-free medical formulas are manufactured for infants, children, and adults and are the most important feature of the diet for PKU.
- Starches, including bread, potatoes, corn, and beans must be restricted.
- Eliminating high-protein foods such as milk, meat, fish, chicken, pork, eggs, beans, and nuts.
- Eliminating foods and beverages made with aspartame, an artificial sweetener that contains phenylalanine.
Part of the treatment plan for PKU is regular monitoring of the level of phenylalanine in the blood. During infancy, the pediatrician may monitor the blood very frequently, as often as once or twice a week. Over time, blood monitoring may not be needed as frequently. The treatment goal is to keep the level of phenylalanine in the blood in the safe range between 2-6 mg/dL (121-363 µmol/L). The doctor or registered dietitian may also perform an occasional diet analysis to calculate the amount of phenylalanine being consumed and to check for potential nutrient deficiencies.