Question

How do I choose the best hospital for treating phenylketonuria? The patient is a male, aged 1 year and 6 months, with main symptoms including low intelligence, seizures during fever, and unclear speech. Symptoms appeared at 18 months old, and laboratory tests showed mild ketonuria.

Answer

A low phenylalanine diet is primarily suitable for patients with classic phenylketonuria and those with blood phenylalanine levels consistently higher than 1.22 mmol/L (20 mg/dl). Since phenylalanine is an essential amino acid for protein synthesis, its complete deficiency can also lead to nervous system damage. Therefore, infants can be fed with specially formulated low-phenylalanine formula milk, and during the weaning period, complementary foods should mainly consist of low-protein foods such as starches, vegetables, and fruits. The daily requirement of phenylalanine is approximately 50-70 mg/(kg.d) for infants under 2 months, 40 mg/(kg.d) for those between 3 to 6 months, and around 25-30 mg/(kg.d) for children up to 2 years old, with about 10-30 mg/(kg..d) for those over 4 years old. It is advisable to maintain blood phenylalanine levels between 0.12-0.6 mmol/L (2-10 mg/dl). Dietary control should last at least until after puberty. Beijing Children’s Hospital, Institute of Child Health Research, and Women’s and Children’s Hospital can conduct checks in this regard.