What are the presentations of children with phenylketonuria?

Jocelyn 2022-03-30


Keturia is a genetic disorder. Hyperphenylketonemia is present in the neonatal period. Due to not eating, the concentration of phenylalanine and its harmful metabolites in the blood is not high, and there are no clinical manifestations at birth. If the newborn is not screened for phenylketonuria, with the extension of feeding time, phenylalanine and its harmful metabolites in the blood gradually increase, and clinical symptoms gradually appear. Generally speaking, symptoms can appear 3 to 6 months after breastfeeding, and symptoms are obvious at 1 year old. The above-mentioned children obviously have obvious symptoms of phenylketonuria: sparse and soft yellow hair, almost invisible eyebrows, fair skin, obvious smell; unstable walking, difficulty in crossing thresholds, no speech, only a few monophonic sounds. There was almost no response to the teacher's words. When he asks the teacher anything (if he wants to drink water, pee, or toys), he will show it with gestures such as fingers.

Phenylketonuria is caused by damage to the nervous system. In severe cases, it can cause early childhood death in children. The surviving children do not have the ability to take care of themselves due to severe intellectual impairment, which brings a heavy burden to the family and society. The disease is one of the few treatable inherited metabolic diseases. The above symptoms can be reversed after diet control and treatment, but the mental development lags behind and it is difficult to change. Efforts should be made for early diagnosis and treatment to avoid irreversible damage to the nervous system. Because early childhood is asymptomatic, laboratory testing must be used. At present, the commonly used detection methods are as follows:

Newborn Screening - After 3 days of feeding, the peripheral blood of the heel is collected, and the thick filter paper is absorbed, dried and mailed to the screening center for testing. When the phenylalanine content is 0.24mmol/L (4mg/dl), which is twice the normal reference value, phenylalanine and tyrosine should be re-examined or quantitatively measured by venous blood. The normal human phenylalanine concentration is 0.06~0.08mmol/L (1~3mg/dl), the plasma phenylalanine in children can be as high as 1.2mol/L (20mg/dl), and the blood tyrosine is normal or slightly lower what is pku.

Phenylketonuria diet health care.

The principle of diet is: not only to limit the intake of phenylalanine in the diet, but also to provide enough nutrients for growth and development. If dietary therapy is started 5 months after birth, most children are mentally retarded. When dietary therapy is started at the age of 4 to 5 years, it can only reduce convulsions and abnormal behaviors. As the newborn ages, the amount of phenylalanine used for protein synthesis will gradually decrease, and the amount required for metabolism and clearance will gradually increase. Phenylpyruvate also increases in the absence of pAH activity, so the amount of phenylalanine in the diet should gradually decrease with age. Babies can be fed special low-phenylalanine milk powder; low-protein foods such as starches, vegetables and fruits are added.