Normal value of phenylalanine in newborns

Many people do not understand neonatal phenylalanine, which is a condition called phenylalanineuria in newborns. In recent years, the incidence of this disease is relatively high. It has an important relationship with genetics. If it rises, it will cause great harm to the child's growth and intellectual development. The normal value of phenylalanine in newborns must be checked in time. Let us learn about this aspect below.

Normal value of phenylalanine in newborns

When the phenylalanine content is >0.24mmol/L (4mg/dl), which is twice the normal reference value, recheck or venous blood sampling should be performed for quantitative determination of phenylalanine and tyrosine. The normal phenylalanine concentration in humans is 0.06-0.18 mmol/L (1-3 mg/dl), while the plasma phenylalanine level in children can be as high as 1.2 mmol/L (20 mg/dl) or above, and the tyrosine level in the blood is normal or slightly low. Usually, the diagnosis can be confirmed when the child's serum phenylalanine level is above 1.2mmol/L (20mg/dl). Early clinical manifestations include yellow hair and pale skin, but this is nonspecific.

Phenylketonuria can be treated with diet. Since natural foods contain a certain amount of phenylalanine, and a low-protein diet can lead to malnutrition in patients, only a low-phenylalanine diet can be used for treatment. In other words, patients with phenylketonuria can only use special food for treatment throughout their lives.

Symptoms of phenylketonuria in newborns

Neonatal phenylketonuria is a rare disease in newborns and belongs to amino acid metabolic disease. If a baby has neonatal phenylketonuria, it is not easy to find. So what are the symptoms of neonatal phenylketonuria?

First of all, in terms of appearance, children with newborn phenylketonuria tend to have white skin and often have symptoms of eczema. Due to the reduced synthesis of melanin, the children's hair is light, dry, and colorless; the head circumference is relatively small, and the deciduous teeth grow slowly; there is an unpleasant odor of rat urine and mold in the sweat and urine; some also show symptoms such as irritability and restlessness in the early stages. Some children may have feeding difficulties, vomiting, restless sleep, and easy crying.

Secondly, in terms of intellectual development, children with neonatal phenylketonuria generally begin to show obvious symptoms of intellectual retardation 4 to 9 months after birth, especially language development disorders. These manifestations indicate that the brain has been damaged. Some children also have epileptic seizures, which mostly appear within 18 months after birth. The vast majority of children have mental and behavioral abnormalities. If they are not treated promptly and reasonably, they will eventually suffer from moderate to extremely severe mental retardation.