What Is PKU Screening?
The content of phenylalanine is 0.06-0.18 mmol / L (1-3 mg / dl).
Screening for phenylketonuria (PKU)
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- Phenylketonuria (PKU) screening is an important test for newborn screening. Phenylketonurics (phenylketonurics; PKU) is a common amino acid metabolism disease, which is caused by enzyme defects in the phenylalanine metabolic pathway, which makes phenylalanine unable to be converted into tyrosine, resulting in Keto acids accumulate and are excreted in large amounts from the urine. The main clinical manifestations are low intelligence, seizures and reduced pigmentation. The disease is an autosomal recessive.
- Name
- Screening for phenylketonuria (PKU)
- category
- blood
- The content of phenylalanine is 0.06-0.18 mmol / L (1-3 mg / dl).
- Abnormal results: (1) Nervous system: there may be neurological abnormalities in the early stages, such as excitement, hyperactivity or drowsiness, atrophy, a few showed increased muscle tone, hypertenoid reflexes, and convulsions (approximately 25%), followed by mental retardation Increasingly, 80% have EEG abnormalities. BH4 deficient neurological symptoms occur earlier and are more severe, with reduced muscle tone, drowsiness, and convulsions. If untreated, they often die in early childhood. (2) Appearance: Hair, skin and iris become lighter in the months after birth due to insufficient melanin synthesis. Dry skin, often with eczema. (3) Others: Due to the excretion of phenylacetic acid in urine and sweat, it has a special rat urine odor. People to be checked: People whose parents have the above symptoms and whose newborns have the above symptoms.
- Inappropriate: None. Contraindications before examination: poor rest, improper diet, excessive fatigue. Requirement during inspection: Actively cooperate with the doctor.
- After 3 days of feeding the newborn, the blood from the roots of the feet is collected, absorbed on the regenerated thick filter paper, dried and mailed to the screening center. The Guthrie bacterial growth inhibition test is used for semi-quantitative determination. The principle is that phenylalanine can promote the inhibition of Bacillus subtilis was re-grown, and the content of phenylalanine in the blood was measured in the range of the growth circle. The colorimetric quantitative determination under the action of phenylalanine dehydrogenase was also used, and the false positive rate was low. When the phenylalanine content is> 0.24mmol / L (4mg / dl), which is twice the normal reference value, the phenylalanine and tyrosine should be re-examined or collected from venous blood. The concentration of phenylalanine in normal people is as high as 1.2 mmol / L (20 mg / dl), and the blood tyrosine is normal or slightly lower.
- Phenylketonuria, neural tube defects in children
- Cerebellar malformation, strange asynchronous state, unstable gait, abnormal gait