Patient's question:
What is the normal value of phenylalanine in newborns? The screening results say 1.9 is normal, and do I still need to retest? The child was screened at 12 days, and the hospital called me today with the results.Doctor's answer:
The normal blood phenylalanine level in children with phenylketonuria (PKU) is less than 120 μmol/L. In classic PKU, blood Phe concentration is >1200 μmol/L; in moderate PKU, 360–1200 μmol/L; and in mild PKU, blood phenylalanine is less than 120–360 μmol/L. Currently, individual 1.9 has mild PKU and requires early treatment, primarily through dietary therapy.Newborn screening for phenylketonuria: After newborns are fed for 3 days, blood is collected from the heel. If the phenylalanine content is >0.24 mmol/L (4 mg/dL), which is twice the normal reference value, a repeat test should be conducted or venous blood should be drawn to quantitatively measure phenylalanine and tyrosine.