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Table 1 Justification and benefits of the neonatal BH4 loading test

From: Diagnostic and therapeutic recommendations for the treatment of hyperphenylalaninemia in patients 0–4 years of age


Criteria/benefit of the neonatal BH4 loading test


BH4 treatment is now available from birth in Europe (as well as USA)


The Phe concentration in the newborn with a genetic defect in phenylalanine metabolism is spontaneously evaluated


The neonatal test allows the early diagnosis of GTPCH or PTPS deficiency


The normalization of blood Phe concentration will be reached sooner in the responsive neonates


The 24-h test only delays the management of the condition by 24 h and allows treatment to begin within the first 10 days of life


A complete phenotype of the patient is generated (Phe level and BH4 responsiveness)


The parents are rapidly informed of the types of treatment that are available for their child


Some patients will be able to avoid the dietetic treatment from birth


The good safety profile of this molecule is well established


The neonatal test avoids performing a Phe load in young patients after the newborn period

  1. BH4 Tetrahydrobiopterin, GTPCH Guanosine triphosphate cyclohydrolase I, Phe Phenylalanine, PTPS 6-pyruvoyl-tetrahydropterin synthase