title: [What disorders suspect following an increase of phenylalanine on newborn screening?].
abstract: Screening for PKU, in France, is made on the 3rd day of life by measuring the concentration of phenylalanine in dried blood spot samples. In this study, the goal was to examine the final diagnosis of patients who showed a hyperphenylalaninemia during newborn screening laboratory. Over a period of 11 years from 1 February 2002 to 31 January 2013, all newborns with a phenylalanine concentration increase (>180 μmol/L) have been identified and the cause of this increase was noted. Of the 165,113 newborns screened, hyperphenylalaninemia was identified in 90 patients during the newborn screening laboratory. During this period 35% of cases were due to classical phenylketonuria or hyperphenylalaninemia. In 4.4% of cases, increase concentrations were due to other diseases (biopterine deficiency, galactosemia, MSUD). However, 48.9% of high concentrations have not been confirmed by a second sample and 11% were children who died rapidely during their first days of life. The positive predictive value (PPV) of the test with a threshold of positivity >180 μmol/L was 40%. Our study showed that the positivity threshold of 180 μmol/L proposed by the Association française pour le dépistage et la prévention des handicaps de l'enfant (AFDPHE) provides a comprehensive detection of all phenylketonuria cases as well as mild hyperphenylalaninemia permanent and transient cases. Eventhough the use of a higher threshold would have the advantage of increasing the PPV of the test, none the less we would have missed out on some cases to follow.
authors.affiliation: Laboratoire de biologie et de recherche pédiatriques, American Memorial Hospital, CHU Reims, France.
authors.forename: Marc-Antoine
authors.initials: MA
authors.lastname: Michel
authors.affiliation: ARCAMMHE, Alix de Champagne, CHU Reims, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Raucourt
authors.affiliation: ARCAMMHE, Alix de Champagne, CHU Reims, France, Service de néonatologie, Alix de Champagne, CHU Reims, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bednarek
authors.affiliation: Laboratoire de biologie et de recherche pédiatriques, American Memorial Hospital, CHU Reims, France, ARCAMMHE, Alix de Champagne, CHU Reims, France.
authors.forename: Roselyne
authors.initials: R
authors.lastname: Garnotel
mesh_terms: D001708:Biopterins / Q000172:deficiency; D005260:Female; D005602:France / Q000453:epidemiology; D005693:Galactosemias / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007231:Infant, Newborn; D008297:Male; D008375:Maple Syrup Urine Disease / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology; D015997:Neonatal Screening / Q000379:methods*; D010649:Phenylalanine / Q000097:blood*; D010661:Phenylketonurias / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology*; D015854:Up-Regulation
chemical_list: D001708:Biopterins; D010649:Phenylalanine
keywords: galactosaemia; hyperphenylalaninemia; newborn screening; phenylalanine; phenylketonuria