title: Neonatal 17-hydroxyprogesterone levels adjusted according to age at sample collection and birthweight improve the efficacy of congenital adrenal hyperplasia newborn screening.
abstract: BACKGROUND
  The primary concern related to congenital adrenal hyperplasia (CAH) newborn screening (NBS) is the high rate of false-positive results (FPR) associated with prematurity; false-negative results (FNR) can also occur due to precocious sample collection.
  
  
  OBJECTIVE
  To determine the neonatal 17-hydroxyprogesterone (N17OHP) normal range in newborns in Sao Paulo using different references according to age and birthweight (BW) and to establish the optimal NBS cut-off levels.
  
  
  METHODS
  Neonatal 17-hydroxyprogesterone levels from 271 810 newborns (NBs) according to sample collection time (G1: 48-<72 h and G2: ≥72 h) and BW (≤1500 g, 1501-2000 g, 2001-2500 and >2500 g) were evaluated. N17OHP was measured by an fluoroimmunoassay, and serum 17OHP was measured by liquid chromatography-mass spectrometry. Affected and asymptomatic NBs with persistently increased 17OHP levels were submitted to CYP21A2-sequencing.
  
  
  RESULTS
  Neonatal 17-hydroxyprogesterone levels in G1 were lower than G2 in all BW groups (P < 0·001). The FPR rate in G1/G2 was 0·2% using the 99·8th and 0·5% using the 99·5th percentile. The 99·8th percentile N17OHP value was the best cut-off for distinguishing between unaffected and affected NBs. Forty-four salt wasters, and five simple virilisers were diagnosed; N17OHP levels ranged from 93·3 to 2209·8 nmol/l, and no affected neonates with FNR were identified. The positive predictive value in G1 and G2 using the 99·8th percentile was 5·6% and 14·1%, respectively, and 2·3% and 7%, respectively, using the 99·5th percentile. Molecular tests identified two NBs with the nonclassical form among the 29 FPR.
  
  
  CONCLUSIONS
  Neonatal 17-hydroxyprogesterone levels adjusted to sample collection age and birthweight reduced the FPR, and the use of N17OHP values based upon the 99·8th percentile improved the NBS efficacy.
authors.affiliation: Associação de Pais e Amigos dos Excepcionais de São Paulo - APAE DE SÃO PAULO, São Paulo, Brazil.|Laboratório de Hormônios e Genética Molecular/LIM 42 - Disciplina de Endocrinologia e Metabologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Giselle Y
authors.initials: GY
authors.lastname: Hayashi
authors.affiliation: Laboratório de Hormônios e Genética Molecular/LIM 42 - Disciplina de Endocrinologia e Metabologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Carvalho
authors.affiliation: Laboratório de Hormônios e Genética Molecular/LIM 42 - Disciplina de Endocrinologia e Metabologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Mirela C
authors.initials: MC
authors.lastname: de Miranda
authors.affiliation: Associação de Pais e Amigos dos Excepcionais de São Paulo - APAE DE SÃO PAULO, São Paulo, Brazil.
authors.forename: Cláudia
authors.initials: C
authors.lastname: Faure
authors.affiliation: Associação de Pais e Amigos dos Excepcionais de São Paulo - APAE DE SÃO PAULO, São Paulo, Brazil.
authors.forename: Carla
authors.initials: C
authors.lastname: Vallejos
authors.affiliation: Laboratório de Hormônios e Genética Molecular/LIM 42 - Disciplina de Endocrinologia e Metabologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Vinícius N
authors.initials: VN
authors.lastname: Brito
authors.affiliation: Laboratório de Hormônios e Genética Molecular/LIM 42 - Disciplina de Endocrinologia e Metabologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Andresa De Santi
authors.initials: AS
authors.lastname: Rodrigues
authors.affiliation: Laboratório de Hormônios e Genética Molecular/LIM 42 - Disciplina de Endocrinologia e Metabologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Guiomar
authors.initials: G
authors.lastname: Madureira
authors.affiliation: Laboratório de Hormônios e Genética Molecular/LIM 42 - Disciplina de Endocrinologia e Metabologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Berenice B
authors.initials: BB
authors.lastname: Mendonca
authors.affiliation: Laboratório de Hormônios e Genética Molecular/LIM 42 - Disciplina de Endocrinologia e Metabologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Tânia A S S
authors.initials: TA
authors.lastname: Bachega
mesh_terms: D019326:17-alpha-Hydroxyprogesterone / Q000097:blood* / Q000592:standards; D000312:Adrenal Hyperplasia, Congenital / Q000097:blood / Q000175:diagnosis*; D000367:Age Factors; D001724:Birth Weight; D001800:Blood Specimen Collection / Q000379:methods; D002853:Chromatography, Liquid; D005189:False Positive Reactions; D015200:Fluoroimmunoassay; D006801:Humans; D007231:Infant, Newborn; D013058:Mass Spectrometry; D015997:Neonatal Screening / Q000379:methods*; D012016:Reference Values
chemical_list: D019326:17-alpha-Hydroxyprogesterone