Weight-adjusted neonatal 17OH-progesterone cutoff levels improve the efficiency of newborn screening for congenital adrenal hyperplasia.
OBJECTIVE
To evaluate weight-adjusted strategy for levels of neonatal-17OHP in order to improve newborn screening (NBS) efficiency.


METHODS
Blood samples collected between 2-7 days of age from 67,640 newborns were evaluated. When N17OHP levels were ≥ 20 ng/mL, and a second sample was requested. We retrospectively analyzed neonatal-17OHP levels measured by Auto DELFIA- B024-112 assay, grouped according to birth-weight: G1: < 1,500 g, G2: 1,501-2,000 g, G3: 2,000-2,500 g and G4: > 2,500 g. 17OHP cutoff values were determined for each group using the 97.5(th), 99(th), 99.5(th) and 99.8(th) percentiles.


RESULTS
0.5% of newborns presented false-positive results using the cutoff level ≥ 20 ng/mL for all groups. Neonates of low birthweight made up 69% of this group. Seven full-term newborns presented congenital adrenal hyperplasia (CAH) and, except for one of them, 17OHP levels were > 120 ng/mL. Only the 99.8(th) percentile presented higher predictive positive value (2%), and lower rate of false-positives in all groups.


CONCLUSIONS
We suggest the use of 99.8(th) percentile obtained by weight-adjusted N17OHP values of healthy newborns to reduce the rate of false-positive results in NBS.
Associação de Pais e Amigos dos Excepcionais de São Paulo, Brazil.
Giselle
G
Hayashi
Cláudia
C
Faure
Maria Fernanda
MF
Brondi
Carla
C
Vallejos
Daiana
D
Soares
Erica
E
Oliveira
Vinícius N
VN
Brito
Berenice B
BB
Mendonca
Tânia A S S
TA
Bachega
D019326:17-alpha-Hydroxyprogesterone / Q000097:blood*; D000312:Adrenal Hyperplasia, Congenital / Q000175:diagnosis*; D001724:Birth Weight; D001938:Brazil / Q000453:epidemiology; D005189:False Positive Reactions; D005260:Female; D015200:Fluoroimmunoassay / Q000379:methods; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D015997:Neonatal Screening / Q000379:methods*; D011237:Predictive Value of Tests; D012016:Reference Values; D012189:Retrospective Studies; D018709:Statistics, Nonparametric
D019326:17-alpha-Hydroxyprogesterone