Neonatal 17-hydroxyprogesterone levels adjusted according to age at sample collection and birthweight improve the efficacy of congenital adrenal hyperplasia newborn screening.

INTRODUCTION: 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. CONCLUSION: 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.

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. SUBJECTS AND 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.

Weight-adjusted neonatal 17OH-progesterone cutoff levels improve the efficiency of newborn screening for congenital adrenal hyperplasia / Determinação de pontos de corte para 17OH-progesterona de acordo com o peso ao nascimento melhora a eficiência da triagem neonatal da hiperplasia adrenal congênita

OBJECTIVE: To evaluate weight-adjusted strategy for levels of neonatal-17OHP in order to improve newborn screening (NBS) efficiency. SUBJECTS AND 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 97.5th, 99th, 99.5th and 99.8th percentiles. RESULTS: 0.5 percent of newborns presented false-positive results using the cutoff level > 20 ng/mL for all groups. Neonates of low birthweight made up 69 percent 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 99.8th percentile presented higher predictive positive value (2 percent), and lower rate of false-positives in all groups. CONCLUSIONS: We suggest the use of 99.8th percentile obtained by weight-adjusted N17OHP values of healthy newborns to reduce the rate of false-positive results in NBS.

OBJETIVO: Avaliamos retrospectivamente os valores da 17OHP ajustados para o peso ao nascimento para melhorar a eficiência da triagem neonatal. SUJEITOS E MÉTODOS: 67.640 recém-nascidos com amostras coletadas entre 2-7 dias de vida. Uma segunda amostra foi solicitada na presença de testes com valores da 17OHP > 20 ng/mL. 17OHP dosada pelo método DELFIA- B024-112 e correlacionada com o peso ao nascimento: G1 < 1.500 g, G2 1.501-2.000 g, G3 2.000-2.500 g e G4 > 2.500 g. Pontos de corte da 17OHP foram determinados para cada grupo usando os percentis 97,5th, 99th, 99,5th e 99,8th. RESULTADOS: Falso-positivos ocorreram em 5 por cento dos resultados com o ponto de corte > 20 ng/mL, dos quais 69 por cento eram prematuros. Sete recém-nascidos apresentaram deficiência da 21-hidroxilase e, exceto em um, os valores da 17OHP foram > 120 ng/mL. Somente o valor da 17OHP do 99,8th apresentou maior valor preditivo positivo (2 por cento) e menor índice de falso-positivos. CONCLUSÕES: Sugerimos o valor da 17OHP do 99,8th ajustado para o peso ao nascimento para se reduzir a taxa de resultados falso-positivos da triagem neonatal.