Table of Contents

HK J Paediatr (New Series)
Vol 25. No. 1, 2020

HK J Paediatr (New Series) 2020;25:3-7

Original Article

Clinical Utility of Second-tier Testing in Newborn Screening for Congenital Adrenal Hyperplasia: The Hong Kong Experience

MCW Yeung, TCH Chan, CM Mak


Abstract

Objective: The present study aimed to evaluate the utility of steroid profiling using liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a second-tier test for congenital adrenal hyperplasia (CAH) newborn screening. Methods: The newborn screening results of 40,754 newborns who were screened for CAH from April 2016 to March 2019 were included in this study. First tier test involved measurement of 17-hydroxyprogesterone (17-OHP) in dried blood spot using dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA). Cases with positive first-tier screen were subjected to second-tier test utilizing LC-MS/MS to measure 17-OHP, androstenedione and cortisol in the same dried blood spot samples. Results: Of the 40,754 newborns screened, 422 (1.04%) were screen positive by first-tier test and required second-tier test. Among them, 4 (0.01%) were screen positive by second-tier test and were recalled for further workup. Two of whom were diagnosed with CAH. Also one neonate with negative screen was subsequently diagnosed with CAH during work up for fever and hyponatraemia and hyperkalaemia. The 2 true positive and 1 false negative cases are all salt-wasting 21-hydroxylase deficiency. The estimated incidence of classical CAH in the screened population was 1:13,585. Conclusions: Second-tier steroid profiling by LC-MS/MS can significantly reduce false positive rate and avoid unnecessary recalls in newborn screening for CAH. However, false negative screen still occurs and any patients with clinical features of CAH should receive diagnostic testing regardless of newborn screening results.

Keyword : Congenital adrenal hyperplasia; False positive; Newborn screening; Second-tier


Abstract in Chinese

 
 

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