The Use of Liquid Chromatography Tandem Mass Spectrometry to Improve Newborn Screening for Congenital Adrenal Hyperplasia in New Zealand

Newborn screening for congenital adrenal hyperplasia (CAH) prevents the severe clinical complications that can occur in babies with the condition in the first few weeks after birth. The screening test is the measurement of 17-hydroxyprogesterone (17OHP) by immunoassay in dried blood specimens collected 48-72 hours after birth. Screening is sensitive for the severest form of CAH but is confounded by a high false positive rate. Babies with milder forms of the condition may benefit from early treatment, can be missed by screening. This thesis has two aims: Firstly, to improve screening specificity by incorporating a second-tier steroid profile test using liquid chromatography-tandem mass spectrometry (LCMSMS) and secondly, to identify novel bloodspot markers that may improve screening sensitivity for CAH. In a prospective study, the existing second-tier screening immunoassay was replaced with a LCMSMS test incorporating five steroids. Second tier 17OHP, 21-deoxycortisol and steroid ratio parameters were evaluated in a series of studies before a new laboratory screening protocol was developed and modelled using data collected over a 4-year period (232,542 specimens and 35 residual specimens from babies with CAH). In a separate study, a LCMSMS method to measure 41 ketosteroids in bloodspot specimens was developed and evaluated and then applied to 53 specimens from babies with CAH and 389 specimens where a false positive screening result was encountered. During the study, 11 CAH cases were detected, and the positive predictive value of screening improved from 1.1% to 48.7% after the introduction of LCMSMS. Analysis of retrospective cases was modelled to show that the sensitivity using the new protocol would improve from 78% to 87%, primarily due to the incorporation of 21-deoxycortisol as an additional second-tier marker. Evaluating the data from the expanded steroid study, 7 novel newborn screening markers, more sensitive than 17OHP, for the detection of classical CAH were identified. Two novel bloodspot markers, 21-deoxycortisone (receiver operated characteristic area under the curve 0.9906) and 11-ketotestosterone (AUC 0.9876) were more accurate markers than 21-deoxycortisol (AUC 0.9623) for the detection of classical CAH, and 21-deoxycortisone as a single marker had a specificity of 100%.

Name thesis:degree_name

PhD

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Health Sciences

Grantor dc:publisher

ResearchSpace@Auckland

Year dc:date.issued

2025

Author dc:creator

• de Hora, Mark Robert

Advisors dc:contributor.advisor

• Hofman, Paul
• Albert, Ben

• congenital adrenal hyperplasia
• newborn screening
• mass spectrometry
• bloodspot analysis
• steroids

Statement dc:rights

• Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Licence dc:rights.uri

• https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm

Handle dc:identifier.uri

https://hdl.handle.net/2292/72915

OAI identifier oai:identifier

oai:researchspace.auckland.ac.nz:2292/72915