Fifty years of newborn screening for congenital hypothyroidism: current status in Australasia and the case for harmonisation.

OBJECTIVES: Since its implementation 50 years ago in Quebec, Canada, newborn screening for congenital hypothyroidism has become one of the most successful public health measures worldwide. Screening programmes across Australia and New Zealand are characterised by significant commonalities in screening algorithms, and a high degree of regional cooperation in harmonisation efforts. We aimed to conduct a comprehensive survey of current performance and practices related to the total testing process for congenital hypothyroidism screening and provide recommendations for harmonisation priorities within our region. METHODS: A survey was conducted involving the six newborn screening laboratories which provide complete geographic coverage across Australasia. Approximately 360,000 newborns are screened annually. Survey questions incorporated pre-analytical, analytical, and post-analytical aspects of the screening programmes and an extensive 5-year (2016-2020) retrospective analysis of individual programme performance data. Responses from individual screening programmes were collated. RESULTS: The uptake of newborn screening was over 98% for the six major jurisdictions. All programmes have adopted a single-tier thyroid stimulating hormone (TSH) strategy using the Perkin Elmer GSP instrument. Significant similarities exist between programmes for recommended age of collection and recollection protocols for low birthweight newborns. The process for the determination of TSH cutoffs varies between programmes. TSH lower cut-offs for borderline-positive and positive notifications between 12-15 and 12-25 mIU/L blood, respectively. Recall rates vary between 0.08 and 0.20%. The case definition for congenital hypothyroidism generally includes biochemical and radiological parameters in addition to the commencement of thyroxine. All programmes reported collecting biochemical and clinical data on infants with positive screening tests, and positive predictive values vary between 23.6 and 77.3%. Variation in reported incidence (1:1,300-2,000) cannot be entirely explained by cutoff or recall rate (although one programme reporting fewer cases includes only permanent disease). CONCLUSIONS: Despite similarities between newborn screening algorithms for congenital hypothyroidism across Australia and New Zealand, differences in reported programme performance provide the basis for further harmonisation. Surveillance of a large population offers the potential for the ongoing development of evidence-based screening guidelines.

Implementing steroid profiling by liquid chromatography-tandem mass spectrometry improves newborn screening for congenital adrenal hyperplasia in New Zealand.

OBJECTIVE: To evaluate the impact of a liquid chromatography-tandem mass spectrometry (LCMSMS) second-tier test on newborn screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH) in New Zealand. DESIGN: In a prospective study, a LCMSMS method to measure 17-hydroxyprogesterone (17OHP) was adapted to measure four additional steroids. Steroid concentrations were collected on all second-tier CAH screening tests while protocols remained unchanged. Steroid ratio parameters with recommended or published screening cuts-offs were evaluated for their impact on newborn screening performance. MEASUREMENTS: Precision, accuracy, linearity and recovery of the second-tier LCMSMS method were evaluated. Second-tier specimens were divided in 3 groups; newborn screening bloodspots from neonates with confirmed CAH (n = 7) and 2 groups specimens from neonates with a birthweight (BW) ≤1500 g (n = 795) and with a BW > 1500 g (n = 806) with a negative newborn screening test. Six protocols using four steroid ratio parameters were evaluated. The sensitivity, specificity, false positive rate and positive predictive value of screening was calculated for each protocol. RESULTS: The LCMSMS method was sufficiently accurate and precise to be used as a second-tier test for CAH. Screening sensitivity remained at 100% for each protocol apart from (17OHP + androstenedione)/cortisol when the highest cut-off of 3.75 was applied. The false positive rate was significantly improved when (17OHP + androstenedione)/cortisol and (17OHP + 21-deoxycortisol)/cortisol were evaluated with cut-offs of 2.5 and 1.5 respectively (P < .01) and both with a positive predictive value of 64%. CONCLUSIONS: A second-tier LCMSMS newborn screening test for CAH offers significant improvements to screening specificity without any other changes to screening protocols.

The impact of demographic factors on newborn TSH levels and congenital hypothyroidism screening.

CONTEXT: Optimal newborn screening thyroid-stimulating hormone (TSH) cut-offs are contentious. Analysis of demographic factors that impact screen TSH levels may help explain international variance and provide guidance to screening programmes. OBJECTIVE: To determine the influence of demographic factors on newborn screening TSH levels and screening performance parameters. DESIGN AND SETTING: National, retrospective population study using blood spot TSH cards from the New Zealand newborn screening programme in 2010-2015. PATIENTS: 325 685 blood spot cards. MAIN OUTCOME MEASURES: Likelihood of exceeding specific TSH thresholds (TSH ≥5, ≥10 and ≥15 mIU/L) and group-specific screening performance parameters. RESULTS: The likelihood of high TSH levels differed between ethnic groups. Pacific Island infants were more than twice as likely to have high-normal TSH levels (≥5 and ≥10 mIU/L) and nearly twice as likely to have a positive screen (≥15 mIU/L) as New Zealand Europeans. Maori or Chinese ethnicity, male sex, younger gestational age and greater socio-economic deprivation scores were also associated with high-normal TSH levels. At a TSH threshold ≥15 mIU/L, screening sensitivity was lowest (88.89% vs 95.83% overall) and PPV greatest (88.89% vs 62.84%) amongst Asian infants. Early samples were more than three times as likely to reach the screen-positive threshold and more likely to yield a false-positive result (PPV 20.00% vs 68.87%, P = 0.004). CONCLUSIONS: Newborn TSH levels are impacted by a number of demographic variables, particularly ethnicity and age at sample collection. Screening performance may be improved through the use of targeted thresholds.

Evaluation of the revised New Zealand national newborn screening protocol for congenital hypothyroidism.

OBJECTIVE: The aim of this study was to assess the performance of the revised New Zealand (NZ) newborn screening TSH cut-offs for congenital hypothyroidism (CHT). METHODS: Screening data over 24 months were obtained from the NZ newborn metabolic screening programme, which utilizes a 2-tier system of direct clinical referral for infants with markedly elevated TSH, and second samples from those with mild TSH elevation. We evaluated the impact of a reduced TSH threshold (50 to 30 mIU/l blood) for direct notification and a lower cut-off (15 to 8 mIU/l blood) applied to second samples and babies older than 14 days. RESULTS: In 2013 and 2014, 117 528 infants underwent newborn screening for CHT. Fifty-two CHT cases were identified by screening (47 general newborn population, five repeat testing in low-birth-weight infants) and one case was missed. Thirty-two infants with screening TSH ≥30 mIU/l were directly referred at a median of 9 days (5-14) and 15 with TSH 15-29 mIU/l were referred after a second sample at a median of 20 days (9-52, P < 0·001). All directly referred infants were confirmed as CHT cases with no earlier referrals as a result of the reduced threshold. The lower TSH cut-off applied to second samples lead to the identification of six extra cases of CHT (15% increase) from seven extra clinical referrals. CONCLUSIONS: The NZ screening programme achieved a 15% increase in CHT case detection for minimal increase in workload or anxiety for families of healthy infants. A further decrease in the threshold for direct referral may allow earlier diagnoses.

A Positive Newborn Screen for Congenital Hypothyroidism in a Clinically Euthyroid Neonate-Avoiding Unnecessary Treatment.

Newborn screening for congenital hypothyroidism (CH) has dramatically improved the neurocognitive outcomes for newborns with a confirmed positive screening test result. However, screening yields a small number of false positive and false negative results. This report describes the first known case of familial dysalbuminaemic hyperthyroxinaemia presenting with a positive newborn thyroid stimulating hormone screen. This condition is characterized by artefactually elevated free tetraiodothyronine (T4) and triiodothyronine (T3) levels due to increased albumin binding and subsequent dissociation during laboratory assays but normal true free thyroid hormone and thyroid stimulating hormone (TSH) levels in a clinically euthyroid subject. This highlights the need to take care when attributing clinical significance to discordant results.

The use of liquid chromatography-tandem mass spectrometry in newborn screening for congenital adrenal hyperplasia: improvements and future perspectives.

Newborn screening for congenital adrenal hyperplasia using 17-hydroxyprogesterone by immunoassay remains controversial despite screening been available for almost 40 years. Screening is confounded by poor immunoassay specificity, fetal adrenal physiology, stress, and illness which can result in a large number of false positive screening tests. Screening programmes apply higher screening thresholds based on co-variates such as birthweight or gestational age but the false positive rate using immunoassay remains high. Mass spectrometry was first applied to newborn screening for congenital adrenal hyperplasia over 15 years ago. Elevated 17-hydroxprogesterone by immunoassay can be retested with a specific liquid chromatography tandem mass spectrometry assay that may include additional steroid markers. Laboratories register with quality assurance programme providers to ensure accurate steroid measurements. This has led to improvements in screening but there are additional costs and added laboratory workload. The search for novel steroid markers may inform further improvements to screening. Studies have shown that 11-oxygenated androgens are elevated in untreated patients and that the adrenal steroidogenesis backdoor pathway is more active in babies with congenital adrenal hyperplasia. There is continual interest in 21-deoxycortisol, a specific marker of 21-hydroxylase deficiency. The measurement of androgenic steroids and their precursors by liquid chromatography tandem mass spectrometry in bloodspots may inform improvements for screening, diagnosis, and treatment monitoring. In this review, we describe how liquid chromatography tandem mass spectrometry has improved newborn screening for congenital adrenal hyperplasia and explore how future developments may inform further improvements to screening and diagnosis.

The risk of classical galactosaemia in newborns with borderline galactose metabolites on newborn screening.

Newborn screening (NBS) for classical galactosaemia (CG) facilitates early diagnosis and treatment to prevent life-threatening complications, but remains controversial, and screening protocols vary widely between programmes. False-negatives associated with first-tier screening of total galactose metabolites (TGAL) are infrequently reported; however, newborns with TGAL below the screening threshold have not been systematically studied. Following the diagnosis of CG in two siblings missed by NBS, a retrospective cohort study of infants with TGAL just below the cut-off (1.5 mmol/L blood) was conducted. Children born in New Zealand (NZ) from 2011 to 2019, with TGAL 1.0-1.49 mmol/L on NBS were identified from the national metabolic screening programme (NMSP) database, and clinical coding data and medical records were reviewed. GALT sequencing was performed if CG could not be excluded following review of medical records. 328 infants with TGAL 1.0-1.49 mmol/L on NBS were identified, of whom 35 had ICD-10 codes relevant to CG including vomiting, poor feeding, weight loss, failure to thrive, jaundice, hepatitis, Escherichia coli urinary tract infection, sepsis, intracranial hypertension and death. CG could be excluded in 34/35, due to documentation of clinical improvement with continued dietary galactose intake, or a clear alternative aetiology. GALT sequencing in the remaining individual confirmed Duarte-variant galactosaemia (DG). In conclusion, undiagnosed CG appears to be rare in those with TGAL 1.0-1.49 mmol/L on NBS; however, our recent experience with missed cases is nevertheless concerning. Further work is required to establish the optimum screening strategy, to maximize the early detection of CG without excess false-positives.

The impact of prolonged, maternal iodine exposure in early gestation on neonatal thyroid function.

Context: Hysterosalpingography (HSG) using oil-soluble contrast medium (OSCM) improves pregnancy rates but results in severe and persistent iodine excess, potentially impacting the fetus and neonate. Objective: To determine the incidence of thyroid dysfunction in newborns conceived within six months of OSCM HSG. Design: Offspring study of a prospective cohort of women who underwent OSCM HSG. Setting: Auckland region, New Zealand (2020-2022). Participants: Offspring from the SELFI (Safety and Efficacy of Lipiodol in Fertility Investigations) study cohort (n=57). Measurements: All newborns had a dried blood spot card for TSH measurement 48 hours after birth as part of New Zealand's Newborn Metabolic Screening Programme. Forty-one neonates also had a heel prick serum sample at one week to measure thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3). Maternal urine iodine concentration (UIC) and TSH in the six months after OSCM HSG were retrieved from the SELFI study for analyses. Primary outcome: Incidence of hypothyroidism in the neonatal period. Results: There was no evidence of primary hypothyroidism on newborn screening (TSH 2-10 mIU/L). All neonates tested at one week had normal serum TSH, FT4, and FT3 levels. However, increasing maternal peak UIC levels during pregnancy were associated with lower TSH levels (p= 0.006), although also associated with lower FT4 levels (p=0.032). Conclusions: While pre-conceptional OSCM HSG in women did not result in neonatal hypothyroidism, gestational iodine excess was associated with a paradoxical lowering of neonatal TSH levels despite lower FT4 levels. These changes likely reflect alterations in deiodinase activity in the fetal hypothalamic-pituitary axis from iodine excess. Trial registration: https://anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12620000738921, identifier 12620000738921.

Cortisol response to synacthen stimulation is attenuated following abusive head trauma.

BACKGROUND: Child abuse and other early-life environmental stressors are known to affect the hypothalamic-pituitary-adrenal axis. We sought to compare synacthen-stimulated cortisol responses in children who suffered inflicted or accidental traumatic brain injury (TBI). METHODS: Children with a history of early-childhood TBI were recruited from the Starship Children's Hospital database (Auckland, New Zealand, 1992-2010). All underwent a low-dose ACTH(1-24) (synacthen 1 µg IV) test, and serum cortisol response was compared between inflicted (TBI(I) ) and accidental (TBI(A) ) groups. RESULTS: We assessed 64 children with TBI(I) and 134 with TBI(A) . Boys were more likely than girls to suffer accidental (P < 0·001), but not inflicted TBI. TBI(I) children displayed a 14% reduction in peak stimulated cortisol in comparison with the TBI(A) group (P < 0·001), as well as reduced cortisol responses at + 30 (P < 0·01) and + 60 min (P < 0·001). Importantly, these differences were not associated with severity of injury. The odds ratio of TBI(I) children having a mother who suffered domestic violence during pregnancy was 6·2 times that of the TBI(A) group (P < 0·001). However, reported domestic violence during pregnancy or placement of child in foster care did not appear to affect cortisol responses. CONCLUSION: Synacthen-stimulated cortisol response is attenuated following inflicted TBI in early childhood. This may reflect chronic exposure to environmental stress as opposed to pituitary injury or early-life programming.

Introduction of a Protocol for Structured Follow-Up and Texting of Inadequate and Borderline-Positive Newborn Metabolic Screening Results.

A national protocol for structured follow-up and texting of repeat newborn bloodspot screening (NBS) sample requests was introduced. Repeat samples are needed where the initial sample is inadequate or the result borderline-positive. This protocol aimed to improve the timeliness and completeness of receipt of repeat NBS samples. Under the structured protocol, all repeat sample requests were phoned or texted to the lead maternity carer (LMC), in addition to the standard written report issued. Weekly text reminders were sent until 4 weeks or the sample was received. National data were monitored following implementation of the protocol. The proportion of repeat samples received within 10 days of request improved after the introduction of the protocol, from 35.0% in 2013 to 81.4% in 2020 (p < 0.001). The proportion of requests lost to follow-up decreased, from 4.1% in 2013 to 1.3% in 2020 (p < 0.001). A structured NBS follow-up protocol that included SMS text messaging led to an earlier and more complete receipt of repeat samples. This is likely due to practitioners receiving the request more quickly, as well as the laboratory adopting a consistent approach to repeated reminders. SMS text messages are a useful adjunctive method for screening programmes to communicate with health care providers.

Introducing Newborn Screening for Severe Combined Immunodeficiency-The New Zealand Experience.

Screening for severe combined immunodeficiency (SCID) was added to the New Zealand national newborn screening programme in December 2017. Documentation pertaining to the application to add SCID to the panel and screening results over the first three years were reviewed. Screening evaluation metrics were shown to differ according to site of collection (babies in a neonatal intensive care unit vs. the community), definition of a positive test (out-of-range result vs. result leading to a further action on baby), and screening target/case definition (primary SCID vs. non-SCID T-cell lymphopenia). Our experience demonstrates both the value of close clinical involvement during the implementation phase of SCID screening and that the use of standard definitions will facilitate international comparison.

Evaluation of a New Laboratory Protocol for Newborn Screening for Congenital Adrenal Hyperplasia in New Zealand.

Between 2005 and 2021, 49 cases of classical congenital adrenal hyperplasia were diagnosed in New Zealand, 39 were detected in newborns and 10 were not detected by screening. Currently, for every case of CAH detected by screening, 10 false-positive tests are encountered. Second-tier liquid chromatography-tandem mass spectrometry (LCMSMS) has the potential to improve screening sensitivity and specificity. A new laboratory protocol for newborn screening for CAH was evaluated. Birthweight-adjusted thresholds for first- and second-tier 17-hydroxyprogesterone, second-tier 21-deoxycortisol and a steroid ratio were applied to 4 years of newborn screening data. The study was enriched with 35 newborn screening specimens from confirmed CAH cases. Newborn screening was conducted on 232,542 babies, and 11 cases of classical CAH were detected between 2018 and 2021. There were 98 false-positive tests (specificity 99.96%, PPV = 10.1%) using the existing protocol. Applying the new protocol, the same 11 cases were detected, and there were 13 false-positive tests (sensitivity > 99.99%, PPV = 45.8%, (X2 test p < 0.0001). Incorporating the retrospective specimens, screening sensitivity for classical CAH was 78% (existing protocol), compared to 87% for the new protocol (X2 test p = 0.1338). Implementation of LCMSMS as a second-tier test will improve newborn screening for classical CAH in New Zealand.

Hysterosalpingography with Oil-Soluble Contrast Medium Does Not Increase Newborn Hypothyroidism.

OBJECTIVE: Hysterosalpingography (HSG) with oil-soluble contrast medium (OSCM) improves pregnancy rates in women with idiopathic infertility. However, OSCM has high iodine content and slow clearance resulting in potential iodine excess. If pregnancy occurs, this could impact fetal thyroid gland development and function. We aim to determine the effect of a preconceptional OSCM HSG on the thyroid function of the neonate. Design and Patients. This was a retrospective analysis of newborn TSH data for a cohort of neonates conceived within six months of an OSCM HSG in the Auckland region, New Zealand, from the years 2000 to 2019. Thyroid-stimulating hormone (TSH) levels of these newborns were obtained from newborn screening, which is routinely performed for all children at 48-72 hours of life. The primary outcome was the incidence of permanent or transient congenital hypothyroidism in this cohort. RESULTS: Of 146 babies included, all had normal TSH levels with values ranging from 1 to 7 mIU/L on the whole blood analysis of a capillary heel sample using the Perkin-Elmer AutoDelfia assay. Conception during the first 3 cycles following an OSCM HSG was 76%; however, TSH levels in this group were not higher than those conceived in later cycles. CONCLUSION: Preconceptional OSCM HSG did not increase the risk of congenital hypothyroidism in the New Zealand scenario.

Newborn Screening for CAH-Challenges and Opportunities.

Newborn screening for congenital adrenal hyperplasia (CAH) using 17-hydroxyprogesterone (17-OHP) as an indicator of disease was first introduced in the 1970s [...].

Birth Weight- or Gestational Age-adjusted Second-tier LCMSMS Cutoffs Improve Newborn Screening for CAH in New Zealand.

CONTEXT: The positive predictive value of newborn screening for congenital adrenal hyperplasia (CAH) in New Zealand is approximately 10%. The use of a second tier liquid chromatography-tandem mass spectrometry bloodspot steroid profile test with birth weight- or gestational age-adjusted screening cutoffs may result in further screening improvements. METHODS: Three years of newborn screening data with additional second-tier steroid metabolites was evaluated (n = 167 672 births). Data from babies with a negative screening test and confirmed CAH cases were compared. First- and second-tier steroid measurements were correlated with both birth weight and gestational age. Analysis of variance was used to determine birth weight and gestational age groups. Screening cutoffs were determined and applied retrospectively to model screening performance. RESULTS: First-tier immunoassay data correlated better with gestational age than with birth weight, but there was no difference with second-tier steroid measurements. Four distinct birth weight and gestational age groups were established for 17-hydroxyprogesterone and a steroid ratio measurement. Application of 97.5th percentile second-tier birth weight- or gestational age-adjusted cutoffs would result in 10 positive tests over the period of the study with 8 true-positive screens and 2 false-positive tests. The positive predictive value of screening would be increased from 10.8% to 80%. CONCLUSIONS: The use of either birth weight- or gestational age-adjusted cutoffs for second-tier screening tests can significantly reduce the false positive rate of newborn screening for CAH in New Zealand without loss in screening sensitivity.

Randomized Controlled Trial Evaluating the Use of Zoledronic Acid in Duchenne Muscular Dystrophy.

CONTEXT: Patients with glucocorticoid-dependent Duchenne muscular dystrophy (DMD) have increased fracture risk and reduced bone mineral density (BMD), often precipitating mobility loss. OBJECTIVE: To investigate use of zoledronic acid (ZA) in DMD in improving BMD. METHODS: Two arm, parallel, randomized controlled trial, set in pediatric hospitals across Australia and New Zealand. Sixty-two (31 per arm) boys with glucocorticoid-dependent DMD between 6 and 16 years were included. Five ZA infusions (0.025 mg/kg at months 0, and 3, and 0.05 mg/kg at months 6, 12, and 18), plus calcium and vitamin D, were compared with calcium and vitamin D alone. The main outcome measures were change in lumbar spine (LS) BMD raw and Z-score by dual energy absorptiometry x-ray (DXA) at 12 and 24 months, secondary outcomes assessing mobility, fracture incidence, bone turnover, peripheral quantitative computerized (pQCT) and pain scores. RESULTS: At 12 and 24 months, mean difference in changes of LS BMD Z-score from baseline was 1.2 SD (95% CI 0.9-1.5), higher by 19.3% (14.6-24.0) and 1.4 SD (0.9-1.9), higher by 26.0% (17.4-34.5) in ZA than control arms respectively (both P < .001). Five controls developed Genant 3 vertebral fractures, 0 in the ZA arm. Mobility, pain, and bone turnover markers were similar between arms at 12 and 24 months. Trabecular BMC and vBMD pQCT at radius and tibia were greater at 12 months in the ZA cohort than control; the evidence for this difference remained at 24 months for radius but not tibia. CONCLUSION: ZA improved BMD in glucocorticoid-dependent DMD boys. Although the small cohort precluded demonstrable fracture benefit, improved BMD might reduce incident vertebral fracture.

It All Depends What You Count-The Importance of Definitions in Evaluation of CF Screening Performance.

Screening metrics are essential to both quality assessment and improvement, but are highly dependent on the way positive tests and cases are counted. In cystic fibrosis (CF) screening, key factors include how mild cases of late-presenting CF and CF screen positive, inconclusive diagnosis (CFSPID) are counted, whether those at prior increased risk of CF are excluded from the screened population, and which aspects of the screening pathway are considered. This paper draws on the New Zealand experience of almost forty years of newborn screening for CF. We demonstrate how different definitions impact the calculation of screening sensitivity. We suggest that, to enable meaningful comparison, CF screening reports should clarify what steps in the screening pathway are included in the assessment, as well as the algorithm used and screening target.

Newborn Screening for Congenital Adrenal Hyperplasia: Review of Factors Affecting Screening Accuracy.

Newborn screening for 21-hydroxylase deficiency (21OHD), the most common form of congenital adrenal hyperplasia, has been performed routinely in the United States and other countries for over 20 years. Screening provides the opportunity for early detection and treatment of patients with 21OHD, preventing salt-wasting crisis during the first weeks of life. However, current first-tier screening methodologies lack specificity, leading to a large number of false positive cases, and adequate sensitivity to detect all cases of classic 21OHD that would benefit from treatment. This review summarizes the pathology of 21OHD and also the key stages of fetal hypothalamic-pituitary-adrenal axis development and adrenal steroidogenesis that contribute to limitations in screening accuracy. Factors leading to both false positive and false negative results are highlighted, along with specimen collection best practices used by laboratories in the United States and worldwide. This comprehensive review provides context and insight into the limitations of newborn screening for 21OHD for laboratorians, primary care physicians, and endocrinologists.