Severe Congenital Hypothyroidism Research Articles

Knowns and unknowns about congenital hypothyroidism: 2022 update

Several excellent guidelines and expert opinions on congenital hypothyroidism (CH) are currently available. Nonetheless, these guidelines do not address several issues related to CH in detail. In this review, the authors chose the following seven clinical issues that they felt were especially deserving of closer scrutiny in the hope that drawing attention to them through discussion would help pediatric endocrinologists and promote further interest in the treatment of CH. 1. How high should the levothyroxine (L-T4) dose be for initial treatment of severe and permanent CH? 2. What is the optimal method for monitoring treatment of severe CH? 3. At what level does maternal iodine intake during pregnancy affect fetal and neonatal thyroid function? 4. Does serum thyroglobulin differ between patients with a dual oxidase 2 (DUOX2) variants and those with excess iodine? 5. Who qualifies for a genetic diagnosis? 6. What is the best index for distinguishing transient and permanent CH? 7. Is there any cancer risk associated with CH? The authors discussed these topics and jointly edited the manuscript to improve the understanding of CH and related issues.

Incidence of primary congenital hypothyroidism over 24 years in Finland

BackgroundA rise in the incidence of congenital hypothyroidism (CH) has been reported worldwide. This nationwide study aimed to describe the secular trends and current incidence of CH in Finland.MethodsTwo independent study cohorts, a national and a regional, were collected from national registers and patient records. The national cohort represents all CH cases born in Finland between 1994 and 2017. Birth data, results of the screening test, and the incidence of CH were reviewed.ResultsBetween 1994 and 2017, 1,400,028 children were born in Finland. Of these children, 503 were diagnosed with primary CH (incidence 1:2783). Male-to-female sex ratio was 1:2.0. The nationwide incidence was 33 cases per 100,000 live births between 1994 and 1999, 38 cases per 100,000 live births between 2000 and 2005, 40 cases per 100,000 live births between 2006 and 2011, and 33 cases per 100,000 live births between 2012 and 2017. In the regional cohort (n = 139), the incidence of transient CH was 3.6%. The incidence of mild, moderate, and severe CH remained constant.ConclusionsIn Finland, the incidence of CH has not changed during the 24-year study period.ImpactAs opposed to recent reports worldwide, the incidence of congenital hypothyroidism has not changed between 1994 and 2017 in Finland.The proportions of mild, moderate, and severe congenital hypothyroidism did not change significantly over the study period.Lowering the TSH cut-off limit or increasing immigration did not affect the incidence rate of primary congenital hypothyroidism in Finland.

An Intramolecular Ionic Interaction Linking Defective Sodium/Iodide Symporter Transport to the Plasma Membrane and Dyshormonogenic Congenital Hypothyroidism.

Background: The sodium/iodide symporter (NIS) mediates active iodide accumulation in the thyroid follicular cell. Autosomal recessive iodide transport defect (ITD)-causing loss-of-function NIS variants lead to dyshormonogenic congenital hypothyroidism due to deficient iodide accumulation for thyroid hormonogenesis. Here, we aimed to identify, and if so to functionally characterize, novel ITD-causing NIS pathogenic variants in a patient diagnosed with severe dyshormonogenic congenital hypothyroidism due to a defect in iodide accumulation in the thyroid follicular cell, as suggested by nondetectable radioiodide accumulation in a normally located thyroid gland, as well as in salivary glands. Methods: The proposita NIS-coding SLC5A5 gene was sequenced using Sanger sequencing. In silico analysis and functional in vitro characterization of the novel NIS variants were performed. Results: Sanger sequencing revealed novel compound heterozygous SLC5A5 gene variants (c.970-3C>A and c.1106A>T, p.D369V). In silico analysis suggested that c.970-3C>A disrupts the canonical splice acceptor site located in intron 7. Splicing minigene reporter assay revealed that c.970-3C>A causes exon 8 skipping during NIS pre-mRNA splicing leading to the NIS pathogenic variant p.Y324Hfs*148. Moreover, in silico analysis indicated p.D369V as pathogenic. Functional in vitro studies demonstrated that p.D369V NIS does not mediate iodide accumulation, as p.D369V causes NIS to be retained in the endoplasmic reticulum. Mechanistically, we propose an intramolecular ionic interaction involving the β carboxyl group of D369 and the guanidinium group of R130, located in transmembrane segment 4. Of note, an Asp residue at position 369-which is highly conserved in SLC5A family members-is required for functional NIS expression at the plasma membrane. Conclusions: We uncovered a critical intramolecular interaction between R130 and D369 required for NIS maturation and plasma membrane expression. Moreover, we identified the first intronic variant causing aberrant NIS pre-mRNA splicing, thus expanding the mutational landscape in the SLC5A5 gene leading to dyshormonogenic congenital hypothyroidism.

Basal Serum Thyroxine Level should Guide Initial Thyroxine Replacement Dose in Neonates with Congenital Hypothyroidism

Objective:Initial high-dose sodium levothyroxine (Na-LT4) (10-15 μg/kg/day) replacement for primary congenital hypothyroidism (CH) is recommended in guidelines. However, high-dose Na-LT4 risks iatrogenic hyperthyroidism. The aim of this study was to investigate the normalizing effect of varying initial doses of Na-LT4 on serum thyroid hormone levels.Methods:Fifty-two patients were analyzed retrospectively. The patients were classified into mild (27/51.9%), moderate (11/21.1%) and severe (14/26.9%) CH, based on initial free thyroxine (fT4) levels. Time taken to achieve target hormone levels was compared within groups.Results:Initial mean Na-LT4 doses for mild, moderate and severe disease were 6.9±3.3, 9.4±2.2 and 10.2±2 μg/kg/day. Serum fT4 levels reached the upper half of normal range (>1.32 ng/dL) in a median of 16, 13 and 16 days in patients with mild, moderate and severe CH with the mean time from initial treatment to first control visit of 14.8±6 days (range 1-36). There was no significant difference in terms of time to achieve target fT4 hormone levels according to disease severity (p=0.478). Seven (25.9%), eight (72.7%) and eight (57.1%) patients experienced hyperthyroxinemia (serum fT4 >1.94 ng/dL) in the mild, moderate, and severe CH groups at the first visit, respectively (p=0.016).Conclusion:Not all patients diagnosed with CH require high-dose Na-LT4. Initial dose of Na-LT4 may be selected on the basis of pretreatment thyroid hormone levels. Some patients with moderate and severe CH, experienced iatrogenic hyperthyroxinemia even though the dose was close to the lower limit of the recommended range in guidelines. We suggest that lower initial doses may be appropriate with closer follow-up within the first week.

MON-102 Serum Concentrations of FT4 and TSH in the First Six Months of L-Thyroxine Treatment in Infants with Congenital Hypothyroidism: Target Attainment Rates Should Be Improved

Levo-Thyroxine (L-T4) is the medication of choice for treating congenital hypothyroidism (CH). Adequate L-T4 treatment is essential for early neurodevelopment in affected patients. Both under- and overtreatment with L-T4 were associated with long-term adverse neurological outcomes. Based on clinical experience, initial L-T4 dosing does not always result in optimal TSH and FT4 concentrations in all CH patients. The purposes of this study were 1) to quantify FT4 and TSH target attainment rates (TAR) in the first six months of L-T4 treatment in infants with CH, 2) to compare characteristics of patients with FT4 concentrations “OUT of” versus “IN” the target range at first time of monitoring.A multicenter retrospective analysis was conducted in infants born between 1995 and 2018. TSH and FT4 TARs were defined according to the most recent guidelines of the European Society for Paediatric Endocrinology (ESPE), as the percentage of concentrations “in” and “in the upper half” of the corresponding laboratory age-specific reference range for TSH and FT4, respectively.We analyzed a total of 208 TSH and 186 FT4 serum concentrations from 60 patients during the first 6 months of L-T4 treatment. The pretreatment FT4 and TSH serum concentrations (mean±SD) were 8.3±5.7 pmol/L and 338±248 mU/L, respectively. CH severity according to ESPE guidelines was severe, moderate and mild for 32%, 27% and 32% of the patients. Postnatal age (PNA) (mean±SD) at start of treatment was 10±12 days. Starting dose of L-T4 (mean±SD) for severe, moderate and mild CH were 10±4, 10±3, and 7±4 µg/kg/day, respectively. Over the study period, TSH TARs of 63% did not further improve between the first monitoring (mean at 17 days of treatment) and fourth monitoring (mean at 4 months of treatment), while FT4 TARs increased from 22% to 45% paralleled with a decrease of too high FT4 values from 55% to 21%.Comparing patients with FT4 concentrations “OUT of” versus “IN” the target range at first time monitoring (16 versus 18 days after starting treatment; p=0.45), they did not differ in pretreatment FT4 concentrations (p=0.2). In contrast, patients who had FT4 concentrations “OUT of” versus “IN” the target range received first dose of L-T4 at an earlier median PNA (7 versus 16 days; p=0.008), had higher pretreatment mean TSH concentrations (364 versus 181 mU/L; p=0.02) and received a higher mean initial L-T4 dose (10.3 versus 7.1 µg/kg/day; p=0.01).First, our results show that FT4 and TSH target ranges were not reached in all patients in the first six months of treatment. Second, our data suggest that TARs could be improved by individualizing initial L-T4 dosing not only according to pretreatment FT4 but also to pretreatment TSH concentrations. L-T4 dosing optimization is needed in this population.

The TPO mutation screening and genotype-phenotype analysis in 230 Chinese patients with congenital hypothyroidism

Inborn defects in thyroid hormone biosynthesis contribute to nearly half of congenital hypothyroidism (CH) cases in China. The thyroid peroxidase (TPO) mutation is one of the most frequent mutations that results in thyroid dyshormonogenesis. In this study, 35 non-synonymous mutations in 15 TPO sites, including 6 novel mutations, were identified in 230 Chinese patients with CH. The enzyme activity of the mutations in TPO was investigated in vitro, and patients with less than 15% residual enzyme activity showed severe CH, such as markedly increased thyroid-stimulating hormone (TSH) at diagnosis (>100 μIU/mL) and pronounced goiter, and required a higher dose of L-thyroxine to maintain the euthyroid. However, CH patients with greater than 16% TPO activity showed mild CH, a typical childhood socially without L-thyroxine treatment before 3 years of age, and the appearance of a macroscopic goiter at childhood. The findings indicated that the residual enzymatic activity of TPO was correlated with clinical phenotypes of CH patients with TPO biallelic mutations.

Follow-up of infants with congenital hypothyroidism and low total thyroxine/thyroid stimulating hormone on newborn screen.

PurposeNewborn screening (NBS) methods to detect congenital hypothyroidism (CH) vary regarding whether total thyroxine (T4), thyroid stimulating hormone (TSH), or both are measured. Neonates with low T4 and normal or low TSH (lowT4/TSH) may only be detected by T4-inclusive methods or age-dependent repeat screens. Premature neonates and those with pituitary-hypothalamic disorders frequently manifest lowT4/TSH.MethodsThis is a retrospective case-study of newborns who were screen-positive for lowT4/TSH in Alabama in 2009–2016 using a combined T4 and TSH method and 2 routine NBS. The clinical, laboratory, and final diagnosis after 3 years were determined.ResultsOver 8 years, 225 infants were referred to our institution for evaluation and treatment of CH. Twelve infants were screen-positive for lowT4/TSH by first or second NBS. Four of the 12 infants had permanent CH (30%): 2 with primary and 2 with central etiologies. One infant with moderately severe central CH was only detected by the routine second NBS. Six of 7 premature infants had elevated TSH on serum confirmation labs consistent with a delay in hypothalamic-pituitary maturation, yet 2 of these patients were later established to have permanent primary CH. While most cases of lowT4/TSH resolved by 3 years of age, several neonates had extended periods of moderate to severe hypothyroxinemia prior to detection and treatment.ConclusionsOne third of the infants with lowT4/TSH on NBS in this study had permanent CH. These results emphasize the importance of T4-based assay methods, subsequent (repeat) screens and long-term follow-up in the management of neonates with lowT4/TSH on newborn screen.

Adrenal Steroids in Female Hypothyroid Neonates: Unraveling an Association Between Thyroid Hormones and Adrenal Remodeling.

The adrenal gland undergoes substantial remodeling during the neonatal period, an essential developmental process that remains incompletely understood. With respect to control over the remodeling process and, specifically, the role of thyroid hormones (THs), no human studies have been published. The effects of both hypo- and hyperthyroidism have only been evaluated in adults, focusing on the mature adrenal. Recent studies have identified expression of the TH receptor β1 in the mouse adrenal X-zone and have demonstrated that TH administration could alter the postnatal adrenal remodeling process. To address whether THs influence adrenal steroid profiles and adrenal remodeling during the neonatal period. We compared the adrenal steroid profile of a naturally occurring prototype, female neonates with severe congenital hypothyroidism (CH) (n = 22, upon diagnosis of CH), with that of euthyroid neonates (n = 20). Significantly higher levels of adrenal steroids (17-OH-progesterone, dehydroepiandrosterone sulfate, Δ4-androstenedione, and testosterone) were measured in neonates with severe CH compared with euthyroid neonates and returned to within normal range after euthyroid state had been established on l-thyroxine replacement therapy, whereas cortisol levels did not differ. TSH values in the CH group were positively correlated with circulating adrenal steroids, whereas free T4 levels were negatively correlated with circulating adrenal steroids. The hormonal profile of female neonates with severe CH suggests a more active adrenal fetal zone compared with control subjects. These data indirectly associate THs with the adrenal remodeling and maturation process in humans. Based on our results, we suggest that severe hypothyroidism decelerates the involution of the adrenal fetal zone that normally occurs postnatally.

White matter microstructural abnormalities in children with severe congenital hypothyroidism.

This study assessed white matter microstructural integrity and behavioral correlates for children with severe congenital hypothyroidism (CH) who were identified and treated early following newborn screening. Eighteen children with severe CH and 21 healthy controls underwent a battery of behavioral measures of hearing, language and communication, along with diffusion MR imaging. Tract-based spatial statistics were performed on standard diffusion parameters of fractional anisotropy and diffusivity metrics. Microscopic diffusion anisotropy mapping based on the Spherical Mean Technique was also used to evaluate biologically specific metrics. Compared with age-matched controls, children with severe CH had poorer hearing and communication skills, albeit generally within normal limits. Children with severe CH had fractional anisotropy that was significantly lower in the cerebellum, bilateral thalami and right temporal lobe, and radial diffusivity that was significantly higher in the cerebellum and bilateral thalami. Microscopic fractional anisotropy and intra-neurite volume fraction were also significantly decreased, and transverse microscopic diffusivity was significantly increased, in the CH group in areas including the cerebellum, thalamus, occipital lobe, and corpus callosum, and in the white matter adjacent to sensorimotor cortex, particularly in the left hemisphere. Significant and widespread correlations were observed between behavioral measures and measures of white matter microstructural integrity in children with CH. The results indicate that children with severe CH who are identified through newborn screening may have significant brain white matter microstructural abnormalities despite early treatment.

An exonic splicing enhancer mutation in DUOX2 causes aberrant alternative splicing and severe congenital hypothyroidism in Bama pigs.

ABSTRACTPigs share many similarities with humans in terms of anatomy, physiology and genetics, and have long been recognized as important experimental animals in biomedical research. Using an N-ethyl-N-nitrosourea (ENU) mutagenesis screen, we previously identified a large number of pig mutants, which could be further established as human disease models. However, the identification of causative mutations in large animals with great heterogeneity remains a challenging endeavor. Here, we select one pig mutant, showing congenital nude skin and thyroid deficiency in a recessive inheritance pattern. We were able to efficiently map the causative mutation using family-based genome-wide association studies combined with whole-exome sequencing and a small sample size. A loss-of-function variant (c.1226 A>G) that resulted in a highly conserved amino acid substitution (D409G) was identified in the DUOX2 gene. This mutation, located within an exonic splicing enhancer motif, caused aberrant splicing of DUOX2 transcripts and resulted in lower H2O2 production, which might cause a severe defect in thyroid hormone production. Our findings suggest that exome sequencing is an efficient way to map causative mutations and that DUOX2D409G/D409G mutant pigs could be a potential large animal model for human congenital hypothyroidism.

Relation between Early Over- and Undertreatment and Behavioural Problems in Preadolescent Children with Congenital Hypothyroidism

Objective: Congenital hypothyroidism (CH) per se, when not treated or undertreated, may lead to severe behavioural problems (cretinism), whereas overtreatment of CH seems associated with attention problems. Design and Methods: For 55 CH patients, prospectively followed from birth until 11 years, parents rated the Child Behaviour Checklist and teachers the Teacher’s Report Form at children’s ages 6 and 11 years. We related scores regarding Attention, Delinquency, and Aggression (ADA scores, indicative for attention deficit hyperactivity syndrome, ADHD), and scores regarding Withdrawn, Anxious, Social, and Thought problems (WAST scores, indicative for autism) to the occurrence of over- and undertreatment in five age periods. Over- and undertreatment were defined as free thyroxine (fT₄) concentrations above/below the range of the patient’s individual fT₄ steady state concentration. Results: ADA scores at 6 and 11 years for patients overtreated in the period 1–3 months postnatally were higher than those for patients who were not overtreated. Patients with severe CH undertreated in the period 3–6 months postnatally had higher WAST scores at 6 and 11 years than all other patients. Conclusions: This is the first study suggesting that permanent ADHD as well as autism in CH patients at ages 6 and 11 years are the result of early overtreatment and undertreatment, respectively.

Optimal Timing of Repeat Newborn Screening for Congenital Hypothyroidism in Preterm Infants to Detect Delayed Thyroid-Stimulating Hormone Elevation

To evaluate the timing of a delayed rise in thyroid-stimulating hormone (TSH) levels in preterm infants with congenital hypothyroidism, and to determine whether cases of congenital hypothyroidism would be missed by using current consensus guidelines of repeat screening at approximately 2 weeks of age or 2 weeks after the first screening. The study was performed over a 13-year period (January 2004-December 2016). Whole-blood TSH samples were collected between 72 and 120 hours after birth. Repeat samples were collected weekly in preterm infants until the infant was term-corrected (37 weeks' gestation). Patients were followed up to determine whether congenital hypothyroidism was permanent or transient. Twenty-seven (50.9%) preterm infants born at <33 weeks of gestation who were diagnosed with congenital hypothyroidism had delayed TSH elevation and would not have been detected on first newborn screen. Twelve of these infants (40.7%) with delayed TSH elevation had decompensated hypothyroidism at diagnosis (free thyroxine [FT4] <10 pmol/L), and 4 had severe congenital hypothyroidism (FT4 <5.5 pmol/L) at diagnosis. If screening had been repeated only at 2 weeks of life, 13 infants (48%) with delayed TSH elevation would not have been identified. Of the 27 infants with delayed TSH elevation, 6 (22%) have permanent congenital hypothyroidism, and another 12 will be reevaluated at age 3 years. Repeat screening for congenital hypothyroidism in preterm infants is necessary to avoid missing cases of congenital hypothyroidism with delayed TSH elevation. Repeat screening once at 2 weeks of life will miss infants with delayed TSH elevation and decompensated permanent congenital hypothyroidism.

High frequency of mutations in 'dyshormonogenesis genes' in severe congenital hypothyroidism.

ObjectiveResults of the screening of disease causative mutations in congenital hypothyroidism (CH) vary significantly, depending on the sequence strategy, patients’ inclusion criteria and bioinformatics. The objective was to study the molecular basis of severe congenital hypothyroidism, using the next generation sequencing (NGS) and the recent guidelines for assessment of sequence variants.Design243 patients with CH (TSH levels at neonatal screening or retesting greater than 90 mU/l) and 56 control subjects were included in the study.MethodsA custom NGS panel targeting 12 CH causative genes was used for sequencing. The sequence variants were rated according to American College of Medical Genetics and Genomics (ACMG) guidelines.ResultsIn total, 48 pathogenic, 7 likely pathogenic and 57 variants of uncertain significance were identified in 92/243 patients (37.9%), while 4 variants of uncertain significance were found in 4/56 control subjects (7.1%). 13.1% (12/92) of the cases showed variants in ‘thyroid dysgenesis’ (TD) genes: TSHR, n = 6; NKX2-1, n = 2; NKX2-5, n = 1; PAX8, n = 3. The variants in ‘dyshormonogenesis’ (DH) genes were found in 84.8% (78/92) of cases: TPO, n = 30; DUOX2, n = 24; TG, n = 8; SLC5A5, n = 3; SLC26A4, n = 6; IYD, n = 1. 8 patients showed oligonenic variants. The majority of variants identified in DH genes were monoallelic.ConclusionsIn contrast to earlier studies demonstrating the predominance of TD in severe CH, the majority of variants identified in our study were in DH genes. A large proportion of monoallelic variants detected among DH genes suggests that non-mendelian mechanisms may play a role in the development of CH.

Mean high-dose L-thyroxine treatment is efficient and safe to achieve a normal IQ in young adult patients with congenital hypothyroidism

Context The optimal levothyroxine (LT4) dose to treat congenital hypothyroidism (CH) remains unclear, with debate over whether higher starting doses (>10 µg/kg) are necessary and safe for a normal intelligence quotient (IQ). Objective To examine psychomotor, metabolic, and quality of life (QoL) outcomes in patients with CH treated with a mean high initial LT4 dose. Design, settings, participants A cross-sectional cohort study of patients with CH identified in the Berlin newborn screening program from 1979 to 2003; 76 patients with CH (mean age, 18 years; mean initial LT4 dose, 13.5 µg/kg) and 40 siblings completed the study. Main outcome measures Psychomotor (Wechsler Intelligence Test, CNS Vital Signs), QoL (short form-36 Health Survey), anthropometric (body mass index, height), and metabolic (intima media thickness, laboratory parameters) outcomes were compared with those of healthy siblings. Mean values and percentage of episodes of elevated thyroxine (T4) and tri-jod-thyronin (T3) and suppressed thyrotropin (TSH) before age 2 years were analyzed. A meta-analysis of CH treatment studies was performed. Results There were no significant differences in IQ, QoL, or other outcome measures in patients with CH compared with controls. Most T4 levels were high before age 2 years and during subsequent testing, but mean T3 and TSH levels remained normal. The meta-analysis showed a significant IQ difference in severe vs mild CH cases only when treatment started with an LT4 dose Conclusions High initial LT4 dosing was effective and safely achieved optimal cognitive development in patients with CH, including those severely affected. Supranormal T4 values during infancy were not associated with impaired IQ in adolescence.

Study of molecular basis of thyroid dysgenesis

Congenital hypothyroidism is a heterogeneous group of diseases, which is manifested by loss of function of the thyroid gland that affects infants from birth. 80–85% of cases are due to different types of thyroid dysgenesis. 5 genes have been described that are involved in the pathogenesis of thyroid dysgenesis: TSHR, PAX8, FOXE1, NKX2-1, NKX2-5.&#x0D; Aims. To evaluate the prevalence of mutations in the genes TSHR, PAX8, FOXE1, NKX2-1, NKX2-5 among patients with severe congenital hypothyroidism.&#x0D; Materials and methods. 161 patients (64 boys, 97 girls) with congenital hypothyroidism (TSH levels at neonatal screening or retesting greater than 90 mU/l) were included in the study. 138 subjects had different variants of thyroid dysgenesis, and 23 patients had normal volume of the gland. A next generation sequencing was used for molecular-genetic analysis. Sequencing was performed using PGM semiconductor sequencer (Ion Torrent, Life Technologies, USA) and a panel “Hypothyroidism” (Custom DNA Panel). Assessment of the pathogenicity of sequence variants were carried out according to the latest international guidelines (ACMG, 2015).&#x0D; Results. 13 patients had variants in thyroid dysgenesis genes (8,1%, 13/161): TSHR, n = 6; NKX2-1, n = 3; NKX2-5, n = 1; PAX8, n = 3; FOXE1, n = 0.&#x0D; Conclusions. Mutations in thyroid dysgenesis genes are a rare pathology. The majority of variants among our patients were identified in TSHR.

The etiologies and incidences of congenital hypothyroidism before and after neonatal TSH screening program implementation: a study in southern Thailand.

Congenital hypothyroidism (CH) is one of the common causes of intellectual disability which can be prevented by early detection of an elevated thyroid stimulating hormone (TSH) level in the newborn and by treatment with thyroxine. In Thailand, neonatal TSH screening was implemented nationwide in 2005. The objective of the study was to determine the etiologies and the estimated incidences of CH in southern Thailand before and after the implementation of a neonatal TSH screening program in 2005. The medical records of pediatric patients who were diagnosed with primary CH at Songklanagarind Hospital during 1995-2013 were retrospectively reviewed. The study was divided into two time periods: study period 1 (SP1) (1995-2004) and study period 2 (SP2) (2005-2013), the time before and after TSH program implementation. The most common form of CH during SP1 was overt permanent CH (66%), mostly caused by athyreosis or ectopic thyroid. In SP2, the most common form of CH was mild permanent CH (39%) (mostly due to dyshormonogenesis), followed by overt CH (32%) and transient CH (29%). The overall annual estimated incidence of CH per 10,000 live births in Songkhla Province was 1.69 (1:5021) in SP1, increasing to 4.77 (1:2238) in SP2; in all 14 provinces in southern Thailand, the estimated incidence was 1.24 (1:8094) in SP1 and 2.33 (1:4274) in SP2. Neonatal TSH screening has a significant impact on the increased detection of the mild form of permanent and transient CH cases, which may be important for the prevention of brain damage from less severe CH although this remains to be documented.

Mean High-Dose l-Thyroxine Treatment Is Efficient and Safe to Achieve a Normal IQ in Young Adult Patients With Congenital Hypothyroidism.

The optimal levothyroxine (LT4) dose to treat congenital hypothyroidism (CH) remains unclear, with debate over whether higher starting doses (>10 µg/kg) are necessary and safe for a normal intelligence quotient (IQ). To examine psychomotor, metabolic, and quality of life (QoL) outcomes in patients with CH treated with a mean high initial LT4 dose. A cross-sectional cohort study of patients with CH identified in the Berlin newborn screening program from 1979 to 2003; 76 patients with CH (mean age, 18 years; mean initial LT4 dose, 13.5 µg/kg) and 40 siblings completed the study. Psychomotor (Wechsler Intelligence Test, CNS Vital Signs), QoL (short form-36 Health Survey), anthropometric (body mass index, height), and metabolic (intima media thickness, laboratory parameters) outcomes were compared with those of healthy siblings. Mean values and percentage of episodes of elevated thyroxine (T4) and tri-jod-thyronin (T3) and suppressed thyrotropin (TSH) before age 2 years were analyzed. A meta-analysis of CH treatment studies was performed. There were no significant differences in IQ, QoL, or other outcome measures in patients with CH compared with controls. Most T4 levels were high before age 2 years and during subsequent testing, but mean T3 and TSH levels remained normal. The meta-analysis showed a significant IQ difference in severe vs mild CH cases only when treatment started with an LT4 dose <10 µg/kg. High initial LT4 dosing was effective and safely achieved optimal cognitive development in patients with CH, including those severely affected. Supranormal T4 values during infancy were not associated with impaired IQ in adolescence.

Neurodevelopmental assessment of neonates with congenital hypothyroidism in a tertiary care center

Background: Thyroid hormones play a crucial role in early neurodevelopment so that untreated severe congenital hypothyroidism (CH) results in neurological and psychiatric deficits, including intellectual disability, spasticity, and disturbances of gait and coordination. Objective: The aim of this study is to assess the neuromotor and neurocognitive development of babies at 12 months of age who are diagnosed to have CH and initiated on thyroxine treatment at birth. Furthermore, to estimate the occurrence of CH among babies delivered in our hospital through thyroid screening. Study Design: This was a descriptive study. Setting: The study was conducted in Sree Gokulam Medical College Hospital and Research Foundation, a tertiary care center, located in Trivandrum, Kerala. Participants: All babies delivered in the hospital during the study period and neonatal screening was done for CH. Methods: Cord blood was collected as the direct flow of blood from cord, labeled and sent to laboratory from delivery room for analysis (by chemiluminescent assay) of thyroid-stimulating hormone (TSH). Babies with cord blood TSH level ?20 uIU/ml were repeated at 72 h of age for venous TSH and FT4 level. Venous TSH level ?20 uIU/ml with low FT4 (below normal range for age) was considered as abnormal and initiated on treatment before discharge from the hospital. These babies were followed till 12 months of age for neurodevelopmental assessment. Results: The occurrence of CH among babies delivered in our hospital was 0.6 in 100 live births. Neurodevelopmental assessment of babies with CH on follow-up has shown normal neuromotor and neurocognition at 12 months of age with early detection and prompt initiation of L-thyroxine at a higher dose range within 5 days of age. Conclusion: In our study, early detection and initiation of treatment in infants with CH have shown normal neuromotor and neurocognitive development at 12 months of age.

Are lower TSH cutoffs in neonatal screening for congenital hypothyroidism warranted?

When newborn screening (NBS) for congenital hypothyroidism (CH) using thyroid-stimulating hormone (TSH) as a primary screening test was introduced, typical TSH screening cutoffs were 20-50 U/L of whole blood. Over the years, lowering of TSH cutoffs has contributed to an increased prevalence of detected CH. However, a consensus on the benefit deriving from lowering TSH cutoffs at screening is lacking. The present paper outlines arguments both for and against the lowering of TSH cutoffs at NBS. It includes a review of recently published evidence from Australia, Belgium and Italy. A section focused on economic implications of lowering TSH cutoffs is also provided. One issue that bears further examination is the extent to which mild iodine deficiency at the population level might affect the association of neonatal TSH values with cognitive and developmental outcomes. A debate on TSH cutoffs provides the opportunity to reflect on how to make NBS for CH more effective and to guarantee optimum neurocognitive development and a good quality of life to babies with mild as well as with severe CH. All authors of this debate article agree on the need to establish optimal TSH cutoffs for screening programs in various settings and to ensure the benefits of screening and access to care for newborns worldwide.

Digenic DUOX1 and DUOX2 Mutations in Cases With Congenital Hypothyroidism.

Context:The DUOX2 enzyme generates hydrogen peroxide (H2O2), a crucial electron acceptor for the thyroid peroxidase–catalyzed iodination and coupling reactions mediating thyroid hormone biosynthesis. DUOX2 mutations result in dyshormonogenetic congenital hypothyroidism (CH) that may be phenotypically heterogeneous, leading to the hypothesis that CH severity may be influenced by environmental factors (e.g., dietary iodine) and oligogenic modifiers (e.g., variants in the homologous reduced form of NAD phosphate-oxidase DUOX1). However, loss-of-function mutations in DUOX1 have not hitherto been described, and its role in thyroid biology remains undefined.Case Description:We previously described a Proband and her brother (P1, P2) with unusually severe CH associated with a DUOX2 homozygous nonsense mutation (p.R434*); P1, P2: thyrotropin >100 µU/mL [reference range (RR) 0.5 to 6.3]; and P1: free T4 (FT4) <0.09 ng/dL (RR 0.9 to 2.3). Subsequent studies have revealed a homozygous DUOX1 mutation (c.1823-1G>C) resulting in aberrant splicing and a protein truncation (p.Val607Aspfs*43), which segregates with CH in this kindred.Conclusion:This is a report of digenic mutations in DUOX1 and DUOX2 in association with CH, and we hypothesize that the inability of DUOX1 to compensate for DUOX2 deficiency in this kindred may underlie the severe CH phenotype. Our studies provide evidence for a digenic basis for CH and support the notion that oligogenicity as well as environmental modulators may underlie phenotypic variability in genetically ascertained CH.