Congenital hypothyroidism: a clinical update of long-term outcome in young adults

Quality of life and socioeconomic and educational status in patients with congenital hypothyroidism

BACKGROUND

The aim of this study was to investigate the influence of primary congenital hypothyroidism (CH) on quality of life, level of education and socioeconomic status (SES).

METHODS

Two independent study cohorts, a national and a regional, were collected from Finnish national registers and patient records. Data on social security benefits, SES, marital status, and education were collected from Statistics Finland. Health-related quality of life (HRQoL) was studied in the regional patient cohort with the standardized 15D and 16D instruments.

RESULTS

There were no statistically significant differences in education level, marital status, or SES between CH patients (n = 40) and their matched controls at the age of 25 years. The mean 15D score was both statistically significantly and clinically importantly lower in CH patients (n = 29) than controls (0.904 vs. 0.953, p = 0.008). CH patients reported significantly lower scores across various dimensions of physical and mental HRQoL, including breathing, sleeping, speech, excretion, mental function, distress, and vitality. The mean 16D score was lower in CH patients compared to controls (0.917, vs. 0.947), but without statistical significance.

CONCLUSION

SES of CH patients did not differ from matched controls. Thus, most CH patients integrate well into society, but their HRQoL is impaired.

IMPACT

Most patients with primary congenital hypothyroidism integrate well into society. In the current study, their socioeconomic and marital status did not differ from matched controls at the age of 25 years. However, health-related quality of life measured using 15D instrument was impaired. Every fourth patient reported that congenital hypothyroidism influenced everyday life.

Comorbidity in Congenital Hypothyroidism-A Nationwide, Population-based Cohort Study

CONTEXT

Patients with congenital hypothyroidism (CH) are affected more often than the general population by other chronic diseases and neurological difficulties.

OBJECTIVE

The aim of this nationwide population-based register study was to investigate the incidence of congenital malformations, comorbidities, and the use of prescribed drugs in patients with primary CH.

METHODS

The study cohort and matched controls were identified from national population-based registers in Finland. All diagnoses from birth until the end of 2018 were collected from the Care Register, and subject-specific prescription drug purchases were identified from The Prescription Register from birth until the end of 2017.

RESULTS

Diagnoses of neonatal and chronic diseases were collected for 438 full-term patients and 835 controls (median follow-up time 11.6 years; range, 0-23 years). Newborns with CH were more often found to have neonatal jaundice (11.2% and 2.0%; P < .001), hypoglycemia (8.9% and 2.8%; P < .001), metabolic acidemia (3.2% and 1.1%; P = .007), and respiratory distress (3.9% and 1.3%; P < .003) as compared to their matched controls.Congenital malformations were diagnosed in 66 of 438 (15.1%) CH patients and in 62 of 835 (7.4%) controls (P < .001). The most commonly affected extrathyroidal systems were the circulatory and musculoskeletal systems. The cumulative incidence of hearing loss and specific developmental disorders was higher among CH patients than controls. The use of antidepressant and antipsychotic drugs was similar in CH patients and their controls.

CONCLUSION

CH patients have more neonatal morbidity and congenital malformations than their matched controls. The cumulative incidence of neurological disorders is higher in CH patients. However, our results do not support the existence of severe psychiatric comorbidity.

Thyroid function and long-term outcomes of children born to mothers with Graves' disease: A 20-year review

AIM

Thyroid dysfunction in infants born to mothers with Graves' disease (GD) is influenced by maternal factors including thyroid status, thyroid-stimulating hormone (TSH) receptor antibody (TRAb) concentration and antithyroid drug use. Thyroid dysfunction during early life could affect growth and development later in life. The aim of this study is to evaluate thyroid function tests (TFTs), and long-term growth and development of children born to mothers with GD.

METHODS

A retrospective chart review of children born to mothers with GD at the Faculty of Medicine Ramathibodi Hospital, Mahidol University, between January 2000 and December 2019 was performed. Clinical data including age of children at enrolment, sex, gestational age, birthweight, maternal thyroid status, maternal TRAb level, maternal GD treatment during pregnancy, neonatal TSH screening and TFT results, and growth and development outcomes of children were collected.

RESULTS

There were 262 children (148 males) enrolled. Twelve (4%) infants had neonatal GD. Five (2%) infants had hypothyroidism requiring levothyroxine treatment: four had secondary hypothyroidism and one patient had congenital primary hypothyroidism. Seven (3%) infants had transient TSH elevation, which fell to normal by 2 weeks of age. The remaining 238 children had normal TFT results. Three out of 12 children with neonatal GD had either delayed growth or development.

CONCLUSIONS

A number of infants born to mothers with GD had abnormal TFTs requiring specific management, and some of them had abnormal growth and development. Careful evaluation of TFTs and long-term follow-up are mandatory for those children.

Clinical survey of current practice regarding treatment of children with borderline thyroid abnormalities

AIM

Recently, there has been debate about reducing newborn screening (NBS) thyroid-stimulating hormone (TSH) cut-offs to identify children with mild, but potentially clinically significant, thyroid deficiency. Once identified by NBS, these children will be referred to paediatric endocrinologists for further testing and possible treatment; however, variation in current clinical practice is not known. The aim of this study is to survey Paediatric Endocrinologists in Australia and New Zealand to gain insight into clinical practice for the treatment of mild thyroid deficiency.

METHODS

A piloted questionnaire was sent to members of the Australasian Paediatric Endocrinologist Group. The survey asked the Australasian Paediatric Endocrinologist Group members about the investigations performed, treatment and follow-up for infants with different confirmatory serum TSH levels.

RESULTS

There were 42 completed surveys, a response rate of 34%. When presented with four case studies, 7% of clinicians would treat a child with confirmatory serum TSH of 8.7 mU/L with thyroxine, 69% would treat a child with confirmatory serum TSH 21.4 mU/L, 76% would treat a child with confirmatory serum TSH 24.3 mU/L and 95% would treat a child with confirmatory serum TSH 44.7 mU/L.

CONCLUSION

This contemporary survey of clinicians regarding the treatment of mild thyroid deficiency in children has shown that clinical practice varies extensively. International and national guidelines on the treatment of congenital hypothyroidism should be updated to incorporate new evidence and ensure consistency across clinical practice.

Fetal and Neonatal Thyroid Dysfunction

Fetal and neonatal dysfunctions include rare serious disorders involving abnormal thyroid function during the second half of gestation, which may persist throughout life, as for most congenital thyroid disorders, or be transient, resolving in the first few weeks of life, as in autoimmune hyperthyroidism or hypothyroidism and some cases of congenital hypothyroidism (CH) with the thyroid gland in situ. Primary CH is diagnosed by neonatal screening, which has been implemented for 40 years in developed countries and should be introduced worldwide, as early treatment prevents irreversible neurodevelopmental delay. Central CH is a rarer entity occurring mostly in association with multiple pituitary hormone deficiencies. Other rare disorders impair the action of thyroid hormones. Neonatal Graves' disease (GD) results from the passage of thyrotropin receptor antibodies (TRAbs) across the placenta, from mother to fetus. It may affect the fetuses and neonates of mothers with a history of current or past GD, but hyperthyroidism develops only in those with high levels of stimulatory TRAb activity. The presence of antibodies predominantly blocking thyroid-stimulating hormone receptors may result in transient hypothyroidism, possibly followed by neonatal hyperthyroidism, depending on the balance between the antibodies present. Antithyroid drugs taken by the mother cross the placenta, treating potential fetal hyperthyroidism, but they may also cause transient fetal and neonatal hypothyroidism. Early diagnosis and treatment are key to optimizing the child's prognosis. This review focuses on the diagnosis and management of these patients during the fetal and neonatal periods. It includes the description of a case of fetal and neonatal autoimmune hyperthyroidism.

Effect of initial levothyroxine dose on neurodevelopmental and growth outcomes in children with congenital hypothyroidism

OBJECTIVES

We designed a multicentre open prospective randomized trial to evaluate the risk-benefit profile of two different initial treatment schemes with levothyroxine (L-T4), 10-12.5 μg/kg/day vs 12.6-15 μg/kg/day, on growth and neurodevelopmental outcomes in children with congenital hypothyroidism (CH) detected by neonatal screening to identify the best range dose to achieve optimal neurocognitive development.

DESIGN PATIENTS AND METHODS

Children detected by neonatal screening were randomly assigned to receive an initial L-T4 dose of 10-12.5 μg/kg/day (Low) or 12.6-15 μg/kg/day (High). All patients underwent periodical clinical examination with measurement of growth parameters and measurement of TSH and FT4. Neurocognitive development was evaluated at the age of 24 months using Griffiths Mental Development Scales (GMDS) and cognitive and behavioral assessment was performed at 48 months of age using Wechsler Preschool and Primary scale of Intelligence (WIPPSI-III). The study was registered with clinicaltrials.gov (NCT05371262).

RESULTS

Treatment schemes below or above 12.5 μg/kg/day were both associated with rapid normalization of TSH and thyroid hormone levels in most patients with no differences in the risk of over- and under-treatment episodes in the first months of life. Growth parameters were normal and comparable between the two groups. Developmental quotients at 24 months of age were normal in both groups (Low 100.6 ± 15.5 vs High 96.9 ± 16.6). Likewise, at 4 years of age IQ and subtest scores were comparable between patients from Low and High (Total IQ 104.2 ± 11.4 vs 101.0 ± 20.3, Verbal IQ 103.9 ± 11.5 vs 98.7 ± 15.1, Performance IQ 105.3 ± 10.4 vs 100.3 ± 19.8). 6/45 CH patients (13.3%) showed a total IQ below 85 (73.7 ± 5.9) regardless of age at diagnosis, L-T4 starting dose, time of FT4 and TSH normalization and episodes of over and undertreatment. Worse socioeconomic status and delayed bone age at diagnosis were the only predictors of an increased risk of having suboptimal IQ at 24 and IQ at 48 months.

CONCLUSIONS

Our results indicate that initial treatment with L-T4, 10-12.5 μg/kg/day vs 12.6-15 μg/kg/day, are both associated with normal growth and neurodevelopmental outcomes in children with CH detected by neonatal screening. Further studies with a long-term follow-up on a larger number of patients are needed to confirm these results.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT05371262?term=NCT05371262&draw=2&rank=1 identifer NCT05371262.

An Overview on Different L-Thyroxine (l-T4) Formulations and Factors Potentially Influencing the Treatment of Congenital Hypothyroidism During the First 3 Years of Life

Congenital hypothyroidism (CH) is a relatively frequent congenital endocrine disorder, caused by defective production of thyroid hormones (THs) at birth. Because THs are essential for the development of normal neuronal networks, CH is also a common preventable cause of irreversible intellectual disability (ID) in children. Prolonged hypothyroidism, particularly during the THs-dependent processes of brain development in the first years of life, due to delays in diagnosis, inadequate timing and dosing of levothyroxine (l-thyroxine or l-T₄), the non-compliance of families, incorrect follow-up and the interference of foods, drugs and medications affecting the absorption of l-T₄, may be responsible for more severe ID. In this review we evaluate the main factors influencing levels of THs and the absorption of l-T₄ in order to provide a practical guide, based on the existing literature, to allow optimal follow-up for these patients.

The joint effect of congenital hypothyroidism and hypercaloric diet consumption as triggers of type 2 diabetes mellitus

Introduction

Congenital hypothyroidism affects metabolic and thyroid programming, having a deleterious effect on bodyweight regulation promoting metabolic diseases. This work aimed to demonstrate the development of type 2 diabetes mellitus (T2D) in animals with congenital hypothyroidism, only by the consumption of a mild hypercaloric diet in the extrauterine stage.

Methods

Two groups of female Wistar rats (n = 9): euthyroid and hypothyroid were used. Hypothyroidism was induced by a thyroidectomy with parathyroid reimplantation. Male offsprings post-weaning were divided into four groups (n = 10): euthyroid, hypothyroid, euthyroid + hypercaloric diet, and hypothyroid + hypercaloric diet. The hypercaloric diet consisted of ground commercial feed plus 20% lard and was administered until postnatal week 40. Bodyweight and energy intake were monitored weekly. Also, metabolic and hormonal markers related to cardiovascular risk, insulin resistance, and glucose tolerance were analyzed at week 40. Then, animals were sacrificed to perform the morphometric analysis of the pancreas and adipose tissue.

Results

T2D was developed in animals fed a hypercaloric diet denoted by the presence of central obesity, hyperphagia, hyperglycemia, dyslipidemia, glucose tolerance, insulin resistance and hypertension, as well as changes in the cytoarchitecture of the pancreas and adipose tissue related to T2D. The results show that congenital hypothyroid animals had an increase in metabolic markers and an elevated cardiovascular risk.

Conclusions

Congenital hypothyroid animals develop T2D, having the highest metabolic disturbances and a worsened clinical prognosis than euthyroid animals.

Health-Related Quality of Life in Patients With Early-Detected Central Congenital Hypothyroidism

CONTEXT

Central congenital hypothyroidism (CH) requires lifelong medical treatment. The majority of children with central CH have multiple pituitary hormone deficiencies (MPHD), but in some cases central CH is isolated. Most pituitary hormone deficiencies are associated with impaired health-related quality of life (HRQoL). However, studies on HRQoL in central CH are lacking.

OBJECTIVE

To evaluate HRQoL and fatigue in children and young adults with central CH, as well as parent perspectives.

DESIGN

Nationwide cross-sectional study comparing HRQoL between early-detected central CH patients and unaffected siblings with the Pediatric Quality of Life inventory (PedsQL™) and PedsQL Multidimensional Fatigue Scale. Participants ≥ 8 years old filled in self-reports; parents of participants aged 3 to 18 years filled in parent reports. Isolated central CH patients, MPHD patients, and siblings were compared using a linear mixed model and Tukey's post hoc test.

RESULTS

Eighty-eight patients and 52 siblings participated, yielding 98 self-reports and 115 parent reports. Isolated central CH patients (n = 35) and siblings showed similar scores on all subscales, both in the self-reports and parent reports. For MPHD patients (n = 53), self-reported scores were similar to those of siblings. Parent reported total HRQoL and fatigue scores were significantly poorer in MPHD patients compared with siblings (mean differences -10.2 and -9.4 points; P < 0.01), as were scores for physical functioning, social functioning and general fatigue.

CONCLUSION

Self-reported HRQoL scores in isolated central CH and MPHD patients were similar to siblings. However, parents reported significantly lower HRQoL and fatigue scores for MPHD patients, suggesting a difference in perceived limitations between MPHD patients and their parents.

Early-life disease environment and adult height in historical populations

Nutrition and the incidence of diseases during early life are considered environmental factors that determine people's height when they become adults. While there is extensive literature focusing on the relationship between physical growth, general mortality and infant mortality rates, few studies analyse the impact of certain disease groups on the final height of historical populations. Using regional mortality rates by causes of death, the main objective of this study is to determine the onset of the disease environment during early life for populations born in Spain between 1916 and 1930, and its relationship with the stature reached at 21 years of age. A population-averaged model is performed on epidemic-infectious, gastrointestinal, and congenital diseases during the gestation period and first year of life. The disease burden in early life had a statistically significant negative effect on adult stature. These results support the premise that an improvement in the disease environment could lead to a greater number of short children surviving and therefore a decrease in the average height.

Geographic variations in the incidence of congenital hypothyroidism in China: a retrospective study based on 92 million newborns screened in 2013-2018

Background:

Although congenital hypothyroidism (CH) has been widely studied in Western countries, CH incidence at different administrative levels in China during the past decade remains unknown. This study aimed to update the incidence and revealed the spatial pattern of CH incidence in the mainland of China, which could be helpful in the planning and implementation of preventative measures.

Methods:

The data used in our study were derived from 245 newborns screening centers that cover 30 provinces of the Chinese Newborn Screening Information System. Spatial auto-correlation was analyzed by Global Moran I and Getis-Ord Gi statistics at the provincial level. Kriging interpolation methods were applied to estimate a further detailed spatial distribution of CH incidence at city level throughout the mainland of China, and Kulldorff space scanning statistical methods were used to identify the spatial clusters of CH cases at the city level.

Results:

A total of 91,921,334 neonates were screened from 2013 to 2018 and 42,861 cases of primary CH were identified, yielding an incidence of 4.66 per 10,000 newborns screened (95% confidence interval [CI]: 4.62–4.71). Neonates in central (risk ratio [RR] = 0.84, 95% CI: 0.82–0.85) and western districts (RR = 0.71, 95% CI: 0.69–0.73) had lower probability of CH cases compared with the eastern region. The CH incidence indicated a moderate positive global spatial autocorrelation (Global Moran I value = 0.394, P < 0.05), and the CH cases were significantly clustered in spatial distribution. A most likely city-cluster (log-likelihood ratio [LLR] = 588.82, RR = 2.36, P < 0.01) and 25 secondary city-clusters of high incidence were scanned. The incidence of each province and each city in the mainland of China was estimated by kriging interpolation, revealing the most affected province and city to be Zhejiang Province and Hangzhou city, respectively.

Conclusion:

This study offers an insight into the space clustering of CH incidence at provincial and city scales. Future work on environmental factors need to focus on the effects of CH occurrence.

First Experiences with Newborn Screening for Congenital Hypothyroidism in Ulaanbaatar, Mongolia

Congenital hypothyroidism (CH) is among the most common conditions leading to intellectual disability, which can be prevented by early detection through newborn screening (NBS). In Mongolia, a regional screening program for CH was launched in 2000, which was supported by the International Atomic Energy Agency (IAEA) for the Asia Pacific Region. In our present study, a total of 23,002 newborns from nine districts in Ulaanbaatar were screened between 2012 and 2020, by the measurement of the thyroid-stimulating hormone (TSH) from dried blood spots, sampled 24 to 72 h after birth. The level of TSH was measured by the DELFIA assay. The overall CH prevalence confirmed at birth was 1/2091. The female-to-male ratio for CH cases was 1.8:1. The majority of patients were asymptomatic (72.7% of CH cases); umbilical hernia and cold or mottled skin were reported symptoms in patients with CH (27.3%). Thyroid dysgenesis (hypoplasia and agenesis) was the most common etiology, with a total of nine cases (81.8%) out of the eleven patients. The lapse between the birth date and the initiation of L-thyroxine treatment in CH-positive children was lower than 15 days in 63.64% of cases or 15 to 30 days in 36.36% of children. Further research is required to expand the screening coverage for CH in Mongolia.

[Neonatal screening for congenital hypothyroidism]

Congenital hypothyroidism (CH) is the leading cause of preventable mental retardation. It is mainly due to thyroid dysgenesis or dyshormonogenesis with normally located gland, and detected at birth in developed countries by systematic neonatal screening. The early treatment of patients with CH has successfully improved the prognosis and management of this disease. An increase in the incidence of congenital hypothyroidism with a normally located gland has been reported worldwide over the last three decades. The etiology of CH with a normally located gland remains elusive and about half of them demonstrate spontaneous resolution of CH within a few months (transient CH). They highlight the need to reevaluate thyroid function during follow-up.

Association of elevated neonatal thyroid-stimulating hormone levels with school performance and stimulant prescription for attention deficit hyperactivity disorder in childhood

Untreated severe newborn thyroid deficiency causes neurocognitive impairment; however, the impact of mild thyroid deficiency is not known. This study aimed to examine whether mildly elevated neonatal thyroid-stimulating hormone (TSH) levels are associated with poor school performance or stimulant prescription for attention deficit hyperactivity disorder (ADHD). This record-linkage study included 232,790 term-born infants in Australia with a TSH level below newborn screening threshold (< 15 mIU/L). Among our cohort, as TSH levels increased, the proportion of infants born low birthweight via caesarean section and with disadvantaged socioeconomic status increased. Multivariable logistic regression analysis showed that, compared with infants with 'normal' neonatal TSH level (< 5 mIU/L), those with neonatal TSH 10-15 mIU/L had an increased risk of being exempt from school testing (aOR 1.63 (95% CI 1.06-2.69)) or prescribed a stimulant for ADHD (aOR 1.57 (95% CI 1.10-2.24)), adjusted for perinatal and sociodemographic factors. Among a nested analysis of 460 sibling pairs, siblings with 'mildly elevated' TSH levels were more likely to be exempt from school tests compared with siblings with normal TSH levels (aOR 2.53, 95% CI 1.01-6.33).Conclusion: In this population cohort and sibling analysis, mildly elevated neonatal TSH levels were associated with being exempt from school testing due to significant or complex disability. What is Known: • Newborn screening for severe thyroid hormone deficiency has virtually eliminated congenital hypothyroidism-associated intellectual disability in developed countries. • The impact of mild thyroid hormone deficiency in infants is unclear. What is New: • Children with a mildly elevated neonatal TSH level below current newborn screening cut-offs have an increased likelihood of being exempt from school testing due to significant or complex disability compared with siblings and peers. This study includes a population-based and nested sibling analysis.

Role of thyroid hormones in normal and abnormal central nervous system myelination in humans and rodents

Thyroid hormones (THs) are instrumental in promoting the molecular mechanisms which underlie the complex nature of neural development and function within the central nervous system (CNS) in vertebrates. The key neurodevelopmental process of myelination is conserved between humans and rodents, of which both experience peak fetal TH concentrations concomitant with onset of myelination. The importance of supplying adequate levels of THs to the myelin producing cells, the oligodendrocytes, for promoting their maturation is crucial for proper neural function. In this review we examine the key TH distributor and transport proteins, including transthyretin (TTR) and monocarboxylate transporter 8 (MCT8), essential for supporting proper oligodendrocyte and myelin health; and discuss disorders with impaired TH signalling in relation to abnormal CNS myelination in humans and rodents. Furthermore, we explore the importance of using novel TH analogues in the treatment of myelination disorders associated with abnormal TH signalling.

Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology

Background: An ENDO-European Reference Network (ERN) initiative was launched that was endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology with 22 participants from the ENDO-ERN and the two societies. The aim was to update the practice guidelines for the diagnosis and management of congenital hypothyroidism (CH). A systematic literature search was conducted to identify key articles on neonatal screening, diagnosis, and management of primary and central CH. The evidence-based guidelines were graded with the Grading of Recommendations, Assessment, Development and Evaluation system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion. Summary: The recommendations include the various neonatal screening approaches for CH as well as the etiology (also genetics), diagnostics, treatment, and prognosis of both primary and central CH. When CH is diagnosed, the expert panel recommends the immediate start of correctly dosed levothyroxine treatment and frequent follow-up including laboratory testing to keep thyroid hormone levels in their target ranges, timely assessment of the need to continue treatment, attention for neurodevelopment and neurosensory functions, and, if necessary, consulting other health professionals, and education of the child and family about CH. Harmonization of diagnostics, treatment, and follow-up will optimize patient outcomes. Lastly, all individuals with CH are entitled to a well-planned transition of care from pediatrics to adult medicine. Conclusions: This consensus guidelines update should be used to further optimize detection, diagnosis, treatment, and follow-up of children with all forms of CH in the light of the most recent evidence. It should be helpful in convincing health authorities of the benefits of neonatal screening for CH. Further epidemiological and experimental studies are needed to understand the increased incidence of this condition.

Challenges in screening for congenital hypothyroidism: Optimization of thyrotropin cut-off values

BACKGROUND-AIM

Different protocols exist for newborn screening of congenital hypothyroidism (CH) worldwide, with different thyrotropin cut-off values for repetition and confirmation tests. This study aimed to assess local protocol in terms of specificity and improve our screening process by optimizing thyrotropin cut-off values. Subsequently, the cut-off values obtained were retrospectively applied to evaluate the number of tests avoided.

METHODS

Retrospective observational study between 2013 and 2019. All newborn children with a confirmation test for CH were considered for the study. ROC curve analysis was performed for thyrotropin cut-off value optimization in DBS which triggers a confirmatory test, and odds ratios were calculated. For individuals affected by the cut-off value modification, serum thyrotropin and free thyroxine in the confirmation test were analyzed for consideration of clinical outcomes.

RESULTS

A total of 72,133 newborn children were screened for CH, and 208 individuals were included in the study. Incidence in our population was 1:2,000 live births. The area under the ROC curve was 0.819 (CI 95%: 0.748-0.897). While the current cut-off value (thyrotropin ≥ 10mIU/L) had a specificity of 31.8% [ORs: 3.5 (CI 95%: 1.4-8.8)], the optimal cut-off value (thyrotropin ≥ 15mIU/L) yielded a specificity of 92.4% for the detection of CH and transient hypothyroidism [ORs: 15.9 (CI 95%: 7.1-35.8)], with no loss of sensitivity.

DISCUSSION

While keeping a maximum sensitivity, optimization of cut-off values may be of great use not only in management, but also in reducing family stress, which is of special relevance for the newborn.

Congenital Hypothyroidism

Congenital hypothyroidism (CH) is the commonest preventable cause of mental retardation in human species. It is so important for clinician to know its etiology epidemiology, clinical manifestation and treatment strategies. Since it is one of the rare serious diseases that should not be diagnosed clinically because late clinical features corresponds to advanced mental retardation, the neonatal screening detection is the best and preferable way of early diagnosis of this congenital disease. Confirmatory laboratory and radiological diagnostic tests should be performed immediately after the positive neonatal screening test. In order to prevent mental defects and to maintain long term clinical as well as biochemical euthyroidism in affected children its diagnosis approach, medical treatment and follow-up should be well established knowledge to all pediatricians during the childhood period and later on to general practitioners when these individuals grow up as adults. Congenital hypothyroidism is a potentially serious disease that we need to emphasize on early detection, using proper diagnostic tools and early and planned therapeutic approach.

Congenital hypothyroidism as a risk factor for hearing and parents' knowledge about its impact on hearing

Aim

To evaluate the hearing of children with congenital hypothyroidism (CH) and to analyze the knowledge that parents’ have on the possible auditory impacts of the disease.

Methods

A total of 263 parents/guardians were interviewed about aspects of CH and hearing. Audiological evaluation was performed on 80 participants, divided into two groups: with CH (n= 50) and without CH (n=30). Clinical and laboratory CH data were obtained from medical records, pure tone auditory thresholds and acoustic reflexes were analyzed. The auditory data was compared between groups. Student’s t-test and Chi-square were used for statistical analysis at a significance level of 5% (p ≤0.05).

Results

The majority (78%), of the parents were unaware that CH when not treated early is a potential risk to hearing. There was no correlation between socioeconomic class and level of information about CH and hearing (p>0,05; p=0.026). There was a statistically significant difference between the auditory tone thresholds of the groups and between the levels of intensity necessary for the triggering of the acoustic reflex. The group with CH presented the worst results (p≤0.05) and absence of acoustic reflex in a normal tympanometric condition.

Conclusions

Children with CH are more likely to develop damage to the auditory system involving retrocochlear structures when compared to healthy children, and that the disease may have been a risk factor for functional deficits without deteriorating hearing sensitivity. The possible impacts of CH on hearing, when not treated early, should be more publicized among the parents/guardians of this population.

Transient Hypothyroidism During Lactation Alters the Development of the Corpus Callosum in Rats. An in vivo Magnetic Resonance Image and Electron Microscopy Study

Magnetic resonance imaging (MRI) data of children with late diagnosed congenital hypothyroidism and cognitive alterations such as abnormal verbal memory processing suggest altered telencephalic commissural connections. The corpus callosum (CC) is the major inter-hemispheric commissure that contra-laterally connects neocortical areas. However, in late diagnosed neonates with congenital hypothyroidism, the possible effect of early transient and chronic postnatal hypothyroidism still remains unknown. We have studied the development of the anterior, middle and posterior CC, using in vivo MRI and electron microscopy in hypothyroid and control male rats. Four groups of methimazole (MMI) treated rats were studied. One group, as a model for early transient hypothyroidism, was MMI-treated from postnatal day (P) 0 to P21; some of these rats were also treated with L-thyroxine (T4) from P15 to 21. Another group modeling chronic hypothyroid, were treated with MMI from P0 to 150 and from embryonic day 10 to P170. The results obtained from these groups were compared with same age control rats. The normalized T2 signal obtained using MRI was higher in MMI-treated rats and correlated with a low number and percentage of myelinated axons. The number and density of myelinated axons decreased in transient and chronic hypothyroid rats at P150. The g-ratio (inner to outer diameter ratio) and the estimated conduction velocity of myelinated axons were similar between MMI-treated and controls, but the conduction delay decreased in the posterior CC of MMI-treated rats compared to controls. These data show that early postnatal transient and chronic hypothyroidism alters CC maturation in a way that may affect the callosal transfer of information. These alterations cannot be reversed after delayed T4-treatment. Our data support the findings of neurocognitive delay in late T4-treated children with congenital hypothyroidism.

A Success Story: Review of the Implementation and Achievements of the National Newborn Screening Program for Congenital Hypothyroidism in Iran

CONTEXT

Today, newborn screening for congenital hypothyroidism (CH) as one of the significant achievements in preventive medicine is integrated into the health systems of many countries worldwide. The national newborn screening for early identification of CH disorder in Iran was established in 2004. The purpose of this study was to review the national newborn screening for CH and its achievements in Iran.

EVIDENCE ACQUISITION

In this study, we reviewed the structures, processes, main indicators, and achievements during the 15 years of implementing the national neonatal screening program for the diagnosis and treatment of CH in Iran.

RESULTS

Primary TSH measurement with backup thyroxine (T4) determination in infants with high TSH levels was used as the screening strategy in Iran. The coverage of this screening program was higher than 98%. By the end of 2017, 1,501,624 neonates were screened, among which 40,773 were diagnosed with CH and treated based on the national guidelines. The average incidence rate of CH during these years was approximately 2.6:1,000 live births.

CONCLUSIONS

The performance of the newborn screening program for congenital hypothyroidism in Iran is favorable, with over a 95% coverage rate. Due to the high recall rate and incidence rate of CH, it is essential to monitor the screening program in the country and also to conduct further studies to determine the main risk factors for the high recall rate and incidence of this congenital error.

Update on congenital hypothyroidism

PURPOSE OF REVIEW

The present review summarizes recent advances in the diagnosis and management of patients with congenital hypothyroidism.

RECENT FINDINGS

Although most newborn screening strategies are designed to detect severe primary hypothyroidism that presents shortly after birth, some infants display a pattern of delayed TSH rise despite normal initial newborn screening. Recent studies suggest that delayed TSH rise may be more common and more severe than previously recognized. Although much less common than primary hypothyroidism, central congenital hypothyroidism is as likely to be of moderate or severe degree, which has implications for its detection and treatment. The discovery of new genetic causes of central congenital hypothyroidism, including the X-linked genes IGSF1, TBL1X, and IRS4, has begun to expand our understanding of thyroid axis regulation. Recent long-term data indicate that current treatment recommendations for congenital hypothyroidism result in grossly normal neurocognitive outcomes even in severely affected patients, and that overtreatment may not be as harmful as previously suspected. Liquid levothyroxine is now commercially available in the United States, but more studies are needed to determine optimal dosing using this formulation.

SUMMARY

Prompt identification and adequate treatment of patients with congenital hypothyroidism is critical to optimize outcomes. New information continues to accumulate about how to improve detection of congenital hypothyroidism in specific subgroups of infants (particularly those with delayed TSH rise and central hypothyroidism) and about treatment of patients with this disorder.

Effect of delayed diagnosis and treatment of congenital hypothyroidism on intelligence and quality of life: an observational study

BACKGROUND Congenital hypothyroidism is one of the most prevalent, albeit preventable causes of intellectual disability. This study determined the intellectual outcome and health-related quality of life (QoL) in children and adolescents clinically diagnosed with congenital hypothyroidism and the associations among age of starting thyroid hormone treatment, current free thyroxine (FT4) level, intelligence quotient (IQ), and QoL.METHODS Intelligence (Wechsler scales) and QoL (PedsQLTM 4.0 parent proxy-report) tests were administered to 25 patients with congenital hypothyroidism in the pediatric clinic of Cipto Mangunkusumo Hospital, Jakarta. Nineteen patients underwent thyroid ultrasonography or scintigraphy to determine the etiology of congenital hypothyroidism.RESULTS A total of 25 patients with the median age of 9 (5.5–12.5) years were recruited. Eighteen patients had a total IQ of <70. The age of treatment initiation did not correlate with full scale IQ (FSIQ) (r = −0.261, p = 0.071) and verbal IQ (VIQ) (r = −0.232, p = 0.265). The late initiation of treatment was correlated with lower performance IQ (PIQ) (r = −0.325, p = 0.025). The higher current FT4 levels was correlated with higher scores ofFSIQ (r = 0.314, p = 0.046) and PIQ (r = 0.320, p = 0.043). The late initiation of treatment (r = 0.006, p = 0.980) and higher current FT4 levels (r = 0.246, p = 0.310) were not correlated with QoL. Hemiagenesis of thyroid gland was the most common etiology.CONCLUSIONS The late initiation of thyroid hormone substitution in patients with congenital hypothyroidism negatively affects intellectual abilities.

The Effects of Amiodarone on Thyroid Function in Pediatric and Young Adult Patients

CONTEXT

Amiodarone is used in patients with arrhythmias, but thyroid dysfunction [amiodarone-induced thyrotoxicosis (AIT) or amiodarone-induced hypothyroidism (AIH)] is a common adverse effect. As the onset of AIT and AIH has not been studied in children, the timing of dysfunction and long-term monitoring are not known in this population.

OBJECTIVE

To describe the incidence and timing of amiodarone-induced thyroid dysfunction in children and adolescents, with a secondary aim to identify risk factors for amiodarone-induced thyroid dysfunction, and to identify variance in thyroid hormone surveillance and treatment.

DESIGN

Retrospective review of thyroid dysfunction in children and young adults treated with amiodarone between 2007 and 2018.

SETTING

Children's Hospital of Philadelphia.

PATIENTS

Children and young adults treated with amiodarone.

MAIN OUTCOME MEASURES

Prevalence of amiodarone-induced thyroid dysfunction.

RESULTS

Of 484 patients, 190 had thyroid-function testing; 17.3% were found to have subclinical hypothyroidism, and 13.7% testing developed hypothyroidism. Hyperthyroidism occurred in 2.1%. In patients with subclinical hypothyroidism, 63% returned to normal thyroid function without thyroid hormone replacement. Only 26% of patients with hypothyroidism had spontaneous normalization of thyroid function. Twenty-five percent of AIT patients had spontaneous normalization of thyroid function.

CONCLUSIONS

This study looks at a pediatric and young-adult population in an effort to describe the natural history of amiodarone-induced thyroid dysfunction. Based on our data, we recommend that a complete thyroid-function panel be obtained within the first week and then at weekly intervals for the first 5 weeks after initiation. The majority of thyroid dysfunction was noted within the first 35 days of treatment.

Thyroid hormone therapy in congenital hypothyroidism and pediatric hypothyroidism

The evaluation and management of hypothyroidism in children are similar to adults, but there are important differences based on the dependence on normal thyroid function for neurocognitive and physical development. In the pediatric population, hypothyroidism is frequently categorized as congenital or acquired hypothyroidism, depending on the age of presentation and the underlying etiology. The evaluation and management of children and adolescents with hypothyroidism are determined by the etiology as well as by the age at diagnosis, severity of the hypothyroidism, and the response to thyroid hormone replacement therapy. Children and adolescents require higher weight-based doses for thyroid hormone replacement than do adults, likely due to a shorter half-life of thyroxine (T4) and triiodothyronine (T3) in children, but weight-based dose requirements decrease as the child advances into adulthood. Multiple gaps in knowledge remains regarding how to optimize the treatment of hypothyroidism in pediatric patients, including (but not limited to) the selection of patients with subclinical hypothyroidism for treatment, and the potential benefit of combined LT3/LT4 therapy for patients with persistent symptoms and/or low T3 on LT4 monotherapy. The life-long impact on growth and development, and potentially on long-term cardiovascular and psychosocial health, are significant and highlight the importance of future prospective studies in pediatric patients to explore these areas of uncertainty.

Maternal education and newborn thyroid-stimulating hormone level in a congenital hypothyroidism screening program

Objective: To examine the relationship between neonatal thyroid function and the formal education of mothers.Study design: Participants came from a population-based congenital hypothyroidism (CH) screening program in Tianjin, China.Methods: Of 66,390 registered births in 2015, 60,568 mothers and newborns had complete data. Mothers were categorized into one of four categories based on their educational attainment: (a) midschool or less; (b) high school or equivalent; (c) university; or (d) post graduate. Newborn thyroid-stimulating hormone (TSH) level was measured on day 3-7. Two neonatal groups were created using cutoffs of TSH > 10 μIU/ml and TSH > 20 μIU/ml. Odds ratios (OR) for CH risk by maternal education were estimated from logistic regression models after adjusting for potential confounders.Results: For TSH > 10 μIU/ml, the screen positive incidence rate for CH was 1:201 or 4.98 per 1000 births; for TSH > 20 μIU/ml, the incidence rate was 1:2222 or 0.45 per 1000 births. Screen positive incidence rates decreased with increasing maternal education level. Compared to mothers with a postgraduate education, the ORs (95% CI) for midschool or less, high school or equivalent, and university were 2.09 (1.08, 4.04), 1.45 (0.73, 2.90), and 1.61 (0.85, 3.06) using a cutoff of TSH > 10 μIU/ml. At the higher cutoff of TSH > 20 μIU/ml ORs (95% CI) for midschool or less and high school or equivalent were 3.05 (1.20,7.74) and 3.34 (1.24, 8.97), when compared to a composite reference category of university and postgraduate level education.Conclusion: Maternal education is inversely related to neonatal thyroid function though the mechanism remains unexplained.

Transient Hypothyroidism During Lactation Arrests Myelination in the Anterior Commissure of Rats. A Magnetic Resonance Image and Electron Microscope Study

Thyroid hormone deficiency at early postnatal ages affects the cytoarchitecture and function of neocortical and telencephalic limbic areas, leading to impaired associative memory and in a wide spectrum of neurological and mental diseases. Neocortical areas project interhemispheric axons mostly through the corpus callosum and to a lesser extent through the anterior commissure (AC), while limbic areas mostly project through the AC and hippocampal commissures. Functional magnetic resonance data from children with late diagnosed congenital hypothyroidism and abnormal verbal memory processing, suggest altered ipsilateral and contralateral telencephalic connections. Gestational hypothyroidism affects AC development but the possible effect of transient and chronic postnatal hypothyroidism, as occurs in late diagnosed neonates with congenital hypothyroidism and in children growing up in iodine deficient areas, still remains unknown. We studied AC development using in vivo magnetic resonance imaging and electron microscopy in hypothyroid and control male rats. Four groups of methimazole (MMI) treated rats were studied. One group was MMI-treated from postnatal day (P) 0 to P21; some of these rats were also treated with L-thyroxine (T4) from P15 to P21, as a model for early transient hypothyroidism. Other rats were MMI-treated from P0 to P150 and from embryonic day (E) 10 to P170, as a chronic hypothyroidism group. The results were compared with age paired control rats. The normalized T2 signal using magnetic resonance image was higher in MMI-treated rats and correlated with the number and percentage of myelinated axons. Using electron microscopy, we observed decreased myelinated axon number and density in transient and chronic hypothyroid rats at P150, unmyelinated axon number increased slightly in chronic hypothyroid rats. In MMI-treated rats, the myelinated axon g-ratio and conduction velocity was similar to control rats, but with a decrease in conduction delays. These data show that early postnatal transient and chronic hypothyroidism alters AC maturation that may affect the transfer of information through the AC. The alterations cannot be recovered after delayed T4-treatment. Our data support the neurocognitive delay found in late T4-treated children with congenital hypothyroidism.

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 <10 µg/kg.

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.

Central congenital hypothyroidism caused by maternal thyrotoxicosis

Central congenital hypothyroidism (CCH) is a rare and underdiagnosed disease that sometimes is caused by maternal Graves' disease. We report a case of CCH caused by undiagnosed, initially antibody-negative maternal thyrotoxicosis with possible disruption of fetal hypothalamic-pituitary-thyroid axis maturation. In CCH, maternal thyroid disease should be considered.

Congenital Hypothyroidism

Congenital hypothyroidism is common and can cause severe neurodevelopmental morbidity. Prompt diagnosis and treatment are critical to optimizing long-term outcomes. Universal newborn screening is an important tool for detecting congenital hypothyroidism, but awareness of its limitations, repeated screening in high-risk infants, and a high index of clinical suspicion are needed to ensure that all affected infants are appropriately identified and treated. Careful evaluation will usually reveal the etiology of congenital hypothyroidism, which may inform treatment and prognosis. Early and adequate treatment with levothyroxine results in excellent neurodevelopmental outcomes for most patients with congenital hypothyroidism.

Newborn Screening in the US May Miss Mild Persistent Hypothyroidism

OBJECTIVE

To determine if newborn screening (NBS) programs for congenital hypothyroidism in the US use thyroid-stimulating hormone (TSH) cutoffs that are age adjusted to account for the physiologic 4-fold reduction in TSH concentrations over the first few days of life.

STUDY DESIGN

All NBS programs in the US were contacted and asked to provide information on their NBS protocols, TSH cutoffs, and whether these cutoffs were age adjusted.

RESULTS

Of 51 NBS programs, 28 request a repeat specimen if the initial eluted serum TSH concentration is mildly increased (between the cutoff and a median upper limit of 50 mU/L), whereas 14 programs perform a routine second screen in all infants. Although these specimens are typically collected between 1 week and 1 month of life, 16 of the 28 programs with a discretionary second test and 8 of 14 programs with a routine second test do not have age-adjusted TSH cutoffs after the first 48 hours of life.

CONCLUSIONS

There is variation in NBS practices for screening for congenital hypothyroidism across the US, and many programs do not adjust the TSH cutoff beyond the first 2 days of life. Samples are processed when received from older infants, often to retest borderline initial results. This approach will miss congenital hypothyroidism in infants with persistent mild TSH elevations. We recommend that all NBS programs provide age-adjusted TSH cutoffs, and suggest developing a standard approach to screening for congenital hypothyroidism in the US.

Pediatric Hypothyroidism: Diagnosis and Treatment

Thyroid hormone has important physiologic functions in nearly every organ system. The critical role of thyroid hormone in growth and in physical and neurologic development lends particular importance to the prompt diagnosis and appropriate treatment of hypothyroidism in infants and children. Congenital hypothyroidism is common and has potentially devastating neurologic consequences. While the approach to diagnosis and treatment of severe congenital hypothyroidism is well established, data continue to emerge about the genetic causes, clinical significance, and prognosis of the milder forms of congenital hypothyroidism that are increasingly being diagnosed by newborn screening. Similarly, the diagnosis and treatment of severe acquired hypothyroidism is straightforward and clearly of clinical benefit, but uncertainty remains about the optimal management of mild subclinical hypothyroidism. This review summarizes current knowledge of the causes, clinical manifestations, diagnosis, treatment, and prognosis of hypothyroidism in infants and children, with a focus on recent developments and areas of uncertainty in this field.

Congenital Hypothyroidism: Role of Nuclear Medicine

Thyroid scintigraphy holds a key place in the etiologic workup of neonatal hypothyroidism. Routine screening for this disorder in maternity hospitals in industrialized countries, for nearly 40 years, has permitted early treatment and thereby helped to prevent its physical and mental complications. Neonatal hypothyroidism affects approximately 1 in 3000 births. The most common causes are abnormal thyroid gland development and defective hormone synthesis by an eutopic thyroid gland. The incidence of the latter has risen in recent years, for reasons that remain unclear. A thorough etiologic workup helps to determine the disease type. Current guidelines recommend thyroid imaging by means of ultrasound and scintigraphy. Ultrasound should be done by a practitioner trained to examine the cervical region of newborns, as the thyroid is very small and must be distinguished from the particular aspect of the "thyroid empty lodge." Ultrasound lacks sensitivity for detecting small ectopic glands but is the gold standard for measuring thyroid dimensions. Scintigraphy provides an etiologic diagnosis in most cases. The two isotopes used in this setting are technetium-99m and iodine-123. The latter isotope gives more contrast and allows the perchlorate discharge test to be performed to detect abnormal iodide organification in the neonate with an eutopic thyroid. If scintigraphy cannot be performed during the neonatal period, a postponed procedure can be achieved after 3 years of age. Close cooperation between the nuclear medicine physician and the pediatric endocrinologist is crucial for timely and optimized scintigraphy.

Association between borderline neonatal thyroid-stimulating hormone concentrations and educational and developmental outcomes: a population-based record-linkage study

BACKGROUND

Congenital hypothyroidism causes intellectual delay unless identified and effectively treated soon after birth. Newborn screening has almost eliminated intellectual disability associated with congenital hypothyroidism. However, clinical uncertainty remains about infants with thyroid-stimulating hormone (TSH) concentrations less than the newborn screening cutoffs. We assessed the association between neonatal TSH concentrations and educational and developmental outcomes.

METHODS

We did a population-based record-linkage study of all liveborn infants undergoing newborn screening from 1994 to 2008 in New South Wales, Australia, with assessments of childhood development or school performance. Very-low-birthweight babies (<1500 g) were excluded. Developmental and educational outcomes were obtained and these were linked to individual records by the New South Wales Centre for Health Record Linkage. The primary educational outcome was the proportion of students with National Assessment Program Literacy and Numeracy (NAPLAN) results lower than the national minimum standard in reading or numeracy measured at all ages, and the primary developmental outcome was the proportion of children who were classified as being developmentally high risk (vulnerable in two or more of the five developmental domains assessed by the Australian Early Development Census) at age 4-6 years. The proportions of infants with each outcome were calculated per percentile (0-100) of TSH concentration. Multivariable logistic regression was used to account for potential confounding by maternal and fetal variables known to affect neonatal TSH concentrations or neurodevelopmental outcomes.

FINDINGS

503 706 infants had a neonatal TSH result that linked to a developmental or educational outcome. 149 569 infants born between 2002 and 2008 were linked to an Australian Early Development Census developmental outcome and 354 137 were linked to a NAPLAN educational outcome. Median follow-up for educational outcome was 10 years (IQR 8-12) and for developmental outcome was 5 years (5-6). 5·5% (14 137 of 257 752) of infants scored less than the national minimum standard for numeracy in percentiles lower than the 75th percentile and this increased with each increase of percentile group to 11·3% (15 of 133) of infants with a TSH concentration between the 99·90th and 99·95th percentile. Infants with a neonatal TSH concentration in the 99·95th percentile or higher (above newborn screening cutoff) and likely to have diagnosed and treated congenital hypothyroidism had similar results to infants with a TSH concentration lower than the 75th percentile for both educational and developmental outcomes. Infants with a neonatal TSH concentration between the 99·5th and 99·9th percentile were more likely to have special needs (adjusted odds ratio [aOR] 1·68, 95% CI 1·23-2·30), poor numeracy performance (aOR 1·57, 1·29-1·90), and developmentally high risk (aOR 1·52, 1·20-1·93).

INTERPRETATION

We found an association between neonatal TSH concentrations lower than the present newborn screening thresholds and poor educational and developmental outcomes. This association needs further investigation to assess whether assessment and treatment of these infants might improve their long-term cognitive outcomes.

FUNDING

Australian National Health and Medical Research.

Poorly Controlled Congenital Hypothyroidism due to an Underlying Allgrove Syndrome

BACKGROUND

Congenital hypothyroidism of thyroidal origin (CHT) is a common disorder in pediatric endocrinology practices, which can be difficult to manage. Elevated thyrotropin (TSH) concentrations are in the great majority of cases explained by poor compliance to levothyroxine therapy.

METHODS

Case description.

RESULTS

We present a boy with CHT, with 2 heterozygous mutations in the TSH receptor gene, who showed persistently elevated TSH concentrations and psychomotor retardation, initially misinterpreted as malcompliance. At the age of 4 years, he was diagnosed with adrenal insufficiency, wherefore a broad diagnostic search was initiated. After the start of glucocorticoid replacement therapy, his TSH normalized and the levothyroxine could be lowered. At the age of 6 years, his TSH increased again, this time caused by malabsorption of levothyroxine due to esophageal achalasia. In retrospect, alacrima was also present and the diagnosis of Allgrove syndrome was genetically confirmed. The CHT was considered a separate disease entity.

CONCLUSIONS

In case of persistently elevated TSH levels in children with CHT, causes other than noncompliance must be considered. Second, in establishing the cause of adrenal insufficiency, specific symptoms, such as alacrima, are easily overlooked. Third, Allgrove syndrome is a rare disorder, in which diagnostic delay can lead to potentially life-threatening complications.

Compound heterozygous mutations (p.T561M and c.2422delT) in the TPO gene associated with congenital hypothyroidism

BACKGROUND

The objective of the study was to determine the genetic basis of goitrous congenital hypothyroidism (GCH) in Chinese siblings.

METHODS

The proband and her younger brother with GCH were enrolled for molecular analysis of the dual oxidase 2 (DUOX2), dual oxidase maturation factor 2 (DUOXA2), and thyroid peroxidase (TPO) genes. Mutation screening was performed by Sanger sequencing the fragments amplified from genomic DNA. The detected mutations were verified among the close relatives of the patients and 105 controls. All participants underwent clinical examination and laboratory tests.

RESULTS

Analysis of the TPO gene revealed two heterozygous mutations, the frameshift mutation c.2422delT in the exon14 of the TPO gene, that has been reported previously, and a novel missense mutation c.1682C>T (p.T561M) in the exon10 of the TPO gene. Nine family members of the patients were enrolled for mutation screening. The patients' parents and grandfathers harbored a single heterozygous mutation. The germline mutations from this family were consistent with an autosomal recessive inheritance pattern. No mutations in the DUOXA2 and DUOX2 genes were observed.

CONCLUSIONS

The inactivating mutations (c.2422delT and p.T561M) in the TPO gene were identified in the Chinese siblings with GCH. The compound heterozygous mutations can cause GCH.

Effects of Maternal Iodine Nutrition and Thyroid Status on Cognitive Development in Offspring: A Pilot Study

BACKGROUND AND OBJECTIVE

Maternal iodine nutrition and thyroid status may influence neurocognitive development in offspring. This study investigated the effects on the intelligence quotient (IQ) of children born to mothers with different levels of iodine supplementation, with or without the administration of levothyroxine (LT4), prior to and during pregnancy.

PATIENTS AND METHODS

This pilot, prospective, observational study included four study groups, each comprising 15 mother-child pairs, identified on the basis of maternal histories of iodized salt consumption and LT4 treatment prior to and during pregnancy. The groups were labeled as follows: iodine (I), no iodine (no-I), iodine + LT4 (I + T4), and no iodine + LT4 (no-I + T4). IQ tests were administered to children at 6-12 years of age with the Wechsler Intelligence Scale for Children-3rd Edition (WISC-III), with full-scale IQ (FSIQ), verbal IQ (VIQ), and performance IQ (PIQ) being evaluated.

RESULTS

Children of I and I + T4 mothers had similar verbal, performance, and FSIQs, which were 14, 10, and 13 points higher, respectively, than children born to no-I and no-I + T4 mothers. A positive association was found between VIQ and maternal urinary iodine (β = 1.023 [confidence interval (CI) 1.003-1.043]; p = 0.028), but not with maternal free thyroxine concentrations at any stage of pregnancy. Overall, the prevalence of borderline or defective cognitive function was more than threefold higher in the children of mothers not using iodized salt than of those mothers using it (76.9% vs. 23.1%, odds ratio 7.667 [CI 2.365-24.856], χ2 = 12.65; p = 0.0001).

CONCLUSIONS

Neuro-intellectual outcomes in children appear to be more dependent on their mothers' nutritional iodine status than on maternal thyroid function. These results support the growing body of evidence that prenatal, mild-to-moderate iodine deficiency adversely affects cognitive development later in life, with a seemingly greater impact on verbal abilities.

Ophthalmic Manifestations in Children With Congenital Hypothyroidism

PURPOSE

To evaluate the frequencies of ophthalmic abnormalities in children with congenital hypothyroidism.

METHODS

A total of 121 patients with a history of congenital hypothyroidism, aged 1 to 216 months, were included in the study. The initial ophthalmological examinations and demographic data of patients who were examined between April 2013 and April 2015 were retrospectively reviewed. Accompanying systemic abnormalities were also noted.

RESULTS

Ophthalmic pathology was determined in 40.4% (49 of 121) of patients with congenital hypothyroidism, of which 79.5% (39 of 49) had significant refractive errors and 32.6% (16 of 49) had strabismus. Systemic abnormalities were observed in 74.3% (90 of 121) of the children, among which 47.1% (57 of 121) were congenital heart defects and 38.0% (46 of 121) were neurologic abnormalities. A high prevalence of Down syndrome (17.3%; 21 of 121) and atopic dermatitis (8.2%; 10 of 121) was detected among patients with congenital hypothyroidism.

CONCLUSIONS

In addition to many associated systemic abnormalities, ophthalmic pathologies may also occur in children with congenital hypothyroidism. Thus, routine ophthalmological examination is recommended for these children, starting from the time of initial diagnosis.

Final height in Italian patients with congenital hypothyroidism detected by neonatal screening: a 20-year observational study

BACKGROUND

Linear growth and final height are reported as normal in congenital hypothyroid patients in the neonatal screening era.

METHODS

We evaluated the final height in 215 patients with congenital hypothyroidism to assess if it improved over the last 2 decades.

RESULTS

Final height (-0.1 ± 1.0 SDS) was higher than target height (-0.8 ± 1.0 SDS, p < 0.001) and not different among the 4 quartiles for birthdate. It was correlated with target height (r(2) = 0.564, p < 0.001) and height at puberty onset (r(2) = 0.685, p < 0.001), but not with age at diagnosis or the starting LT4/kg/day dose. The curve fitting analysis showed that the age at diagnosis progressively decreased during the 20-year study period, while the target height and the starting LT4/kg/day increased. Final height was not affected by the birthdate, the age at diagnosis, the starting LT4 dose.

CONCLUSIONS

The final height is higher than the target height, but despite the improvement in the screening and the treatment, it did not improve over the last 20 years. These findings are in keeping with the described secular trend and suggest that earlier diagnosis and replacement therapy do not significantly modify final height in these patients.

Treatment of congenital thyroid dysfunction: Achievements and challenges

The active thyroid hormone tri-iodothyronine (T3) is essential for a normal development of children. Especially within the first years of life, thyroid hormone is pivotal in enabling maturation of complex brain function and somatic growth. The most compelling example for a life without thyroid hormone are those historical cases of children who came to birth without a thyroid gland - as shown in autopsy-studies- and who suffered from untreated hypothyroidism, at that time initially called "sporadic congenital hypothyroidism" (CH). In the last decades huge achievements resulted in a normal development of these children based on newborn screening programs that enable an early onset of a high dose LT4-treatment. Further progress will be necessary to further tailor an individualized thyroid hormone substitution approach and to identify those more complex patients with congenital hypothyroidism and associated defects, who will not benefit from an even optimized LT4 therapy. Besides the primary production of thyroid hormone a variety of further mechanisms are necessary to mediate the function of T3 on normal development that are located downstream of thyroid hormone production. Abnormalities of these mechanisms include the MCT8-transport defect, deiodinase-insufficiency and thyroid hormone receptor alpha-and beta defects. These thyroid hormone resistant diseases can not be treated with classical LT4 substitution alone. The development of new treatment options for those rare cases of thyroid hormone resistance is one of the most challenging tasks in the field of congenital thyroid diseases today.

Even in the era of congenital hypothyroidism screening mild and subclinical sensorineural hearing loss remains a relatively common complication of severe congenital hypothyroidism

Only few studies have focused on neurosensory hearing function of patients with congenital hypothyroidism (CH) identified by CH screening programs and treated early and, therefore, this issue remains still controversial. The aim of this study was to ascertain whether an early and adequate replacement treatment may be able to prevent sensorineural hearing loss in 32 screened children with CH and no associated risk factors for neuro-otologic alterations. These patients were recruited according to highly selective criteria aiming to preliminarily exclude the negative interference of both treatment variables and other underlying risk factors. All the selected patients underwent, at a median age of 15.4 years, an audiologic investigation, which evidenced a mild and subclinical hearing loss in 25% of them. The poorest hearing scores were recorded in the individuals with athyreosis and in those with absence of distal femur bony nucleus at CH diagnosis. The prevalence of hearing impairment was significantly higher in CH patients than in 32 age-matched control subjects with no CH (χ(2) = 6.3, p < 0.025). In light of these findings, we concluded that: a) 25% of CH patients detected by CH screening may show, at a median age of 15.4 years, a mild and subclinical hearing impairment, despite early and adequate replacement treatment; b) the risk of hearing loss is higher in CH young patients than in age-matched control subjects without CH; c) the risk of hearing loss is closely associated with the severity of CH; d) this risk is particularly relevant in the children with pre-natal onset of hypothyroidism.