A population-based study on the frequency of additional congenital malformations in infants with congenital hypothyroidism: data from the Italian Registry for Congenital Hypothyroidism (1991-1998)

Congenital hypothyroidism in children with eutopic gland or thyroid hemiagenesis: prognostic factors for transient vs. permanent hypothyroidism

OBJECTIVES

More than one third of children with congenital hypothyroidism (CH) and thyroid gland in situ (or eutopic gland) have transient hypothyroidism. It remains difficult to determine early on whether hypothyroidism will be transient which may cause overtreatment and its complications in these children. Our primary aim was to determine prognostic factors for transient hypothyroidism in children with congenital hypothyroidism and eutopic gland or thyroid hemiagenesis.

METHODS

We retrospectively reviewed medical records of 111 children, born between 1996 and 2017, diagnosed with congenital hypothyroidism and eutopic gland or hemiagenesis and treated at the Nancy Regional and University Hospital.

RESULTS

Fifty four infants (48.6%) had permanent congenital hypothyroidism (PCH) and 57 (51.4%) transient congenital hypothyroidism (TCH). Prognostic factors for TCH included prematurity, twin pregnancy, low birth weight and Apgar score <7, while low FT3 at diagnosis, maternal levothyroxine treatment, a family history of thyroid dysfunction and TSH ≥10 mUI/L while receiving treatment were associated with PCH. Knee epiphyses on X-ray at diagnosis were absent only in children with PCH. The median levothyroxine dose during follow-up was significantly lower in the TCH group compared to the PCH group. A levothyroxine dose of ≤3.95, ≤2.56, ≤2.19 and ≤2.12 μg/kg/day at 6 months, 1, 2 and 3 years of follow-up, respectively, had the best sensitivity-to-specificity ratio for predicting TCH.

CONCLUSIONS

Even though it remains difficult to predict the course of hypothyroidism at diagnosis, we were able to identify several prognostic factors for TCH including perinatal problems and lower levothyroxine requirements that can guide the physician on the evolution of hypothyroidism. Clinical Trial Registration Number: NCT04712760.

Guidelines for Newborn Screening of Congenital Hypothyroidism (2021 Revision)

Purpose of developing the guidelines: Newborn screening (NBS) for congenital hypothyroidism (CH) was started in 1979 in Japan, and early diagnosis and treatment improved the intelligence prognosis of CH patients. The incidence of CH was once about one in 5,000-8,000 births, but has been increased with diagnosis of subclinical CH. The disease requires continuous treatment and specialized medical facilities should conduct differential diagnosis and treatment in patients who are positive by NBS to avoid unnecessary treatment. The Guidelines for Mass Screening of Congenital Hypothyroidism (1998 version) were developed by the Mass Screening Committee of the Japanese Society for Pediatric Endocrinology in 1998. Subsequently, the guidelines were revised in 2014. Here, we have added minor revisions to the 2014 version to include the most recent findings. Target disease/conditions: Primary congenital hypothyroidism. Users of the Guidelines: Physician specialists in pediatric endocrinology, pediatric specialists, physicians referring pediatric practitioners, general physicians, laboratory technicians in charge of mass screening, and patients.

Congenital Anomalies in Infant With Congenital Hypothyroidism: A Review of Pathogenesis, Diagnostic Options, and Management Protocols

Thyroid hormones (TH) regulate growth, nervous system myelination, metabolism, and physiologic functions in nearly every organ system. Congenital hypothyroidism (CH) is one of the most common endocrinopathies in children and has potentially devastating neurologic and developmental consequences. The etiology and clinical manifestations of hypothyroidism in children differ from adults. And hence, pediatric medical care requires a detailed understanding of thyroid function and dysfunction in children. The perinatal risk factors include female sex, preterm birth, low birth weight, postmature birth, additional birth abnormalities, and being delivered in multiple births. In countries where newborn screening is practiced, CH is detected after birth through screening tests. It aids in determining the underlying cause, though some patients may be able to start treatment without these tests. Early detection and treatment prevent irreversible and permanent nervous system damage. Thus, in addition to exploring the development of CH, this article has also covered the epidemiological data, clinical aspects, and management stemming from pediatric hypothyroidism.

[Ectopic thyroid gland: clinical features and diagnostics in children]

BACKGROUND

BACKGROUND: The frequency of ectopia of thyroid gland among all types of dysgenesis varies from 30 to 70%, its most common localization is the root of the tongue. Otorhinolaryngologists, oncologists, pediatricians can take lingual ectopia for hypertrophy of the lingual tonsil or fibroma of the tongue root, which leads to unreasonable surgical treatment. Thyroid scintigraphy plays a key role in the diagnosis of ectopia.

AIM

AIM: To assess the etiological structure of congenital hypothyroidism (CH) and demonstrate the clinical course in patients with ectopic thyroid tissue in the root of the tongue.

MATERIALS AND METHODS

MATERIALS AND METHODS: A group of patients with CH was examined. All patients underwent neck ultrasound and radionuclide imaging. The examination was carried out against the background of the abolition of hormone replacement therapy for 14 days or before its initiation. Patients with ectopia in the root of the tongue underwent videofibrolaryngoscopy. Some patients underwent a genetic study with using genes panel of a panel of candidate genes responsible for the development of CH using the NGS method. The molecular genetic study was conducted to some patients, next-generation sequencing with the genes panel.

RESULTS

RESULTS: The study included 73 patients with primary CH aged from 2 weeks to 17.3 years: 69 children were diagnosed based on the results of neonatal screening, 4 children with thyroid ectopia were first examined older than 6 years. The median age of patients at the time of the examination was 6.9 years [4.8; 10.0]. By data of ultrasound aplasia was diagnosed in 47.9% of patients, one child had hemiagenesis and ectopic thyroid tissue of various localization was detected in 26.0% of  children. In 24.7% of children thyroid tissue was found in a typical location. Scintigraphy confirmed thyroid aplasia in 65.7% of children. Examination revealed various variants of ectopically located thyroid tissue in 31 children (42.4%): thyroid ectopia in the root of the tongue in 25 children (80.6%), ectopia in the sublingual region in 5 children (16.2%), double ectopia was detected in 1 child. The median level of TSH in newborns with ectopic thyroid gland was 124 IU/ml and was significantly lower than in children with aplasia — 219 IU/ml, p<0.05. On the other side the level of TG in children with ectopia was significantly higher than in children with aplasia — 37.12 ng/ml versus 0.82 ng/ml, p><0.05. CONCLUSION: Combination of two methods is the best diagnostic approach to determine the etiology of CH — ultrasound and scintigraphy studies compensates deficiencies of each other. Our study demonstrates the importance of scintigraphy in children with CH and patients with the formation of the root of the tongue and the anterior surface of the neck in order to avoid unnecessary removal of the thyroid gland. In case of confirmation of thyroid ectopia in the root of the tongue and in the absence of symptoms of obstruction or bleeding, it is recommended to refer the patient to an endocrinologist for conservative treatment. ><0.05. On the other side the level of TG in children with ectopia was significantly higher than in children with aplasia — 37.12 ng/ml versus 0.82 ng/ml, p< 0.05.

CONCLUSION

CONCLUSION: Combination of two methods is the best diagnostic approach to determine the etiology of CH — ultrasound and scintigraphy studies compensates deficiencies of each other. Our study demonstrates the importance of scintigraphy in children with CH and patients with the formation of the root of the tongue and the anterior surface of the neck in order to avoid unnecessary removal of the thyroid gland. In case of confirmation of thyroid ectopia in the root of the tongue and in the absence of symptoms of obstruction or bleeding, it is recommended to refer the patient to an endocrinologist for conservative treatment.

Thyroid Hemiagenesis: Narrative Review and Clinical Implications

Thyroid Hemiagenesis (THA) is an uncommon, congenital anomaly defined by the absence of one thyroid lobe with or without the isthmus. Reports suggest it may be found more often in regions endemic for hypothyroidism. Genetic abnormalities are thought to have a role based on findings in monozygotic twins. Most cases are sporadic, however familiar clusters have also been documented. It is found more frequently in females. A majority of patients report no symptoms and THA is found incidentally during investigations or intraoperatively. THA is usually associated with normal thyroid function, but it can present with thyroid hypofunction.

Since a majority of patients are asymptomatic, there are no specific recommendations for management. Ultrasound imaging and thyroid scintigraphy using technetium or iodine are useful in diagnosis. Its clinical importance occurs when the remnant thyroid lobe requires excision leading to the lifelong requirement for thyroxine supplementation.

Published English literature (Medline, PubMed, and Embase databases) was searched. Medical subject headings (MeSH) terms used were “thyroid hemiagenesis,” “one thyroid lobe,” and “thyroid aplasia”. Case reports, case series, and original articles were selected to provide a framework for this review.

Articles reviewed were published in the past 20 years. The association of THA with thyroid cancer was explored. In this group, the F:M ratio was 3.25:1. Left THA constituted 53% of cases, right THA in 29.4%, and isthmus absence in 17.6% of cases. Also, the authors investigated the link between THA and hyperparathyroidism, both left and right THA are seen in an equal number of cases in the hyperparathyroidism subgroup. In patients with THA and Grave’s disease, left THA was seen in a majority of cases (86.7%), while an equal number of left and right THA was observed in patients with Hashimoto’s thyroiditis. In addition, congenital abnormalities associated with THA were observed, the left THA was seen in 60% and right THA in 40% of cases of this subgroup.

The summative review provided a detailed insight into the epidemiology, aetiopathogenesis, genetics, symptomatology, diagnosis, and treatment for THA by combining findings and results from almost a hundred research papers from around the world. THA remains a poorly understood, often incidentally detected, abnormality in euthyroid patients undergoing investigations and treatment for other thyroid disorders.

Targeted Secondary Screening for Congenital Hypothyroidism in High-Risk Neonates: A 9 Year Review in a Large California Health Care System

Secondary screening for missed congenital hypothyroidism (CH) has been introduced sporadically, but its necessity and optimal strategy have not been recognized. We hypothesized that a simple clinical protocol (performed by a medical group without a governmental mandate) targeting infants at high risk for missed CH can identify cases. We performed a 9-year retrospective review of 338,478 neonates within a California health plan following the introduction of thyrotropin (TSH) secondary screening for neonates at high risk for missed CH due to very-low-birthweight (VLBW), hospitalized congenital heart disease (CHD), and same-sex multiples (SSM). Screening performance by day 60 of life was 95% successful for VLBW and >50% for CHD and SSM, leading to an additional 35% CH treated cases despite re-testing only 1.7% of the cohort. Infants with VLBW or CHD were 33 times more likely (190 times more likely for CHD with Down Syndrome) to receive treatment for CH than random infants diagnosed by primary screening (p < 0.001), and 92% of these infants were not found by primary newborn screening. Currently, permanent disease has been documented in 84% of CH by primary screening compared to 27% by secondary screening (p < 0.001). This targeted secondary screening program identifies and treats additional CH cases after TSH-only newborn screening.

The factors associated with transient hypothyroxinemia of prematurity

Background

Hypothyroxinemia is defined by low levels of thyroxine (T4) despite low or normal levels of thyroid-stimulating hormone (TSH). This study aimed to evaluate the factors associated with transient hypothyroxinemia of prematurity (THOP) in newborns admitted to the neonatal intensive care unit (NICU).

Method

This is a single center, retrospective, case-control study. Premature newborns, between 24 and 34 weeks of gestation, hospitalised between January 2014–December 2019 in Istanbul University-Cerrahpasa Faculty of Medicine NICU were analyzed through their medical records. Thyroid function tests were routinely performed between the 10th and 20th days of postnatal life and were evaluated according to the gestational age references. Thirty six possible associated factors (prenatal and postnatal parameters, medical treatments, clinical diagnoses and applications in NICU) were searched in the patient group with THOP (n = 71) and the control group with euthyroid prematures (n = 73). The factors for THOP were identified by univariate analysis, followed by multivariate analysis.

Results

Mean gestational ages of the study and the control groups were 29.7 ± 2.48 and 30.5 ± 2.30 weeks, respectively (p = 0.606). The birth weight, small for gestational age (SGA), intraventricular hemorrhage (IVH), congenital heart disease (CHD) were found to be the possible associated factors for THOP in the univariate analysis and CHD (p = 0.007, odds ratio [OR]:4.9, 95% confidence interval [CI]: 1.5–15.8), BW (p = 0.004, OR:0.999, 95% CI: 0.9–1.0) and SGA (p = 0.010, OR:4.6, 95% CI: 1.4–14.7) were found to be factors associated with THOP determined by univariate logistic regression analysis.

Conclusıons

Although some treatment practices might have had direct effects on pituitary–thyroid axis, related with the severity of the newborn clinical conditions, non of them was found to be a associated factor for THOP. However, CHD and SGA may be considered as associated factors with THOP detected in preterm infants.

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.

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.

Incidence of primary congenital hypothyroidism and relationship between diagnostic categories and associated malformations

PURPOSE

The incidence of primary congenital hypothyroidism (CH) has grown progressively and literature data indicate an association between CH and congenital malformations. The purpose of this study is to establish the current incidence of CH in the Italian Region of Piedmont and verify the relationship between CH diagnostic categories and associated malformations.

METHODS

The biochemical and clinical data of 105 newborns with CH diagnosed in the period January 2014 to December 2019 were analyzed.

RESULTS

The incidence of CH in the Italian Piedmont region in the 2014-2019 period increased to 1:1090. Thyroid dysgenesis was responsible for 47.6% (50/105) of all cases, with agenesis in 14.3% (15/105), while ectopia and hypoplasia in 23.8% (25/105) and 9.5% (10/105) of the cases, respectively; dyshormonogenesis defects were found in 52.4% (55/105) of cases. Congenital extra-thyroid anomalies were identified in 33/105 (31.4%) of newborns with CH and mainly involve the cardiac system (17/85, 16.1%), urogenital tract (7/85, 6.7%), gastrointestinal tract (5/105, 4.8%), and the musculoskeletal system (5/105, 4.8%). The highest rate of malformations was observed in patients with thyroid agenesis and dyshormonogenesis, respectively, in 53.5% and 36.4% of cases, while in the presence of thyroid ectopia and hypoplasia, the rate was 12% and 20%, respectively, (p = 0.03).

CONCLUSION

In the Italian region of Piedmont, the incidence of primary CH has been increased over time, with a variation in the percentage of the different forms of CH. Congenital malformations, especially affecting the cardiovascular, urogenital, gastrointestinal, and musculoskeletal systems, seem to be mainly associated with thyroid agenesis or defects in hormonogenesis.

Screening of Congenital Hypothyroidism in North-East Romania. Benefits and Messages for Further Improvement

Background

If not diagnosed at birth, congenital hypothyroidism (CH) can cause deleterious, irreversible neurodevelopmental sequels. The importance of thyroid newborn screening (NBS) is therefore well established.

Objective

To evaluate the efficacy of NBS for CH in North-East Romania.

Methods

Retrospective, descriptive study involving 271662 newborns screened between 2010 and 2019 for CH and phenylketonuria in maternities from six Romanian North-Eastern counties by measuring neonatal TSH (neoTSH) in the whole blood extracted from the heel between days 3 and 5 after birth. Values found higher than a cut-off level of 10 mIU/L were followed by serum evaluation of TSH and fT4 for the confirmation of CH. Thyroid ultrasound was further performed at children found with CH.

Results

NeoTSH was found elevated in 417 newborns, but CH was subsequently confirmed in only 57 cases (1/4766 newborns). Mean age at the time when diagnosis was communicated was of 37.2 ± 15 days (between 9 and 157 days). Mean age when therapy was started was of 44.2 ± 17.9 days (between 13 and 160 days) with a mean delay of one week from diagnosis (between 0 and 62 days). Thyroid ultrasound revealed athyreosis in only 3 cases, atrophic thyroid gland in other 10 cases, whereas the thyroid was described as present in the remnant 44 cases. The number of first year follow-up visits greatly varied from 0 to 5, with an average of 2.

Conclusions

NBS allowed rapid diagnosis of CH in North East Romania. The communication of diagnosis to families and therapy onset were however often delayed. Diagnosis and therapy onset before the age of two weeks, as well as a tighter follow-up should be assured by the healthcare system. Etiological diagnosis should be more accurate, for a better prognosis of disease severity, as well as the possibility of genetic advice in selected cases.

Postnatal Cardiac Development and Regenerative Potential in Large Mammals

The neonatal capacity for cardiac regeneration in mice is well studied and has been used to develop many potential strategies for adult cardiac regenerative repair following injury. However, translating these findings from rodents to designing regenerative therapeutics for adult human heart disease remains elusive. Large mammals including pigs, dogs, and sheep are widely used as animal models of humans in preclinical trials of new cardiac drugs and devices. However, very little is known about the fundamental cardiac cell biology and the timing of postnatal cardiac events that influence cardiomyocyte proliferation in these animals. There is emerging evidence that external physiological and environmental cues could be the key to understanding cardiomyocyte proliferative behavior. In this review, we survey available literature on postnatal development in various large mammal models to offer a perspective on the physiological and cellular characteristics that could be regulating cardiomyocyte proliferation. Similarities and differences between developmental milestones, cardiomyocyte maturational events, as well as environmental cues regulating cardiac development, are discussed for various large mammals, with a focus on postnatal cardiac regenerative potential and translatability to the human heart.

How can the occurrence of delayed elevation of thyroid stimulating hormone in preterm infants born between 35 and 36 weeks gestation be predicted?

Objective

We evaluated frequency and risk factors of delayed TSH elevation (dTSH) and investigated follow-up outcomes in the dTSH group with venous TSH (v-TSH) levels of 6–20 mU/L according to whether late preterm infants born at gestational age (GA) 35–36 weeks had risk factors.

Methods

The medical records of 810 neonates (414 boys) born at Seoul National University Hospital who had a normal neonatal screening test (NST) and underwent the first repeat venous blood test at 10–21 days post birth were reviewed.

Results

Seventy-three (9.0%) neonates showed dTSH, defined as a v-TSH level ≥6.0 mU/L, 12 of whom (1.5%) were started on levothyroxine medication. A multivariate-adjusted model indicated that a low birth weight (LBW <2,000 g), a congenital anomaly, and exposure to iodine contrast media (ICM) were significant predictors for dTSH (all p < 0.05). Among these 73 dTSH infants, all 5 infants with TSH levels ≥20 mU/L began levothyroxine medication, and 6 of 16 infants with v-TSH levels of 10–20 mU/L were indicated for levothyroxine, regardless of coexisting risk factors. However, only 1 of 52 infants with v-TSH levels of 6–10 mU/L who had a congenital anomaly was indicated for levothyroxine. All healthy late preterm infants, including LBW and multiple births, with v-TSH levels of 6–10 mU/L exhibited normal thyroid function.

Conclusions

dTSH was detected in 9.0% and levothyroxine was indicated in 1.5% of infants born at GA 35–36 weeks, particularly those with a LBW, a congenital anomaly, or history of ICM exposure. Either levothyroxine or retesting is indicated for late preterm neonates with TSH levels ≥10 mU/L regardless of risk factors. If healthy preterm neonates show v-TSH levels of 6–10 mU/L, a second repeat test may not be necessary; however, further studies are required to set a threshold for retesting.

Neonatal effects of thyroid diseases in pregnancy and approach to the infant with increased TSH: Turkish Neonatal and Pediatric Endocrinology and Diabetes Societies consensus report

Thyroid functions in the fetus and newborn carry importance in terms of the baby's health and development of the central nervous system. Maternaliodine deficiency, exposure to iodine, thyroid diseases (Hashimoto thyroiditis, Graves') and drugs used by the mother affect thyroid functions in the fetus. Reflections of these effects are observed immediately after delivery. Investigation of the mother in terms of thyroid diseases during pregnancy, recognition and appropriate assessment of the required conditions, screening of all newborns in the first days of life in terms of congenital hypothyroidism, timely and appropriate evaluation of the screening results, early diagnosis and appropriate treatment of cases of congenital hypothyroidism, assessment and management of cases of transient thyroid hormone disorders and close monitoring of the thyroid functions and development of patients in whom treatment has been initiated with a diagnosis of hypothyroidism are crucial in terms of developmental outcomes of the babies who have thyroid function disorders or hypothyroidism. This guideline was written with the objective of guiding pediatricians, neonatologists and pediatric endocrinologists in the issue of assessment, diagnosis and management of thyroid function disorders and thyroid diseases concerning the fetus and baby during gestation and neonatal period.

Rectal Atresia and Congenital Hypothyroidism: An Association or Coincidence?

Rectal atresia is a rare anorectal malformation, and its association with other anomalies is even more rare. This study presents a unique case of co-twin in which the surviving newborn male underwent surgery due to rectal atresia. Newborn screening tests identified congenital hypothyroidism. The surgical treatment consisted of three stages and thyroid hormones were replaced.

Role of Jagged1-Notch pathway in thyroid development

The zebrafish thyroid gland shows a unique pattern of growth. Despite the lack of a compact gland, the zebrafish thyroid tissue originates from the pharyngeal endoderm and the main genes involved in its patterning and early development are conserved between zebrafish and mammals. In recent years, the research has been focused to the search of novel candidate genes and environmental factors underlying congenital hypothyroidism. Among these, it has been demonstrated that the Notch signalling plays a central role during zebrafish thyroid development. In this review, we will provide an overview of the current knowledge of the distinct roles of the Notch signalling and of the jag1a and jag1b ligands during the different phases of thyroid organogenesis. Furthermore, we will discuss the role of JAG1 variants in congenital thyroid defects.

Clinical course of infants with congenital heart disease who developed thyroid dysfunction within 100 days

PURPOSE

We investigated the clinical course of infants with congenital heart disease (CHD) who experienced thyroid dysfunction within 100 days of birth.

METHODS

We performed retrospective medical reviews of 54 CHD patients (24 male patients) who underwent a thyroid function test (TFT) between January 2007 and July 2016. Data were collected on birth history, diagnosis of CHD, underlying chromosomal or genetic abnormalities, medication history, surgery, ventilator care, and exposure to iodine contrast media (ICM). Results of neonatal screening tests (NSTs) and TFTs were reviewed.

RESULTS

A total of 36 patients (29 transient, 7 permanent) showed thyroid dysfunction. Among the seven patients with permanent hypothyroidism, three had an underlying syndrome, three showed abnormal NST results, and one was admitted to the intensive care unit for macroglossia and feeding cyanosis. We found that infants with transient thyroid dysfunction had a lower birth weight and were more commonly exposed to thyroid disrupting medication and/or ICM. However, these risk factors were not significant. A total of 8 patients with a history of ICM exposure showed thyroid dysfunction. Excluding 3 patients with elevated thyroid stimulating hormone before ICM exposure, 5 patients recovered from transient thyroid dysfunction.

CONCLUSIONS

We observed thyroid dysfunction in two-thirds of CHD infants (53.7% transient, 13.0% permanent) who had risk factors and received TFT screening within 100 days, despite normal NSTs. Further studies with larger sample sizes are required to revise the criteria for TFT screening in CHD infants.

Transient hypothyroidism in the newborn: to treat or not to treat

Transient congenital hypothyroidism (CH) refers to a temporary deficiency of thyroid hormone identified after birth, with low thyroxine (T4) and elevated thyrotropin (TSH), which later recovers to improved thyroxine production, typically in first few months of infancy. Approximately 17% to 40% of children diagnosed with CH by newborn screening (NBS) programs were later determined to have transient hypothyroidism. Causes of transient CH are prematurity, iodine deficiency, maternal thyrotropin receptor blocking antibodies, maternal intake of anti-thyroid drugs, maternal or neonatal iodine exposure, loss of function mutations and hepatic hemangiomas. The classic clinical symptoms and signs of CH are usually absent immediately after birth in vast majority of infants due to temporary protection from maternal thyroxine. NBS has been largely successful in preventing intellectual disability by early detection of CH by performing thyroid function tests in infants with abnormal screening results. In this review we present the evidence for decision making regarding treatment vs. withholding treatment in infants with transient CH and present a rational approach to identifying transient CH based on American Academy of Pediatrics (AAP) recommendation.

Hypothyroidism in Infants With Congenital Heart Disease Exposed to Excess Iodine

Thyroid hormone is critical for neonatal brain development, and even transient hypothyroidism can cause adverse neurocognitive outcomes. Infants exposed to excess iodine are at risk of developing hypothyroidism, especially those with congenital heart disease (CHD), because they are routinely exposed to excess iodine from intravenous iodinated contrast media and topical antiseptics. The aim of the present study was to identify the proportion of neonates with CHD exposed to iodine who developed hypothyroidism and to identify the associated risk factors. This was a retrospective study of neonates undergoing cardiac catheterization at Boston Children's Hospital during a 3-year period, some of whom also underwent cardiac surgery. Hypothyroidism was defined as an elevated thyroid-stimulating hormone level (>20 mIU/L at 24 to 96 hours of age and >15 mIU/L at >96 hours of age by heel-stick sampling and >9.1 mIU/L at 1 to 20 weeks of age by serum testing). Multivariate logistic regression was performed to predict the odds of developing hypothyroidism. Hypothyroidism was diagnosed incidentally in 46 of 183 infants (25%) with CHD after iodine exposure. Controlling for baseline cardiac risk, postnatal age, and gestational age, we found a fourfold increase in odds of developing hypothyroidism in neonates with serum creatinine >0.9 mg/dL and a fourfold increase in those who underwent more than three procedures. Hypothyroidism in neonates with CHD exposed to excess iodine is associated with multiple procedures and impaired renal function. Routine serial monitoring of thyroid function in these neonates is warranted. Future studies should examine the association between hypothyroidism and neurocognitive function in this population.

Congenital urogenital abnormalities in children with congenital hypothyroidism

Background: Congenital hypothyroidism (CH), as one of the most common congenital endocrine disorders, may be significantly associated with congenital malformations. This study investigates urogenital abnormalities in children with primary CH (PCH).

Methods: This case-control study was conducted on 200 children aged three months to 1 year, referred to Amir-Kabir Hospital, Arak, Iran. One hundred children with PCH, as the case group, and 100 healthy children, as the control group, were selected using convenient sampling. For all children, demographic data checklists were filled, and physical examination, abdomen and pelvic ultrasound and other diagnostic measures (if necessary) were performed to evaluate the congenital urogenital abnormalities including anomalies of the penis and urethra, and disorders and anomalies of the scrotal contents.

Results: Among 92 (100%) urogenital anomalies diagnosed, highest frequencies with 37 (40.2%), 26(28.2%) and 9 (9.7%) cases including hypospadias, Cryptorchidism, and hydrocele, respectively. The frequency of urogenital abnormalities among 32 children with PCH, with 52 cases (56.5%) was significantly higher than the frequency of abnormalities among the 21 children in the control group, with 40 cases (43.4%). (OR=2.04; 95%CI: 1.1-3.6; p=0.014).

Conclusion: Our study demonstrated that PCH is significantly associated with the congenital urogenital abnormalities. However, due to the lack of evidence in this area, further studies are recommended to determine the necessity of conducting screening programs for abnormalities of the urogenital system in children with CH at birth.

Mutations in proteasome-related genes are associated with thyroid hemiagenesis

PURPOSE

Human thyroid development is a complex and still unexplained process. Thyroid hemiagenesis is a congenital anomaly, where one of the thyroid lobes fails to develop. In the majority of patients with thyroid hemiagenesis, the genetic background remains unknown. The aim of the study was to search for novel genetic contributors to the etiology of thyroid hemiagenesis.

METHODS

A cohort of 34 sporadic patients diagnosed with thyroid hemiagenesis and one three-generation family were subjected to comprehensive genomic examination. Initially, targeted screening of associated transcription factors, known to be linked to thyroid development, was performed. As a next step, genomic examinations were applied using high-resolution microarrays, whereas for the thyroid hemiagenesis family, additionally the whole exome sequencing was performed.

RESULTS

Screening of transcription factors revealed no causative mutations in the studied cohort. Genomic examinations revealed the presence of four recurrent defects (three deletions and one duplication) affecting highly conservative proteasome genes PSMA1, PSMA3, and PSMD3. In a thyroid hemiagenesis family a splice site mutation in a proteasome gene PSMD2 (c.612T > C cDNA.1170T > C, g.3271T > C) was found in both affected mother and daughter.

CONCLUSIONS

Our results shed a new light on etiology of thyroid hemiagenesis, so far suspected to be linked only to mutations in the genes directly involved in the thyroid development. We demonstrated, for the first time, that genomic alterations in proteasome-associated genes co-occur in patients presenting this developmental anomaly.

Endocrinologic Diseases in Pediatric Cardiac Intensive Care

OBJECTIVES

The objectives of this review are to discuss the pathophysiology, clinical impact and treatment of hyperglycemia, and disturbances in thyroid and adrenal function prior to and following cardiac surgery in children.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSIONS

Disturbances in glucose metabolism and thyroid and adrenal function are common in critically ill children with cardiac disease and in particular in children undergoing cardiac surgery for complex congenital heart disease. An understanding of the pathophysiology, clinical impact and treatment of these disturbances is essential for the management of these at risk patients.

Role of thyroid hormones in ventricular remodeling

Cardiac remodeling includes alterations in molecular, cellular, and interstitial systems contributing to changes in size, shape, and function of the heart. This may be the result of injury, alterations in hemodynamic load, neurohormonal effects, electrical abnormalities, metabolic changes, etc. Thyroid hormones (THs) serve as master regulators for diverse remodeling processes of the cardiovascular system-from the prenatal period to death. THs promote a beneficial cardiomyocyte shape and improve contractility, relaxation, and survival via reversal of molecular remodeling. THs reduce fibrosis by decreasing interstitial collagen and reduce the incidence and duration of arrhythmias via remodeling ion channel expression and function. THs restore metabolic function and also improve blood flow both by direct effects on the vessel architecture and decreasing atherosclerosis. Optimal levels of THs both in the circulation and in cardiac tissues are critical for normal homeostasis. This review highlights TH-based remodeling and clinically translatable strategies for diverse cardiovascular disorders.

Congenital anomalies of kidney and upper urinary tract in children with congenital hypothyroidism; a case-control study

INTRODUCTION

Congenital hypothyroidism (CH) may be significantly associated with congenital malformations. However, there is little evidence on the relationship between renal and urinary tract anomalies and CH.

OBJECTIVES

The aim of this study was to compare the renal and upper urinary tract anomalies in children with and without primary CH (PCH).

PATIENTS AND METHODS

This case-control study was conducted on 200 children aged 3 months to 1 year, referring to Amir-Kabir hospital, Arak, Iran. One hundred children with PCH, as the case group, and 100 children without CH, as the control group, were selected. For all children, ultrasonography and other diagnostic measures (if necessary) were performed to evaluate renal and upper urinary tract anomalies (ureter and bladder).

RESULTS

The frequency of renal and upper urinary tract anomalies among 43 children with primary CH, with 83 cases (72.8%), was significantly higher than the frequency of anomalies among the 19 children in the control group, with 31 cases (27.1%) (OR = 3; CI 95%: 1.6-5.4; P = 0.001). Among the anomalies studied, only the differences in frequency of uretero-pelvic junction obstruction (UPJO) (OR = 6; CI 95%: 1.3-28; P = 0.018) and hydronephrosis (OR = 22; CI 95%: 5-95; P = 0.001) was significant between the two groups.

CONCLUSION

Our study demonstrated that PCH is significantly associated with the frequency of congenital anomalies of the kidneys and upper urinary tracts. However, further studies are recommended to determine the necessity of conducting screening programs for anomalies of the kidneys and urinary tract in children with CH at birth.

Heterogeneous phenotype in children affected by non-autoimmune hypothyroidism: an update

BACKGROUND

In the last decades, a higher incidence of congenital hypothyroidism (CH) has been recorded in Italy (1:1940) and worldwide, mainly due to the shift to lower screening TSH cutoffs. Although CH can also be caused by dysgenetic defects, most CH cases have recently been found to be more frequently associated with functional defects of an in situ thyroid gland. Although the clinical phenotype is milder with high prevalence of transient forms, some cases eventually prove to be permanent.

RESULTS

Possible explanations of the raised incidence of CH are ethnic modifications of the screened population and the increasing incidence of preterm birth and multiple pregnancies. These findings are important in terms of public health and standardization of screening programmes for special at-risk categories such as preterms, acutely ill term neonates, low birth weight and very low birth weight infants, and newborns with specific drug exposure. Other environmental factors have contributed to the increased incidence of hypothyroidism, including thyroid disrupting chemicals, iodine supply (excess/deficiency), and drugs interfering with thyroid function. Finally, an increased prevalence of hypothyroidism has been documented in obese children and patients with syndromic forms (Williams, Down, Turner, pseudohypoparathyroidism). The clinical and molecular phenotype of patients with CH will be better defined thanks to novel genetic approach based on the systematic analysis of a panel of genes (TSHR, DUOX2, DUOXA, TPO, PDS, TG, NKX2.1, JAG1, GLIS3, FOXE1, PAX-8).

CONCLUSIONS

This review summarizes significant advances in the epidemiology and aetiology of non-autoimmune hypothyroidism, with a focus on thyroid dysfunction in preterm infants.

Guidelines for Mass Screening of Congenital Hypothyroidism (2014 revision)

Purpose of developing the guidelines: Mass screening for congenital hypothyroidism started in 1979 in Japan, and the prognosis for intelligence has been improved by early diagnosis and treatment. The incidence was about 1/4000 of the birth population, but it has increased due to diagnosis of subclinical congenital hypothyroidism. The disease requires continuous treatment, and specialized medical facilities should make a differential diagnosis and treat subjects who are positive in mass screening to avoid unnecessary treatment. The Guidelines for Mass Screening of Congenital Hypothyroidism (1998 version) were developed by the Mass Screening Committee of the Japanese Society for Pediatric Endocrinology in 1998. Subsequently, new findings on prognosis and problems in the adult phase have emerged. Based on these new findings, the 1998 guidelines were revised in the current document (hereinafter referred to as the Guidelines). Target disease/conditions: Primary congenital hypothyroidism. Users of the Guidelines: Physician specialists in pediatric endocrinology, pediatric specialists, physicians referring patients to pediatric practitioners, general physicians, laboratory technicians in charge of mass screening, and patients.

A single nucleotide polymorphism associated with isolated cleft lip and palate, thyroid cancer and hypothyroidism alters the activity of an oral epithelium and thyroid enhancer near FOXE1

Three common diseases, isolated cleft lip and cleft palate (CLP), hypothyroidism and thyroid cancer all map to the FOXE1 locus, but causative variants have yet to be identified. In patients with CLP, the frequency of coding mutations in FOXE1 fails to account for the risk attributable to this locus, suggesting that the common risk alleles reside in nearby regulatory elements. Using a combination of zebrafish and mouse transgenesis, we screened 15 conserved non-coding sequences for enhancer activity, identifying three that regulate expression in a tissue specific pattern consistent with endogenous foxe1 expression. These three, located -82.4, -67.7 and +22.6 kb from the FOXE1 start codon, are all active in the oral epithelium or branchial arches. The -67.7 and +22.6 kb elements are also active in the developing heart, and the -67.7 kb element uniquely directs expression in the developing thyroid. Within the -67.7 kb element is the SNP rs7850258 that is associated with all three diseases. Quantitative reporter assays in oral epithelial and thyroid cell lines show that the rs7850258 allele (G) associated with CLP and hypothyroidism has significantly greater enhancer activity than the allele associated with thyroid cancer (A). Moreover, consistent with predicted transcription factor binding differences, the -67.7 kb element containing rs7850258 allele G is significantly more responsive to both MYC and ARNT than allele A. By demonstrating that this common non-coding variant alters FOXE1 expression, we have identified at least in part the functional basis for the genetic risk of these seemingly disparate disorders.

Thyroid dyshormonogenesis and associated non-thyroidal anomalies in a tertiary care hospital in India

BACKGROUND

Dyshormonogenetic goiter refers to familial goiters owing to an inherited defect in the metabolism of thyroid hormones.

METHODS

19 patients with clinical and biochemically proven hypothyroidism (low T3, FT4 and high TSH) were recruited for the study. All patients were subjected to (i) ultrasound of the neck to rule out thyroid dysgenesis and (ii) technetium-99m radionuclide thyroid scintigraphy and a perchlorate discharge test (PDT). Extrathyroidal malformations were identified by clinical ultrasound (USG) examination of the abdomen and pelvis and by echocardiography.

RESULTS

Out of 19 patients with elevated thyroid uptakes on technetium-99m thyroid scintigraphy, 12 (63%) had a positive PDT and 7 patients (37%) had a negative PDT. All patients were subjected to abdominopelvic USG and echocardiography. Out of 12 patients with a positive PDT, 5 (42%) had associated extrathyroid malformations, 2 had urogenital malformations, and cardiac abnormalities on echocardiography were present in 2 patients (17%). One patient (8%) had features of dysmorphism in the form of a high-arched palate, low-set ears and microcephaly.

CONCLUSION

Congenital hypothyroidism due to dyshormogenesis is associated with a high prevalence of extrathyroidal malformations and needs to be managed as early as possible to ensure normal neurocognitive development of the children affected.

Sublingual thyroid ectopy: similarities and differences with Kallmann syndrome

Permanent primary congenital hypothyroidism (CH), the commonest cause of preventable intellectual disability, is due to defects in the embryonic development of the thyroid in the vast majority of cases. These defects are collectively called thyroid dysgenesis. The thyroid may be absent (athyreosis) but, more commonly, a sublingual thyroid ectopy without lateral lobes, is the only thyroid tissue present. Such an ectopy presumably results from an arrest in the downward migration of the median anlage. Thyroid ectopy almost always occurs in a sporadic fashion. However, first-degree relatives are affected more often than chance alone would predict. On the other hand, almost all reported monozygotic twin pairs are discordant for thyroid ectopy. Current research is aimed at reconciling these contradictory epidemiological data. We propose a two-hit mechanism associating a germline predisposing factor with another genetic or epigenetic alteration within the ectopic thyroid tissue itself or, as in some forms of Kallmann syndrome, in the structures surrounding the thyroid during embryogenesis. Thyroid ectopy, a model for sporadic congenital malformations in humans, is also associated with congenital heart disease, and molecular mechanisms common to thyroid and heart development are being unraveled.

European Society for Paediatric Endocrinology consensus guidelines on screening, diagnosis, and management of congenital hypothyroidism

OBJECTIVE

The aim was to formulate practice guidelines for the diagnosis and management of congenital hypothyroidism (CH).

EVIDENCE

A systematic literature search was conducted to identify key articles relating to the screening, diagnosis, and management of CH. The evidence-based guidelines were developed with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion.

CONSENSUS PROCESS

Thirty-two participants drawn from the European Society for Paediatric Endocrinology and five other major scientific societies in the field of pediatric endocrinology were allocated to working groups with assigned topics and specific questions. Each group searched the literature, evaluated the evidence, and developed a draft document. These papers were debated and finalized by each group before presentation to the full assembly for further discussion and agreement.

RECOMMENDATIONS

The recommendations include: worldwide neonatal screening, approaches to assess the cause (including genotyping) and the severity of the disorder, the immediate initiation of appropriate L-T4 supplementation and frequent monitoring to ensure dose adjustments to keep thyroid hormone levels in the target ranges, a trial of treatment in patients suspected of transient CH, regular assessments of developmental and neurosensory functions, consulting health professionals as appropriate, and education about CH. The harmonization of diagnosis, management, and routine health surveillance would not only optimize patient outcomes, but should also facilitate epidemiological studies of the disorder. Individuals with CH require monitoring throughout their lives, particularly during early childhood and pregnancy.

Comprehensive genotyping and clinical characterisation reveal 27 novel NKX2-1 mutations and expand the phenotypic spectrum

BACKGROUND

NKX2-1 encodes a transcription factor with large impact on the development of brain, lung and thyroid. Germline mutations of NKX2-1 can lead to dysfunction and malformations of these organs. Starting from the largest coherent collection of patients with a suspected phenotype to date, we systematically evaluated frequency, quality and spectrum of phenotypic consequences of NKX2-1 mutations.

METHODS

After identifying mutations by Sanger sequencing and array CGH, we comprehensively reanalysed the phenotype of affected patients and their relatives. We employed electrophoretic mobility shift assay (EMSA) to detect alterations of NKX2-1 DNA binding. Gene expression was monitored by means of in situ hybridisation and compared with the expression level of MBIP, a candidate gene presumably involved in the disorders and closely located in close genomic proximity to NKX2-1.

RESULTS

Within 101 index patients, we detected 17 point mutations and 10 deletions. Neurological symptoms were the most consistent finding (100%), followed by lung affection (78%) and thyroidal dysfunction (75%). Novel symptoms associated with NKX2-1 mutations comprise abnormal height, bouts of fever and cardiac septum defects. In contrast to previous reports, our data suggest that missense mutations in the homeodomain of NKX2-1 not necessarily modify its DNA binding capacity and that this specific type of mutations may be associated with mild pulmonary phenotypes such as asthma. Two deletions did not include NKX2-1, but MBIP, whose expression spatially and temporarily coincides with NKX2-1 in early murine development.

CONCLUSIONS

The high incidence of NKX2-1 mutations strongly recommends the routine screen for mutations in patients with corresponding symptoms. However, this analysis should not be confined to the exonic sequence alone, but should take advantage of affordable NGS technology to expand the target to adjacent regulatory sequences and the NKX2-1 interactome in order to maximise the yield of this diagnostic effort.

European Society for Paediatric Endocrinology consensus guidelines on screening, diagnosis, and management of congenital hypothyroidism

OBJECTIVE

The aim was to formulate practice guidelines for the diagnosis and management of congenital hypothyroidism (CH).

EVIDENCE

A systematic literature search was conducted to identify key articles relating to the screening, diagnosis, and management of CH. The evidence-based guidelines were developed with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion.

CONSENSUS PROCESS

Thirty-two participants drawn from the European Society for Paediatric Endocrinology and five other major scientific societies in the field of pediatric endocrinology were allocated to working groups with assigned topics and specific questions. Each group searched the literature, evaluated the evidence, and developed a draft document. These papers were debated and finalized by each group before presentation to the full assembly for further discussion and agreement.

RECOMMENDATIONS

The recommendations include: worldwide neonatal screening, approaches to assess the cause (including genotyping) and the severity of the disorder, the immediate initiation of appropriate L-T4 supplementation and frequent monitoring to ensure dose adjustments to keep thyroid hormone levels in the target ranges, a trial of treatment in patients suspected of transient CH, regular assessments of developmental and neurosensory functions, consulting health professionals as appropriate, and education about CH. The harmonization of diagnosis, management, and routine health surveillance would not only optimize patient outcomes, but should also facilitate epidemiological studies of the disorder. Individuals with CH require monitoring throughout their lives, particularly during early childhood and pregnancy.

Congenital hypothyroidism and the importance of universal newborn screening

Congenital hypothyroidism (CH) is one of the most common preventable causes of mental retardation in children. Early diagnosis and treatment prevent the devastating outcome of mental retardation. Clinical features of CH are subtle and are not evident early in the neonatal period. Therefore, universal newborn screening (NS) is effective in detecting CH and implementing early treatment. This article reviews the current literature regarding the epidemiology, etiology, classification, clinical features, diagnosis of primary CH, and the management of abnormal newborn screen as well as treatment and prognosis of primary CH and outlines the importance of universal newborn screening in preventing mental retardation.

Thyroid disease in children: part 1: State-of-the-art imaging in pediatric hypothyroidism

Hypothyroidism, defined as inadequate production of thyroid hormone, can be secondary to various underlying abnormalities in the pediatric population. Most frequently, hypothyroidism is related to structural abnormalities of the gland (dysgenesis), particularly in the neonatal population. However, other etiologies including intrinsic biochemical (dyshormonogenesis) and autoimmune abnormalities, as well as other rare causes, must be considered. Imaging is required to differentiate among the various etiologies of hypothyroidism and can be helpful in guiding therapy. This review aims to present an organized approach to hypothyroidism in the pediatric population, and assist the imager in guiding patient care.

The Italian screening program for primary congenital hypothyroidism: actions to improve screening, diagnosis, follow-up, and surveillance

The Italian screening program for primary congenital hypothyroidism (CH) is an integrated system including neonatal screening, diagnosis, treatment, follow-up, and nationwide surveillance of the disease. The aim of the Italian screening program for CH is to identify not only babies with severe permanent CH (core target), but also babies with mild persistent and transient forms of CH who could have a benefit from an early replacement therapy (secondary target). In the last years, despite the important results obtained in terms of standardization of screening and follow-up procedures, it has become clear the need of optimizing the program in order to harmonize the screening strategy and the screening procedures among Regions, and to improve the diagnostic and therapeutic approach in all affected infants. On the basis of available guidelines, the experience of the Italian screening and clinical reference centers, and the knowledge derived from the nation-wide surveillance activity performed by the Italian National Registry of Infants with CH, the Italian Society for Pediatric Endocrinology and Diabetology together with the Italian Society for the Study of Metabolic Diseases and Neonatal Screening and the Italian National Institute of Health promoted actions aimed at improving diagnosis, treatment, follow-up and surveillance of CH in our country. In this paper the most important actions to improve the Italian screening program for CH are described.

Congenital hypothyroidism after assisted reproductive technology in Japan: comparison between multiples and singletons, 2005-2009

Background

The relationship between congenital hypothyroidism (CH) and multiple pregnancy has not been fully studied in Japan.

Methods

Complete nationwide data of assisted reproductive technology (ART) in Japan from 2005 to 2009 presented by the Japan Society of Obstetrics and Gynecology, which include information on CH and birth defects were used for analyses. Diseases were reclassified according to the International Classification of Diseases, tenth edition (ICD-10, 2003 version). The relative risk (RR) and 95% confidence interval (CI) of the incidence rate for CH was calculated with singletons as the reference group. Additional birth defects with CH were examined. The probandwise concordance rate of multiples and recurrence risk ratio were calculated.

Results

There were 18 patients with CH, consisting of 12 singletons and 6 multiples. The incidence rates of CH per 1,000 live births in singletons and multiples are 0.14 (=12/87,145) and 0.31 (=6/19,533), respectively. The incidence rate was more than twofold higher in multiple births than in singleton births, but the difference was not statistically significant (RR=2.2, 95% CI 0.8–5.9). Additional birth defects were present in three patients with CH (17%=3/18). The multiples were affected by other birth defects more frequently (33%=2/6) than the singletons (8%=1/12). The six multiple-births patients were derived from one concordant twin pair, which consisted of two twin patients; three discordant twin pairs, which consisted of three twin patients; and one discordant triplets set, which consisted of one triplet patient. Thus, the probandwise concordance rate was 33.3% (=2/(2+4)). The estimated recurrence risk ratio was 1976 (for the total ART population) or 609 (for the Japanese general population).

Conclusions

CH was more frequent in multiples compared to singletons. A higher percentage of additional birth defects was also observed in multiples compared to singletons. The familial aggregation of CH was suggested.

The ambiguous role of NKX2-5 mutations in thyroid dysgenesis

NKX2-5 is a homeodomain-containing transcription factor implied in both heart and thyroid development. Numerous mutations in NKX2-5 have been reported in individuals with congenital heart disease (CHD), but recently a select few have been associated with thyroid dysgenesis, among which the p.A119S variation. We sequenced NKX2-5 in 303 sporadic CHD patients and 38 families with at least two individuals with CHD. The p.A119S variation was identified in two unrelated patients: one was found in the proband of a family with four affected individuals with CHD and the other in a sporadic CHD patient. Clinical evaluation of heart and thyroid showed that the mutation did not segregate with CHD in the familial case, nor did any of the seven mutation carriers have thyroid abnormalities. We tested the functional consequences of the p.A119S variation in a cellular context by performing transactivation assays with promoters relevant for both heart and thyroid development in rat heart derived H10 cells and HELA cells. There was no difference between wildtype NKX2-5 and p.A119S NKX2-5 in activation of the investigated promoters in both cell lines. Additionally, we reviewed the current literature on the topic, showing that there is no clear evidence for a major pathogenic role of NKX2-5 mutations in thyroid dysgenesis. In conclusion, our study demonstrates that p.A119S does not cause CHD or TD and that it is a rare variation that behaves equal to wildtype NKX2-5. Furthermore, given the wealth of published evidence, we suggest that NKX2-5 mutations do not play a major pathogenic role in thyroid dysgenesis, and that genetic testing of NKX2-5 in TD is not warranted.

Congenital anomalies in infant with congenital hypothyroidism

OBJECTIVE

Congenital hypothyroidism is characterized by inadequate thyroid hormone production in newborn infants. Many infants with CH have co-occurring congenital malformations. This is an investigation on the frequency and types of congenital anomalies in infants with congenital hypothyroidism born from May 2006-2010 in Hamadan, west province of Iran.

METHODS

The Iranian neonatal screening program for congenital hypothyroidism was initiated in May 2005. This prospective descriptive study was conducted in infants diagnosed with congenital hypothyroidism being followed up in Pediatric Endocrinology Clinic of Besat Hospital, a tertiary care centre in Hamadan. Cases included all infants with congenital hypothyroidism diagnosed through newborn screening program or detected clinically. Anomalies were identified by clinical examination, echocardiography, and X-ray of the hip during the infant's first year of life.

RESULTS

A total of 150 infants with biochemically confirmed primary congenital hypothyroidism (72 females and 78 males) were recruited during the period between May 2006-2010. Overall, 30 (20%) infants had associated congenital anomalies. The most common type of anomaly was Down syndrome. Seven infants (3.1%) had congenital cardiac anomalies such as: ASD (n=3), VSD (n=2), PS (n =1), PDA (n=1). Three children (2.6%) had developmental dysplasia of the hip (n=3).

CONCLUSION

The overall frequency of Down syndrome, cardiac malformation and other birth defect was high in infants with CH. This reinforces the need to examine all infants with congenital hypothyroidism for the presence of associated congenital anomalies.

High prevalence of congenital hypothyroidism in Isfahan: Do familial components have a role?

Background:

Despite elimination of iodine deficiency, the rates of both permanent and transient congenital hypothyroidism (CH) in our study were higher than the comparable worldwide rates, which emphasize the major role of genetic factors in the pathogenesis of CH and many studies in this regard confirm this possibility.

Materials and Methods:

In this review, we report all studies that established during CH screening program regarding familial and genetic component of the disease.

Results:

Although we could not entirely ignore the possible role of environmental and autoimmune factors in the development and function of thyroid gland, our findings strongly suggest the role of genetic factors as dominant etiologic factor in CH.

Conclusion:

The studies support the existence of a familial component of CH involving dominant genetic predisposition factors with a low penetrance. Considering the polygenic/multifactorial basis of CH, they suggest the possible involvement of other unknown genes in the pathogenesis of the disease, which may also follow non-Mendelian pattern of inheritance.

Detection and treatment of congenital hypothyroidism

Congenital hypothyroidism is the most frequent endocrine disorder in neonates. Controversy exists regarding the necessity to adjust current screening programs to also diagnose patients with central hypothyroidism or those with mild forms of congenital hypothyroidism, who have high TSH levels but normal T(4) and normal T(3) levels (also known as 'subclinical hypothyroidism'). Thyroid hormone replacement should start as soon as the diagnosis is confirmed by measurement of elevated TSH and low serum thyroid hormone levels. Further diagnostic approaches, such as ultrasonography, scintigraphy and measurement of thyroglobulin levels, to determine the subtype of congenital hypothyroidism, should not delay initiation of treatment. Recommendations regarding the initial dosage of levothyroxine vary considerably, and no general accepted guideline exists with regards to initial dosage or optimal time point for dose adjustment according to biochemical parameters. More than 30 years after the introduction of the first neonatal screening programs, mental retardation can be prevented in the majority of children (>90%) with congenital hypothyroidism if therapy is commenced within the first 2 weeks of life, making neonate screening for this disorder the most successful population-based screening test in pediatrics.

Screening for mutations in the ISL1 gene in patients with thyroid dysgenesis

CONTEXT

Congenital hypothyroidism (CH) is a common endocrine disorder with an incidence of 1:3000- 4000 newborns. In 80-85% of cases, CH is caused by defects in thyroid organogenesis, resulting in absent, ectopically located, and/or severely reduced gland, all conditions indicated as "thyroid dysgenesis" (TD). A higher prevalence of congenital heart diseases has been documented in children with CH compared to the general population. This association suggests a possible pathogenic role of genes involved in both heart and thyroid development. Among these, it can be included Isl1, a transcription factor containing a LIM homeodomain that is expressed in both thyroid and heart during morphogenesis.

OBJECTIVE

In the present study, we investigate the role of ISL1 in the pathogenesis of TD.

SETTINGS AND PATIENTS

By single stranded conformational polymorphism, we screened for mutations the entire ISL1 coding sequence in 96 patients with TD and in 96 normal controls.

RESULTS

No mutations have been found in patients and controls.

CONCLUSION

Our data indicate that, despite the relevant role of ISL1 in thyroid and heart morphogenesis, mutations in its coding region are not associated with TD in our group of patients.

Congenital hypothyroidism

Congenital hypothyroidism (CH) occurs in approximately 1:2,000 to 1:4,000 newborns. The clinical manifestations are often subtle or not present at birth. This likely is due to trans-placental passage of some maternal thyroid hormone, while many infants have some thyroid production of their own. Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice. On examination, common signs include myxedematous facies, large fontanels, macroglossia, a distended abdomen with umbilical hernia, and hypotonia. CH is classified into permanent and transient forms, which in turn can be divided into primary, secondary, or peripheral etiologies. Thyroid dysgenesis accounts for 85% of permanent, primary CH, while inborn errors of thyroid hormone biosynthesis (dyshormonogeneses) account for 10-15% of cases. Secondary or central CH may occur with isolated TSH deficiency, but more commonly it is associated with congenital hypopitiutarism. Transient CH most commonly occurs in preterm infants born in areas of endemic iodine deficiency. In countries with newborn screening programs in place, infants with CH are diagnosed after detection by screening tests. The diagnosis should be confirmed by finding an elevated serum TSH and low T4 or free T4 level. Other diagnostic tests, such as thyroid radionuclide uptake and scan, thyroid sonography, or serum thyroglobulin determination may help pinpoint the underlying etiology, although treatment may be started without these tests. Levothyroxine is the treatment of choice; the recommended starting dose is 10 to 15 mcg/kg/day. The immediate goals of treatment are to rapidly raise the serum T4 above 130 nmol/L (10 ug/dL) and normalize serum TSH levels. Frequent laboratory monitoring in infancy is essential to ensure optimal neurocognitive outcome. Serum TSH and free T4 should be measured every 1-2 months in the first 6 months of life and every 3-4 months thereafter. In general, the prognosis of infants detected by screening and started on treatment early is excellent, with IQs similar to sibling or classmate controls. Studies show that a lower neurocognitive outcome may occur in those infants started at a later age (> 30 days of age), on lower l-thyroxine doses than currently recommended, and in those infants with more severe hypothyroidism.

High prevalence of associated birth defects in congenital hypothyroidism

Aim. To identify dysmorphic features and cardiac, skeletal, and urogenital anomalies in patients with congenital hypothyroidism. Patients and Methods. Seventeen children with congenital primary hypothyroidism were recruited. Cause for congenital hypothyroidism was established using ultrasound of thyroid and ^99mTc radionuclide thyroid scintigraphy. Malformations were identified by clinical examination, echocardiography, X-ray of lumbar spine, and ultrasonography of abdomen. Results. Ten (59%) patients (6 males and 4 females) had congenital malformations. Two had more than one congenital malformation (both spina bifida and ostium secundum atrial septal defect). Five (29%) had cardiac malformations, of whom three had only osteum secundum atrial septal defect (ASD), one had only patent ductus arteriosus (PDA), and one patient had both ASD and PDA. Seven patients (41%) had neural tube defects in the form of spina bifida occulta. Conclusion. Our study indicates the need for routine echocardiography in all patients with congenital hypothyroidism.

The Italian National Register of infants with congenital hypothyroidism: twenty years of surveillance and study of congenital hypothyroidism

All the Italian Centres in charge of screening, diagnosis, and follow-up of infants with congenital hypothyroidism participate in the Italian National Registry of affected infants, which performs the nationwide surveillance of the disease. It was established in 1987 as a program of the Health Ministry and is coordinated by the Istituto Superiore di Sanità. The early diagnosis performed by the nationwide newborn screening programme, the prompt treatment and the appropriate clinical management of the patients carried out by the Follow-up Centres, and the surveillance of the disease performed by the National Register of infants with congenital hypothyroidism are the components of an integrated approach to the disease which has been successfully established in our country.

The aim of the Register is to monitor efficiency and effectiveness of neonatal screening, to provide disease surveillance and to allow identification of possible aetiological risk factors for the disease. During the past twenty years the active and continuous collaboration between the Register and the Italian Screening and Follow up Centres for Congenital Hypothyroidism allowed to perform a standardization of screening procedures and considerable improvements in the time at starting treatment and in the dose of therapy. Furthermore, the large amount and the high quality of information collected in the Register provided a unique opportunity for research into the disease. This because data collected in the Register are highly representative as referred to the entire Italian population with congenital hypothyroidism. The results derived from the epidemiological studies performed in these years, by using the Register database, contributed to deepen the knowledge of congenital hypothyroidism, to start identifying the most important risk factors for the disease, and to orient molecular studies aimed at identifying new genes involved in the aetiology of this condition.

Early thyroid development requires a Tbx1-Fgf8 pathway

The thyroid develops within the pharyngeal apparatus from endodermally-derived cells. The many derivatives of the pharyngeal apparatus develop at similar times and sometimes from common cell types, explaining why many syndromic disorders express multiple birth defects affecting different structures that share a common pharyngeal origin. Thus, different derivatives may share common genetic networks during their development. Tbx1, the major gene associated with DiGeorge syndrome, is a key player in the global development of the pharyngeal apparatus, being required for virtually all its derivatives, including the thyroid. Here we show that Tbx1 regulates the size of the early thyroid primordium through its expression in the adjacent mesoderm. Because Tbx1 regulates the expression of Fgf8 in the mesoderm, we postulated that Fgf8 mediates critical Tbx1-dependent interactions between mesodermal cells and endodermal thyrocyte progenitors. Indeed, conditional ablation of Fgf8 in Tbx1-expressing cells caused an early thyroid phenotype similar to that of Tbx1 mutant mice. In addition, expression of an Fgf8 cDNA in the Tbx1 domain rescued the early size defect of the thyroid primordium in Tbx1 mutants. Thus, we have established that a Tbx1->Fgf8 pathway in the pharyngeal mesoderm is a key size regulator of mammalian thyroid.

TTF-2/FOXE1 gene polymorphisms in Sicilian patients with permanent primary congenital hypothyroidism

Thyroid transcription factor-2 (TTF-2/FOXE1) is a polyalanine domain protein that regulates thyroid embryogenesis, but very few patients with permanent primary congenital hypothyroidism (pCH) harbor germline mutations of this or other transcription factors that are involved in thyroid development that might explain the etiology of pCH. Variations within the polyalanine tract are found in a variety of genes and are often reported in association with malformation syndromes; pCH is frequently associated with thyroid malformations and extra-thyroidal malformations. Therefore, in this study we investigated whether alanine (Ala) length polymorphisms and non-polymorphic mutations of the TTF-2 gene in pCH patients might be involved in the pathogenesis of pCH. The entire coding region of the TTF-2 gene was analyzed in 57 Sicilian patients and 142 healthy controls. We found that the homozygous Ala14 polymorphism (Ala14/14) was less frequent in the pCH group than in the controls. In contrast, significantly more pCH patients than controls harbored the Ala16 polymorphism (Ala16/16 and Ala14/16). However, neither the Ala14/14 nor the Ala16 polymorphism was related to extra-thyroidal malformations. Two of the 57 patients carried Ala11/14 and Ala12/14, and one Ala14/14 patient also had the silent polymorphism 387 C/T (Leu129Leu). Other than known polymorphic variants we found no mutation in the TTF-2 gene. Therefore, this study demonstrates that mutations in the TTF-2 gene are rare in pCH patients and suggests that variations in the length of the Ala-tract could at least partially explain the etiology of pCH but not that of extra-thyroidal malformations.

Clinical significance of heterozygous carriers associated with compensated hypothyroidism in R450H, a common inactivating mutation of the thyrotropin receptor gene in Japanese

Loss-of-function mutations in the thyrotropin receptor (TSHR) gene were described as a syndrome characterized by thyroid hyposensivity to biologically active TSH, ranging from euthyroid to severe hypothyroidism. In Japanese, a common mutation in the TSHR gene is R450H, which demonstrated moderately impaired receptor function. We studied six subjects of Japanese origin whose major abnormality was persistent hyperthyrotropinemia by genetic sequence analysis of the TSHR gene. Three subjects were homozygous for the R450H mutation, whereas the three remaining subjects were single heterozygous. Homozygous subjects displayed mild hypothyroidism confirmed by moderately elevated basal TSH levels and excessive TSH response to TRH administration. Heterozygous subjects also demonstrated fully or partially compensated hypothyroidism, but less severe than that of homozygous subjects. More frequent involvement of the R450H mutation in the TSHR gene in Japanese was identified. In addition, a good correlation between phenotype and genotype was demonstrated in respect to biochemical analysis and drug dosage. Our observations showed clinical significance of heterozygosity associated with compensated hypothyroidism in spite of only mildly impaired receptor function.