Thyroid abnormalities by ultrasonography in neonates with congenital hypothyroidism

Congenital Hypothyroidism: Screening and Management

ABSTRACT

Untreated congenital hypothyroidism (CH) leads to intellectual disabilities. Prompt diagnosis by newborn screening (NBS) leading to early and adequate treatment results in grossly normal neurocognitive outcomes in adulthood. However, NBS for hypothyroidism is not yet established in all countries globally. Seventy percent of neonates worldwide do not undergo NBS.The initial treatment of CH is levothyroxine, 10 to 15 mcg/kg daily. The goals of treatment are to maintain consistent euthyroidism with normal thyroid-stimulating hormone and free thyroxine in the upper half of the age-specific reference range during the first 3 years of life. Controversy remains regarding detection of thyroid dysfunction and optimal management of special populations, including preterm or low-birth weight infants and infants with transient or mild CH, trisomy 21, or central hypothyroidism.Newborn screening alone is not sufficient to prevent adverse outcomes from CH in a pediatric population. In addition to NBS, the management of CH requires timely confirmation of the diagnosis, accurate interpretation of thyroid function testing, effective treatment, and consistent follow-up. Physicians need to consider hypothyroidism in the face of clinical symptoms, even if NBS thyroid test results are normal. When clinical symptoms and signs of hypothyroidism are present (such as large posterior fontanelle, large tongue, umbilical hernia, prolonged jaundice, constipation, lethargy, and/or hypothermia), measurement of serum thyroid-stimulating hormone and free thyroxine is indicated, regardless of NBS results.

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.

[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.

Ultrasound findings of the thyroid gland in children and adolescents

Ultrasonography (US) is an important diagnostic tool in evaluating thyroid diseases in pediatric patients. This pictorial essay reviews the application of various ultrasound techniques such as B-Mode ultrasound and color Doppler, elastography and contrast enhanced ultrasound (CEUS) in children and adolescents in various thyroid pathologies including congenital thyroid abnormalities, diffuse thyroid diseases (DTD), focal thyroid lesions and thyroid malignancy.

Intrathyroidal Thymus (Incidentaloma) Mimicking Thyroid Neoplasia in DICER1 Syndrome

INTRODUCTION

With the use of ultrasonography for the evaluation of thyroid and nonthyroid neck diseases, the incidental discovery of previously unsuspected thyroid nodules/nonpalpable lesions has increased. Intrathyroidal thymus arises due to aberrant thymic migration during embryogenesis. It is thought to be rare, fulfils the classiccriteria for diagnosis of an incidentaloma and it can be mistaken for a thyroid nodule. Multinodular goiter is the main endocrine manifestation of DICER1 syndrome, a tumor predisposition syndrome. Careful thyroid examination including ultrasound is thus necessary for DICER1 syndrome patients.

CASE REPORT

A 4-year-old prepubertal boy was referred to the pediatric endocrinology department following an earlier diagnosis of pleuropulmonary blastoma (PPB) type III, which is a hallmark component of DICER1 syndrome. The patient underwent surgery followed by chemotherapy. Genetic analysis identified a germline DICER1 pathogenic variant (c.2062C>T, p.R688*)in the child and in 5 relatives. A second somatic DICER1 RNase IIIb hotspot mutation(c.5438A>G, p.E1813G) was identified in DNA extracted from the proband's PPB. He had no goiter on clinical examination, but a heterogenous, well-delineated, avascular, solid and hypoechogenic lesion with pseudomicrocalcifications was observed in the right lobe (4.1 × 3.1 × 2.6 mm), suggestive of thyroid neoplasia. Diagnostic work-up and a 3-year follow-up excluded thyroid neoplasia and confirmed the diagnosis of an intrathyroid benign thymic lesion.

DISCUSSION AND CONCLUSION

This case exemplifies that thyroid incidentalomas in DICER1 syndrome patients should be viewed with great suspicion, but that not all thyroid disorders are indeed DICER1-related in these patients.

Thyroid imaging study in children with suspected thyroid dysgenesis

PURPOSE

Thyroid dysgenesis is one of the most common causes of permanent congenital hypothyroidism. Thyroid ultrasonography or scan is used to detect thyroid dysgenesis. We analyzed the sensitivity and specificity of thyroid ultrasonography and scan in diagnosing thyroid dysgenesis to determine the clinical utility of each thyroid imaging method.

METHODS

Sixty-one patients younger than 7 years of age were investigated via thyroid scan. Nineteen patients who were initially interpreted as having thyroid dysgenesis, such as ectopia, hemiagenesis, or aplasia, by thyroid scan were included in the study. Clinical characteristics and findings of a thyroid imaging study were reviewed.

RESULTS

Initially, thyroid scan results were interpreted as ectopia (n=9), hemiagenesis (n=1), and nonvisualization (n=9). In contrast, the results of thyroid ultrasonography were normal thyroid gland (n=5), ectopia (n=6), and hypoplasia (n=8). After reviewing the results of both studies, final imaging diagnoses were as follows: normal thyroid gland (n=5), hemiagenesis (n=1), ectopia (n=9) including 2 dual ectopy, hypoplasia (n=3), and aplasia (n=1). Thyroid ultrasonography showed higher sensitivity and specificity in detecting presence of normal thyroid gland. Thyroid scan was better to detect ectopia. Among 8 patients who were initially interpreted as having hypoplasia by ultrasonography, 4 were confirmed as ectopia and one as aplasia.

CONCLUSION

This study showed that thyroid ultrasonography is useful as the first-line imaging study to detect normal-sized eutopic thyroid gland. Thyroid scan should be performed to investigate the presence of ectopia if hypoplasia or aplasia is suspected by ultrasonography.

Determination of thyroid volume in infants with suspected congenital hypothyroidism-the limitations of both subjective and objective evaluation

Objective:

To compare two methods of assessing gland size on thyroid ultrasound in newborn infants with suspected congenital hypothyroidism (CH).

Methods:

Images from infants with eutopic glands referred between 2007 and 2013 were evaluated blind by two sets of observers. Subjective gland size was categorised as small, borderline-small, normal, borderline-large and large. Objective gland volume, calculated as the sum of each lobe using the prolate ellipsoid formula (length x width x depth x π/6), was put into corresponding categories: <0.8, 0.81–1.0, 1.1– <2.2, 2.2–2.4 and >2.4 ml, derived from normative Scottish data.

Results:

Of 36 infants, permanent CH was present in 17, transient CH in 17, status uncertain in 2. Mean (SD) intraobserver error for thyroid volume measurement was 0.11 (0.23) ml [8.3%]. Subjective assessment by two observers was discordant in only four (10.8%) infants. However, subjective vs objective evaluation was discordant in 14 (39%). Eight (three permanent, five transient CH) had large glands subjectively but normal glands objectively; and six (four transient CH) had normal glands subjectively but small glands objectively. The former infants all showed a single flattened curve to the anterior thyroid margin, giving an impression of bulkiness. Gland shape was normal in the latter infants.

Conclusion:

Neither subjective nor objective evaluation predicts permanent vs transient CH. Altered gland shape may confound both methods, and undermine use of the conventional formula for measuring lobe volume.

Advances in knowledge:

Until more refined methods are available for assessing thyroid size, both subjective and objective evaluation are recommended in CH.

Pediatric thyroid ultrasound: a radiologist's checklist

Ultrasonography (US) is the imaging method of choice for evaluating the pediatric thyroid gland, complemented by scintigraphy and thyroid function tests, especially when evaluating children with suspected congenital hypothyroidism, goiter, infectious or autoimmune diseases, or neoplasm. Diagnostic considerations in newborns with congenital hypothyroidism mainly include dysgenesis, dyshormonogenesis, transient hypothyroidism and central (hypophyseal) hypothyroidism. The midline of the neck should be scrutinized for thyroid tissue from the floor of the mouth to the thoracic inlet. Cystic and echogenic ultimobranchial remnants should not be misinterpreted as orthotopic thyroid tissue. Diffuse thyroid diseases affect older children; these comprise Hashimoto and Graves diseases and infectious thyroiditis and exhibit features similar to those in adults. It is important to note that the diffuse sclerosing variant of papillary thyroid cancer can complicate thyroiditis and should not be confused with Hashimoto disease. In children with solid nodules the threshold for fine-needle aspiration biopsy or surgery should be lower compared to adults because of a higher likelihood of malignancy compared with adults. Biopsy should be considered in nodules with suspicious ultrasonographic features, even when smaller than 1 cm. Adult classification systems of thyroid nodules, although useful, are not sufficient to safely discriminate the nodules' likelihood of malignancy in children. We describe key sonographic findings and suggest a standard checklist that might be considered while performing and interpreting thyroid US in neonates and children.

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.

Normative Data of Thyroid Gland Volume in South Indian Neonates and Infants

OBJECTIVE

To establish normative ultrasound data for thyroid gland volume in South Indian neonates and infants and compare with abnormal sonological features of thyroid in congenital hypothyroidism (CH) to explore thyroid ultrasound utility as a supportive screening tool to newborn screening programs for early detection of CH.

METHODS

In view of impact of geo ethnic factors, varying growth velocities and body mass indices of human population worldwide, specific regional, age and gender related reference data for thyroid gland size and volume are vital. This study was an offshoot of ICMR pilot New Born Screening (NBS) project for CH. Formula used for thyroid volume estimation was ellipsoidal formula D1 x D2 x D3 × 0.523. It was a prospective observational study. The neonates who screened negative for Thyroid Stimulating Hormone (TSH) with repeat normal serum TSH and free thyroxine were selected. One hundred fifty seven infants were enrolled which included 99 boys and 58 girls. The study population included children in age groups from 3 d to 1 y six months.

RESULTS

Data analysis was done by descriptive method and unpaired t test. Mean thyroid volume was 0.26 ml with 0.27 ml in boys and 0.24 ml in girls. Statistically significant "p value" was noted in single lobe measurements among boys and girls.

CONCLUSIONS

Thyroid gland volume normative data play a key role in evaluation of thyroid sonological abnormalities in CH and there is effective utility of ultrasound as a supportive diagnostic and prognostic screening tool for early detection of CH.

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

OBJECTIVE

Results of the screening of disease causative mutations in congenital hypothyroidism (CH) vary significantly, depending on the sequence strategy, patients' inclusion criteria and bioinformatics. The objective was to study the molecular basis of severe congenital hypothyroidism, using the next generation sequencing (NGS) and the recent guidelines for assessment of sequence variants.

DESIGN

243 patients with CH (TSH levels at neonatal screening or retesting greater than 90 mU/l) and 56 control subjects were included in the study.

METHODS

A custom NGS panel targeting 12 CH causative genes was used for sequencing. The sequence variants were rated according to American College of Medical Genetics and Genomics (ACMG) guidelines.

RESULTS

In total, 48 pathogenic, 7 likely pathogenic and 57 variants of uncertain significance were identified in 92/243 patients (37.9%), while 4 variants of uncertain significance were found in 4/56 control subjects (7.1%). 13.1% (12/92) of the cases showed variants in 'thyroid dysgenesis' (TD) genes: TSHR, n = 6; NKX2-1, n = 2; NKX2-5, n = 1; PAX8, n = 3. The variants in 'dyshormonogenesis' (DH) genes were found in 84.8% (78/92) of cases: TPO, n = 30; DUOX2, n = 24; TG, n = 8; SLC5A5, n = 3; SLC26A4, n = 6; IYD, n = 1. 8 patients showed oligonenic variants. The majority of variants identified in DH genes were monoallelic.

CONCLUSIONS

In contrast to earlier studies demonstrating the predominance of TD in severe CH, the majority of variants identified in our study were in DH genes. A large proportion of monoallelic variants detected among DH genes suggests that non-mendelian mechanisms may play a role in the development of CH.

Mutation analysis of the NKX2.5 gene in Iranian pediatric patients with congenital hypothyroidism

BACKGROUND

The embryonic development of the thyroid gland is regulated by the expression of several candidate genes which are related to congenital hypothyroidism. These genes include the numerous critical thyroid transcription factors such as NKX2.1, NKX2.5, FOXE1, and PAX8. The molecular analysis of these loci will be essential to the explanation of the participation of these transcription activators in the etiology of hypothyroidism. Among them, the role of NKX2.5 is important during the early thyroid morphogenesis and in controlling thyroidal cell differentiation and migration. Importantly, NKX2.5 change nucleotides are recognized to be central to the genesis of congenital hypothyroidism.

METHODS

A case-control study was conducted in 65 unrelated patients, diagnosed with primary congenital hypothyroidism and all of them were diagnosed according to the clinical presentations of thyroid hypoplasia and without cardiovascular defects. Mutational screening of the entire NKX2-5 coding sequence was performed in a cohort of pediatric patients by PCR-SSCP and direct sequencing.

RESULTS

We identified two known variations 73C>T (R25C) and 63A>G (E21E) in patients with thyroid hypothyroidism. Both of them are located in conserved region of the gene and previously reported in cases with thyroid dysgenesis and congenital heart defects. There was a significance association between 63A>G variation with primary hypothyroidism (p=0.003).

CONCLUSIONS

These SNPs are probably related to thyroid hypoplasia because the allele frequency of the 63A>G polymorphism was significantly different in patients and controls and also R25C variation not observed in healthy cases.

Elevated levels of Wnt signaling disrupt thymus morphogenesis and function

All vertebrates possess a thymus, whose epithelial microenvironment is essential for T cell development and maturation. Despite the importance of the thymus for cellular immune defense, many questions surrounding its morphogenesis remain unanswered. Here, we demonstrate that, in contrast to the situation in many other epithelial cell types, differentiation of thymic epithelial cells (TECs) proceeds normally in the absence of canonical Wnt signaling and the classical adhesion molecule E-cadherin. By contrast, TEC-intrinsic activation of β-catenin-dependent Wnt signaling blocks the morphogenesis of the thymus, and overexpression of a secreted Wnt ligand by TECs dominantly modifies the morphogenesis not only of the thymus, but also of the parathyroid and thyroid. These observations indicate that Wnt signaling activity in the thymus needs to be precisely controlled to support normal TEC differentiation, and suggest possible mechanisms underlying anatomical variations of the thymus, parathyroid and thyroid in humans.

Timing of thyroid ultrasonography in the etiological investigation of congenital hypothyroidism

OBJECTIVES

To describe the findings of thyroid ultrasonography (T-US), its contribution to diagnose congenital hypothyroidism (CH) and the best time to perform it.

SUBJECTS AND METHODS

Forty-four patients with CH were invited to undergo T-US and 41 accepted. Age ranged from 2 months to 45 years; 23 patients were females. All were treated with L-thyroxine; 16 had previously undergone scintigraphy and 30 had previous T-US, which were compared to current ones.

RESULTS

At the current T-US, the thyroid gland was not visualized in its normal topography in 10 patients (24.5%); 31 T-US showed topic thyroid, 17 with normal or increased volume due to probable dyshormonogenesis, 13 cases of hypoplasia and one case of left-lobe hemiagenesis. One patient had decreased volume due to central hypothyroidism. Scintigraphy scans performed 3-4 years earlier showed 100% agreement with current results. Comparisons with previous T-US showed concordant results regarding thyroid location, but a decrease in current volume was observed in eight due to the use of L-thyroxine, calling the diagnosis of hypoplasia into question.

CONCLUSIONS

The role of T-US goes beyond complementing scintigraphy results. It allows inferring the etiology of CH, but it must be performed in the first months of life. An accurate diagnosis of CH will be attained with molecular study and the T-US can guide this early assessment, without therapy withdrawal.

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.

Congenital Hypothyroidism: Long-Term Experience with Early and High Levothyroxine Dosage

AIM

To assess the management and outcome of the congenital hypothyroidism (CH) patients followed at our institution since the introduction of systemic neonatal screening for CH.

STUDY DESIGN

The records of 139 CH patients referred to our center between 1978 and 2014 were retrospectively reviewed. Biochemical and imaging data at diagnosis, initial treatment and growth were analyzed.

RESULTS

111 patients had thyroid dysgenesis (64 ectopy, 46 athyreosis and 1 hypoplasia) and 28 patients had a gland in situ (17 dyshormonogenesis/goiter and 11 normal-sized gland). Levothyroxine treatment was initiated at a median age of 11 days with a mean dose of 11.4 µg/kg/day. Compared to those with ectopy, patients with athyreosis had higher thyroid-stimulating hormone (TSH) and lower thyroxine at diagnosis as well as more delayed bone maturation. Between 1978 and 2014, we observed earlier treatment and earlier TSH normalization. Birth auxology was slightly above the mean of the reference population. Growth at 1 and 6 years and school progression at 11 years were similar to those of the reference population.

CONCLUSION

Ectopy is the commonest cause of CH. Children with CH treated early with a mean levothyroxine dose of 11.4 µg/kg/day had a median TSH of 3.07 mU/l at 1 month of age and normal growth.

Thyroid Imaging in Infants

Congenital hypothyroidism is the most common preventable cause of mental retardation. It is important to know the cause of each patient's thyroid dysfunction to foresee the course of therapy and outcomes. Imaging methods, such as ultrasound and thyroid scan, help determine the anatomy and function of the thyroid gland. Although thyroid scan is considered superior in detecting ectopic thyroid tissue, ultrasound is able to detect the presence of thyroid tissue not otherwise visualized in 15% of patients.

Dual thyroid ectopia-role of thyroid scintigraphy and neck ultrasonography

Ectopic thyroid tissue (ETT) is a rare developmental anomaly of the thyroid tissue where the thyroid gland is not located in its usual position. Dual thyroid ectopia is far rarer. This case of a 5-year-old euthyroid girl with thyroglossal cyst was planned for surgery. Presurgical ultrasonography (USG) of the neck followed by thyroid scintigraphy was performed. There was absent normal thyroid gland with single ETT in neck swelling on USG. However, thyroid scintigraphy revealed two ectopic foci of thyroid tissue; one was corresponding to neck swelling, and other was superior to it at the base of the tongue along with absent eutopic thyroid gland. The repeat neck USG could demonstrate the same. The present case emphasizes that, if the thyroid gland is not visible by USG; ETT should be evaluated with thyroid scintigraphy in case of thyroid dysgenesis.

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.

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.

Diagnostic and predictive value of ultrasound and isotope thyroid scanning, alone and in combination, in infants referred with thyroid-stimulating hormone elevation on newborn screening

OBJECTIVE

To determine the diagnostic and predictive value of ultrasound and radioisotope scans of the thyroid, alone and in combination, during a single visit after initial referral by the screening laboratory with thyroid-stimulating hormone (TSH) elevation.

STUDY DESIGN

Retrospective blind review of ultrasound and radioisotope images followed by final diagnosis based on clinical features, biochemistry, imaging, and molecular genetic study.

RESULTS

Infants (n = 97; 61 female) with median birthweight 3.38 kg (range 2.04-4.86) and gestation 40 weeks (range 33-42), underwent successful dual thyroid ultrasound and technetium-99m pertechnetate radioisotope scan in a single center. Combined scanning at the initial visit resulted in a correct final diagnosis in 79 of 97 (81%) cases. One patient was misdiagnosed initially as having athyreosis as the result of delayed radioisotope scan and the diagnosis of ectopia made later on diagnostic challenge. The specificity/sensitivity for radioisotope scan and for ultrasound was as follows: 100%/97% and 100%/55% for ectopia (n = 39); 81%/100% and 54%/100% for athyreosis (n = 18); and 89%/90% and 80%/95% for dyshormonogenesis (n = 20). Neither modality, alone or in combination, predicted final diagnosis in eutopic glands due to hypoplasia (n = 4), transient TSH elevation (n = 12), and status still uncertain (n = 4).

CONCLUSION

More than 80% of newborn infants with TSH elevation can be diagnosed correctly on initial imaging with combined radioisotope scan and ultrasound. Ultrasound cannot reliably detect thyroid ectopia. Radioisotope scan, especially if performed late, may show no uptake despite the presence of a eutopic gland.

The role of scintigraphy and ultrasound in the imaging of neonatal hypothyroidism: 5-year retrospective review of single-centre experience

INTRODUCTION

Congenital hypothyroidism (CH), as indicated by an elevation of capillary thyroid-stimulating hormone (TSH) at newborn screening, is a preventable cause of mental retardation with varying aetiology; it can be transient or permanent. Radionuclide assessment is currently the gold standard for imaging CH. This study aimed to (i) review the different scintigraphic patterns and correlate them with TSH levels/patient outcomes, (ii) assess the role of sonography in neonates with apparent agenesis as indicated by scintigraphy and (iii) develop a diagnostic investigative algorithm.

METHODS

The technetium thyroid scans of 83 consecutive patients (49 females, average age 32 days) with CH scanned between 2005 and 2009 were retrospectively reviewed. Two nuclear medicine physicians blinded to the clinical details interpreted the scans in consensus. Scintigram appearances were categorised into five groups. Patients scintigraphically diagnosed with thyroid agenesis were evaluated with ultrasound. TSH values and scintigraphic and sonographic findings were correlated with patients' final diagnosis.

RESULTS

Based on scintigraphy, 14, 13 and 19 patients out of 83 were assessed as having normal thyroid sites with normal, increased and decreased uptake, respectively. Twenty-two of 83 patients had no uptake, and 15 of 83 patients had ectopic uptake. Higher median TSH levels were seen in no-uptake and ectopic uptake subgroups. Eighteen of 22 patients with no uptake were evaluated with ultrasound. Three of the 18 patients had a normal thyroid gland, and three of 18 patients had a hypoplastic thyroid.

CONCLUSION

Scintigram findings in patients with congenital hypothyroidism fall into five major categories, which have therapeutic implications (lifelong thyroxine in agenesis versus trial of stopping thyroxine in other subgroups). Sonographic demonstration of thyroid tissue in patients scintigraphically diagnosed with thyroid agenesis has major management implications.

Imaging the thyroid in children

Color Doppler Ultrasounds (CDU) and Thyroid Scanning (TS) have much improved in recent years and offer a likely diagnosis of the disorder and its main subtypes. This especially applies when diagnosing permanent or transient causes of congenital hypothyroidism (CH), where dual imaging has proven to be more informative than single scanning. Though both isotopes have acceptable performances, the use of (123)I appears more advisable, since it more accurately identifies the various aetiologies of CH and probably has better dosimetric characteristics than (99m)Tc. Detailed dual imaging patterns are presented in connection with most of the underlying mechanisms explaining CH, thyroid dysgenesis (75%) and dyshormonogenesis (20%). Imaging of thyroid autoimmunity, of immunogenic thyrotoxicosis and of thyroid autonomy, is helped by CDU but most often requires a quantified (123)I-TS (molecular imaging). We finally show the interest of CDU to sort suspicious nodule and present the new TIRADS scoring system.

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.

Optimising outcome in congenital hypothyroidism; current opinions on best practice in initial assessment and subsequent management

Congenital hypothyroidism (CH), usually of the primary and permanent variety, is an eminently preventable cause of growth retardation and mental handicap whose outlook has been transformed by newborn screening, usually involving the measurement of capillary thyroid stimulating hormone (TSH). Severe primary CH, due for example to athyreosis, may result in subtle cognitive, behavioural and sensori-motor deficits, but the extent to which these can be offset by optimal postnatal diagnosis and management remains uncertain. This is because the available adult follow-up data reflect the outcome of previous management in the 1970's and 1980's, and also because the accurate neuro-psychological assessment of children is difficult, particularly in the preschool population. There is an urgent need to develop new consensus guidelines and to ensure that the children managed according to such guidelines are systematically and prospectively assessed so that good quality outcome data become available. In this review, key recommendations in the management of CH include: screening at day 3 so that severely affected infants can begin treatment within the first 10 days of life; setting the TSH referral cut-off at 8-10 mU/L; adopting a disciplined diagnostic algorithm to evaluate referred cases, with measurement of venous free thyroxine (T4), TSH and thyroglobulin combined with dual ultrasound and radioisotope imaging; initial treatment with a T4 dose of 50 μg daily in infants weighing ≥ 2.5 kg and 15 μg/kg/day in infants weighing < 2.5 kg followed by weekly review until thyroid function is normalised; and maintenance of free T4 levels between 15-26 pmol/L and TSH between 0.5-5 mU/L thereafter to avoid both under- and overtreatment.

Ultrasound for primary imaging of congenital hypothyroidism

OBJECTIVE

The purpose of this study was to retrospectively evaluate the use of sonography as the primary imaging modality for congenital hypothyroidism (CH).

MATERIALS AND METHODS

From our regional registry, we reviewed the cases of patients for whom either sonography or (99m)Tc-pertechnetate scanning was performed for CH between 2003 and 2010. Ultrasound studies were reviewed for presence, size, echotexture, vascularity, and location of the thyroid gland. Technetium-99m-pertechnetate scans were evaluated for the presence and location of the thyroid gland. The ultrasound studies were compared with the (99m)Tc-pertechnetate scans. We assessed the use of ultrasound as the primary imaging modality for the evaluation of CH.

RESULTS

We identified the cases of 124 patients (89 girls, 35 boys). Ultrasound studies were available for 121 patients, and (99m)Tc-pertechnetate studies for 62 patients. Three patients were examined only by (99m)Tc-pertechnetate scanning. The final imaging results were normal location with normal size or diffuse enlargement of the thyroid gland (n = 47), sublingual thyroid gland (n = 49), agenesis (n = 18), hypoplasia (n = 8), and hemiagenesis (n = 2). Compared with (99m)Tc-pertechnetate scanning, ultrasound had high (100%) specificity and low (44%) sensitivity for detection of sublingual thyroid gland.

CONCLUSION

We suggest using ultrasound as the primary imaging modality for guiding the treatment of children with CH, potentially decreasing radiation exposure and cost.

Solid ectopic cervical thymus in neonates with thyroid agenesis

We report a series of ectopic thymus glands as detected by sonography in infants with thyroid agenesis. The patients were children who underwent nuclear medicine and sonography for congenital hypothyroidism. Of the 12 patients with a diagnosis of thyroid agenesis over a 5-year period, 4 (33%) were shown to have ectopic thymic tissue. Although a cervical ectopic thymus has been previously reported, there is very little discussion of it occurring in conjunction with thyroid agenesis. This case series highlights the importance of recognition of ectopic thymic tissue when examining for thyroid tissue in the setting of congenital hypothyroidism.

Pitfalls in the diagnosis of thyroid dysgenesis by thyroid ultrasonography and scintigraphy

OBJECTIVES

We aimed to investigate the reliability of thyroid ultrasonography (US) and scintigraphy in determining the type of thyroid dysgenesis (TD).

METHODS

The study included 82 children (8.0±5.6 years) with a diagnosis of TD by thyroid scintigraphy with (99m)Tc and/or US. The patients were re-evaluated 6.0±5.1 years after the diagnosis. Thyroid US was performed in all cases, regardless of the previous US imaging. Scintigraphy images performed at the time of diagnoses (n=60) were re-evaluated during the study. Those who had no scintigraphy at the time of diagnosis (n=22) or had discordant findings with US (n=6) underwent a new scintigraphy.

RESULTS

Scintigraphies revealed no uptake in 37, ectopia in 35, and hypoplasia in 10 cases. The sensitivity vs specificity for US to detect athyreosis, ectopia, and hypoplasia at the time of initial diagnoses was 90.5 vs 47.8, 10 vs 100, and 100 vs 80.4% respectively. The sensitivity vs specificity for scintigraphy at the time of initial diagnoses was 96.2 vs 100, 92 vs 97.1, and 100 vs 96%, respectively, for each diagnosis. Re-scintigraphy at the time of the study led to a change in the initial diagnosis of 3/6 cases. Repeated US showed disappearance of previously reported hypoplastic thyroid tissues in eight patients.

CONCLUSION

US alone could not differentiate ectopia and athyreosis, whereas scintigraphy alone is also prone to mistakes in newborns and young ages. Dual thyroid imaging is important for precise structural definition of TD.

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.

Congenital hypothyroidism: analysis of discordant US and scintigraphic findings

PURPOSE

To retrospectively review discordant cases of congenital hypothyroidism according to a comparison of findings of ultrasonography (US) and scintigraphy.

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective study with a waiver of informed consent. Data of 300 pediatric patients (mean age, 4.7 weeks; range, 1-48 weeks; male-to-female ratio, 169:131) with congenital hypothyroidism who underwent technetium 99m radioisotope scintigraphy and US were reviewed. Scintigraphic scans were analyzed for location and range of the radioisotope uptake. US images were analyzed for location and thyroid volume. If a normal thyroid was not detected, ectopic thyroid was evaluated. Detection of focal thyroid abnormalities was recorded. Correlation between radioisotope uptake at scintigraphy and volume of normally located glands measured at US was analyzed by using the Pearson correlation test. Differences between results of thyroid function testing and radiologic data among subtypes of congenital hypothyroidism were analyzed with analysis of variance and Scheffe multiple comparison test.

RESULTS

Among 55 patients with no radioisotope uptake, the appearance of the thyroid gland on US scans was normal in 42 patients (76%). This finding was attributed to hypopituitarism (n = 3), maternal antibody-induced hypothyroidism (n = 4), transient elevated thyrotropin (n = 5), and unknown causes (n = 30). Ectopic tissue was not detected at US (sensitivity, 78%; specificity, 100%) in six patients with a diagnosis of ectopy based on scintigraphic findings. Correlation between radioisotope uptake and US thyroid volume was statistically significant (P < .001). Correlation of results from thyroid function testing (thyrotropin, thyroxine, thyroglobulin) and radiologic data (radioisotope uptake, US measurement of volume) with subtypes of congenital hypothyroidism was significant (P < .001). Solid thyroid nodules were present in the thyroid gland in 0.7% (two of 300) of cases.

CONCLUSION

Use of both scintigraphy and US results in a more complete depiction of neonatal congenital hypothyroidism than either test alone.

Congenital hypothyroidism: etiology

The etiology of congenital hypothyroidism (CH) is important in determining its severity, prognosis, genetic counseling and clinical management.

AIMS

investigate the causes of CH and their severity using serum levels of FreeT4 and TSH.

PATIENTS AND METHODS

243 neonates with CH (61% were girls) diagnosed by the Neonatal Screening Program of Minas Gerais between 1996 and 2003. The thyroid function was assessed through serum FreeT4 and TSH by chemilumiscence. CH etiology was evaluated by ultrasonography, scintigraphy, potassium perchlorate discharge test and serum thyroglobulin levels.

RESULTS

Out of 243 patients, dysgenesis was found in 114 (47%): 3.3% had athyreosis; 0.4% eutopic dysgenetic gland due to maternal use of 131I; 22% ectopic glands (8.6% an isolated ectopic gland and 13% also an eutopic dysgenetic thyroid); 9% eutopic dysgenesis, 8.6% hypoplasia and 3.7% hemiagenesis. Thyroid in situ was found in 129 (52%): 23.5% had iodide organification defect; 3.7% thyroglobulin synthesis defect; 6.2% other 0.4% dyshomonogenesis; iodide transport defect; 1.2% transient CH and 18% a normal gland. Patients with dysgenesis had a more severe CH than those with thyroid in situ (TSH 248.08 vs. 18.17 microIU/mL and FT4 0.32 vs. 0.95 ng/dL, p < 0.001).

CONCLUSIONS

Some cases had more complex dysgenesis, presenting ectopia associated to a dysgenetic eutopic gland. The ultrasound was the best tool to detect the dysgenetic tissue, but the scintigraphy was the most effective in identifying the functioning tissue. The thyroid hormone synthesis defects were found more frequently than expected, but in some cases they could not be defined.

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.

Heterogeneous tissue in the thyroid fossa on ultrasound in infants with proven thyroid ectopia on isotope scan--a diagnostic trap

BACKGROUND

Thyroid imaging is of proven help in establishing a diagnosis of congenital hypothyroidism in infants. US often shows tissue in the thyroid fossa when radionuclide scintigraphy reveals only ectopic uptake.

OBJECTIVE

Our hypothesis was that the use of US alone could lead to the mistaken diagnosis of normal or dysplastic thyroid in cases of scintigraphy-proven thyroid ectopia.

MATERIALS AND METHODS

We undertook a detailed retrospective review and analysis of imaging and concurrent biochemistry in infants with thyroid ectopia, confirmed by radionuclide scintigraphy.

RESULTS

Eighteen infants had thyroid ectopia; ten of the original US reports had suggested that cervical thyroid tissue was present. Review showed bilateral tissue in the thyroid fossa in all that was non-thyroidal in nature since, apart from showing no radionuclide uptake, it exhibited some or all of the following typical features: hyperechogenicity, heterogeneity, small size, poor vascularity, and anechoic and/or hypoechoic cysts. Also, extension of the tissue both around and behind the large cervical blood vessels was a universal finding.

CONCLUSION

Considerable experience is required to interpret neonatal thyroid US. We caution against diagnosing a dysplastic/hypoplastic thyroid gland in situ on the basis of US alone, particularly if the tissue exhibits any of the non-thyroidal features described.

Morphogenesis of the thyroid gland

Congenital hypothyroidism is mainly due to structural defects of the thyroid gland, collectively known as thyroid dysgenesis. The two most prevalent forms of this condition are abnormal localization of differentiated thyroid tissue (thyroid ectopia) and total absence of the gland (athyreosis). The clinical picture of thyroid dysgenesis suggests that impaired specification, proliferation and survival of thyroid precursor cells and loss of concerted movement of these cells in a distinct spatiotemporal pattern are major causes of malformation. In normal development the thyroid primordium is first distinguished as a thickening of the anterior foregut endoderm at the base of the prospective tongue. Subsequently, this group of progenitors detaches from the endoderm, moves caudally and ultimately differentiates into hormone-producing units, the thyroid follicles, at a distant location from the site of specification. In higher vertebrates later stages of thyroid morphogenesis are characterized by shape remodeling into a bilobed organ and the integration of a second type of progenitors derived from the caudal-most pharyngeal pouches that will differentiate into C-cells. The present knowledge of thyroid developmental dynamics has emerged from embryonic studies mainly in chicken, mouse and more recently also in zebrafish. This review will highlight the key morphogenetic steps of thyroid organogenesis and pinpoint which crucial regulatory mechanisms are yet to be uncovered. Considering the co-incidence of thyroid dysgenesis and congenital heart malformations the possible interactions between thyroid and cardiovascular development will also be discussed.

Diagnostic spectrum of congenital hypothyroidism in Turkish children

BACKGROUND

Congenital hypothyroidism (CH) is classified as transient or permanent. Transient CH can be treated with short-term thyroxine replacement therapy or followed up without therapy, whereas lifelong thyroxine replacement is needed in permanent CH. Determination of the underlying etiology is essential for determination of follow-up strategy. The purpose of the present study was therefore to assess the role of color Doppler ultrasonography (CDU) in etiologic diagnosis of CH together with radionuclide method and grayscale ultrasonography (GSU).

METHODS

A total of 182 patients (83 female, 99 male) were evaluated. To determine etiologic diagnosis, the patients underwent a free T4 (fT4), thyroid-stimulating hormone (TSH) and urinary iodine level measurement, and thyroid scintigraphy, perchlorate discharge test, CDU, and GSU.

RESULTS

Fifty-four patients had transient and 97 had permanent CH. Isolated hyperthyrotropinemia was diagnosed in 31 patients. Transient CH was due to iodine deficiency in 22 and excess iodine in 13 patients. In 97 patients with permanent CH, ectopia was present in 32 patients and agenesis of the thyroid gland was found in 22 patients, while 43 were diagnosed with dyshormonogenesis. In the ectopia group, GSU failed to detect ectopic tissues in all cases, whereas CDU was successful in determining the presence of ectopic thyroid in 20 cases. The sensitivity of CDU was 80% in determining ectopic tissue.

CONCLUSION

To determine etiologic diagnosis, radionuclide methods and sonographic modalities should be assessed together. The gold standard in the diagnosis of ectopic thyroid tissue is thyroid scintigraphy. CDU may be a major supportive diagnostic tool in the evaluation of ectopic thyroid gland.

Neonatal screening for congenital hypothyroidism in the Federation of Bosnia and Herzegovina: eight years' experience

This report demonstrates the prevalence of primary congenital hypothyroidism (CH) in the Federation of Bosnia and Herzegovina and summarizes the laboratory data. Neonatal thyroid-stimulating hormone (TSH) was measured in whole blood drawn between the 3rd and 5th days of life and spotted on filter paper using the fluorometric assay. Among the 87,061 neonates, 22 had CH, 13 dysgenetic forms, and nine with thyroids in situ. No differences were found between the two types in terms of TSH and total T4 concentrations. However, thyroglobulin was significantly lower in patients with dysgenetic thyroid tissue (p=0.0023). We conclude that the prevalence of CH in the Federation of Bosnia and Herzegovina is 1:3,957 newborns.

Biochemical severity of thyroid ectopia in congenital hypothyroidism demonstrates sexual dimorphism

BACKGROUND

A recent study suggested that sexual dimorphism affects initial thyroid function in congenital hypothyroidism (CH) but differs according to aetiology of CH.

AIMS

To determine if sexual dimorphism was associated with biochemical severity of CH and its aetiology in our large British population.

METHODS

We examined retrospectively the initial thyroid function tests of 140 infants diagnosed with CH from screening. All infants underwent Tc-pertechnetate radionuclide scans at diagnosis to establish the aetiology of CH prior to commencement of treatment. Patients were classified into athyreosis, ectopia and presumed dyshormonogenesis on the basis of thyroid scans. A comparison of males and females were made within the three aetiological groups for gestational age, birth weight, initial dose of levothyroxine (LT4), screening TSH, confirmatory plasma thyroxine (T4), confirmatory plasma TSH and age of TSH suppression.

RESULTS

There was no significant difference between sexes for gestation, birth weight and initial treatment dose in all aetiological subgroups. In thyroid ectopia, screening TSH and confirmatory plasma TSH were significantly higher in females compared with males (P < 0.01), while confirmatory plasma T4 were significantly lower in females (P < 0.05). No difference was detected between males and females in athyreosis and dyshormonogenesis subgroups for screening TSH, confirmatory plasma TSH and total T4.

CONCLUSION

Sexual dimorphism influenced the biochemical severity of thyroid ectopia in congenital hypothyroidism in our British population. However, this effect was not apparent in patients with athyreosis or dyshormonogenesis. Further advances in the molecular genetics of CH are essential to evaluate this phenomenon further.

Combined ultrasound and isotope scanning is more informative in the diagnosis of congenital hypothyroidism than single scanning

BACKGROUND

Thyroid imaging is helpful in confirming the diagnosis of congenital hypothyroidism and in establishing the aetiology. Although isotope scanning is the standard method of imaging, ultrasound assessment may be complementary.

AIM

To determine the strengths and weaknesses of thyroid ultrasound and isotope scanning in neonates with thyroid stimulating hormone (TSH) elevation.

METHODS

Babies from the West of Scotland with raised capillary TSH (>15 mU/l) on neonatal screening between January 1999 and 2004 were recruited. Thyroid dimensions were measured using ultrasonography, and volumes were calculated. Isotope scanning was carried out with a pinhole collimator after an intravenous injection of 99m-technetium pertechnetate.

RESULTS

40 infants (29 female) underwent scanning at a median of 17 days (range 12 days to 15 months). The final diagnosis was athyreosis (n = 11), ectopia (n = 12), hypoplasia (n = 8; 3 cases of hemi-agenesis), dyshormonogenesis (n = 5), transient hypothyroidism (n = 2), transient hyperthyrotropinaemia (n = 1) and uncertain status with gland in situ (n = 1). 6 infants had discordant scans with no isotope uptake but visualisation of thyroid tissue on ultrasound. This was attributed to TSH suppression from thyroxine (n = 3); maternal blocking antibodies (n = 1); cystic degeneration of the thyroid (n = 1); and possible TSH receptor defect (n = 1).

CONCLUSIONS

Isotope scanning was superior to ultrasound in the detection of ectopic tissue. However, ultrasound detected tissue that was not visualised on isotope scanning, and showed abnormalities of thyroid volume and morphology. We would therefore advocate dual scanning in newborns with TSH elevation as each modality provides different information.

Hypothyroïdie congénitale

Congenital hypothyroidism is the principle cause of preventable mental retardation, with a prevalence of 1 in 3,500 neonates. The disorder may be permanent or transitory. Permanent congenital hypothyroidism is caused principally by thyroid dysgenesis. In industrialized countries, mass screening allows the disorder to be diagnosed at birth. The severity is variable but is generally more pronounced in females. The majority of studies point to a genetic origin for the disease and no consistent evidence has been found to suggest a major role for environmental factors. The genetic factors have already been identified and involve several elements (mutations in the TTF-1, TTF-2, PAX8 and TSH receptor genes). The etiological diagnosis is based on scintigraphy, ultrasound and the level of circulating thyroglobulin. At present, treatment is administered at an adapted dose during the first two weeks of life and should allow the child to reach its full intellectual potential. However, minor anomalies have been reported in some treated children, suggesting that this treatment cannot compensate for a certain degree of foetal hypothyroidism.

Update of newborn screening and therapy for congenital hypothyroidism

Unrecognized congenital hypothyroidism leads to mental retardation. Newborn screening and thyroid therapy started within 2 weeks of age can normalize cognitive development. The primary thyroid-stimulating hormone screening has become standard in many parts of the world. However, newborn thyroid screening is not yet universal in some countries. Initial dosage of 10 to 15 microg/kg levothyroxine is recommended. The goals of thyroid hormone therapy should be to maintain frequent evaluations of total thyroxine or free thyroxine in the upper half of the reference range during the first 3 years of life and to normalize the serum thyroid-stimulating hormone concentration to ensure optimal thyroid hormone dosage and compliance. Improvements in screening and therapy have led to improved developmental outcomes in adults with congenital hypothyroidism who are now in their 20s and 30s. Thyroid hormone regimens used today are more aggressive in targeting early correction of thyroid-stimulating hormone than were those used 20 or even 10 years ago. Thus, newborn infants with congenital hypothyroidism today may have an even better intellectual and neurologic prognosis. Efforts are ongoing to establish the optimal therapy that leads to maximum potential for normal development for infants with congenital hypothyroidism. Remaining controversy centers on infants whose abnormality in neonatal thyroid function is transient or mild and on optimal care of very low birth weight or preterm infants. Of note, thyroid-stimulating hormone is not elevated in central hypothyroidism. An algorithm is proposed for diagnosis and management. Physicians must not relinquish their clinical judgment and experience in the face of normal newborn thyroid test results. Hypothyroidism can be acquired after the newborn screening. When clinical symptoms and signs suggest hypothyroidism, regardless of newborn screening results, serum free thyroxine and thyroid-stimulating hormone determinations should be performed.

Diagnostic imaging of the thyroid and adrenal glands in childhood

This article reviews the clinical utility of modern imaging techniques, particularly ultrasound (US), CT, and MRI in children with disorders of the thyroid and adrenal glands. Radionuclide scanning is the modality of choice in making the anatomic diagnosis in neonates with congenital hypothyroidism, while US is most useful in defining nodular thyroid disease. CT and MRI of the thyroid tend to be limited to defining the extent of thyroid carcinoma. Adrenal US is an essential step in the differential diagnosis of ambiguous genitalia or salt-losing crises in the newborn, while CT and MRI are more useful in defining the anatomy of the adrenals in older children with tumors or diffuse hyperplasia of the glands.

Proportion of various types of thyroid disorders among newborns with congenital hypothyroidism and normally located gland: a regional cohort study

OBJECTIVE

To determine the proportion of the various types of thyroid disorders among newborns detected by the neonatal TSH screening programme, with a normally located thyroid gland. Patients and methods Of the 882 575 infants screened in our centre between 1981 and 2002, 85 infants with a normally located gland had persistent elevation of serum TSH values (an incidence of 1/10 383). Six of these 85 patients were lost to follow-up and were therefore excluded from the study. During follow-up, patients were classified as having permanent or transient hypothyroidism.

RESULTS

Among the 79 patients included in the study, transient (n = 30, 38% of cases) and permanent (n = 49, 62% of cases) congenital hypothyroidism (CH) was demonstrated during the follow-up at the age of 0.7 +/- 0.6 years and 2.6 +/- 1.8 years (P < 0.0001), respectively. The proportion of premature births was significantly higher in the group with transient CH (57%) than in the group with permanent CH (2%) (P < 0.0001). A history of iatrogenic iodine overload was identified during the neonatal period in 69% of transient cases. Among permanent CH cases (n = 49), patients were classified as having a goitre (n = 27, 55% of cases), a normal sized and shaped thyroid gland (n = 14, 29% of cases) or a hypoplastic gland (n = 8, 16% of cases). The latter patients demonstrated global thyroid hypoplasia (n = 3), a right hemithyroid (n = 2), hypoplasia of the left lobe (n = 2), or asymmetry in the location of the two lobes (n = 1). Patients with a normal sized and shaped thyroid gland showed a significantly less severe form of hypothyroidism than those with a goitre or a hypoplastic thyroid gland (P < 0.0002). Among permanent CH cases, those with a goitre (n = 27) had an iodine organification defect (n = 10), Pendred syndrome (n = 1), a defect of thyroglobulin synthesis (n = 8), or a defect of sodium iodine symporter (n = 1), and in seven patients no aetiology could be determined. Among permanent cases with a normal sized and shaped thyroid gland (n = 14), a specific aetiology was found in only one patient (pseudohypoparathyroidism) and two patients had Down's syndrome. Among those with a globally hypoplastic gland, a TSH receptor gene mutation was found in two patients.

CONCLUSIONS

A precise description of the phenotype can enhance our understanding of various forms of neonatal hypothyroidism as well as their prevalence and management. It also helps to identify cases of congenital hypothyroidism of unknown aetiology, which will need to be investigated in collaboration with molecular biologists.

Twenty years later: a reevaluation of the contribution of plasma thyroglobulin to the diagnosis of thyroid dysgenesis in infants with congenital hypothyroidism

BACKGROUND

The definition of the type of thyroid dysgenesis in congenital hypothyroidism (CH), ectopy, or athyreosis is important for monitoring patients and for genetic investigations. We have recently encountered infants who in spite of undetectable Technetium uptake on scintigraphy had biochemical results making athyreosis unlikely.

OBJECTIVE

To reevaluate the utility of plasma thyroglobulin (Tg) in this clinical context using new sensitive Tg assays.

SUBJECTS AND METHODS

Plasma Tg was retrospectively determined by two immunoassay systems on specimens obtained at diagnosis in 31 hypothyroid infants with thyroid dysgenesis.

RESULTS

Scintigraphy led to the diagnosis of ectopy in 19 infants and of athyreosis in 12. Seven (58%) of the infants classified as athyreotic by scintigraphy had detectable plasma Tg (>0.2 microg/l), indicating that they had functional thyroid tissue.

CONCLUSIONS

An undetectable plasma Tg should be documented to validate a scintigraphic diagnosis of athyreosis. Conversely, when plasma Tg is undetectable, scintigraphy could be avoided.