Maria Cristina Vigone

A 7-year experience with low blood TSH cutoff levels for neonatal screening reveals an unsuspected frequency of congenital hypothyroidism (CH)

Context  The guidelines of the National Academy of Clinical Biochemistry advocated the use of low bloodspot TSH (b‐TSH) threshold for newborn screening of congenital hypothyroidism (CH). The impact generated by the application of this indication is largely unknown.

Neonatal transient hypothyroidism: aetiological study

AIMS To define the aetiology of neonatal transient hypothyroidism (NTH) and recommend preventive measures. METHODS Maternal and perinatal clinical data on the use of antiseptics, drugs, and contrast agents containing iodine were collected from 40 subjects. Thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroxine (T4), thyroglobulin (TG), TSH receptor antibodies, thyroid peroxidase antibodies and urinary iodine were measured in random neonatal samples. In the mothers with known or suspected thyroid disorders, TSH, FT4, TSH receptor antibodies and thyroid peroxidase antibodies were also measured. RESULTS The NTH aetiology was identified in 85% of cases. More than 50% of the babies with transient hypothyroidism had been exposed to iodine; maternal transfer of antibodies had occurred in a third of them. CONCLUSIONS It is suggested that the practice of using iodine containing disinfectants should be withdrawn, and chlorhexidine substituted instead; that pregnant women should be advised of the adverse effects of using iodine products; and that thyroid function should be monitored whenever iodine is used.

Thyroid nodules and cancer in children and adolescents affected by autoimmune thyroiditis

OBJECTIVE To investigate the association between juvenile autoimmune thyroiditis (JAT) and thyroid cancer in pediatric patients. DESIGN We conducted a retrospective study among children and adolescents affected by JAT. SETTINGS Data from 6 Italian pediatric endocrinology centers were collected. PARTICIPANTS Three hundred sixty-five children and adolescents affected by JAT diagnosed at 3.6 to 17.0 years of age. INTERVENTIONS All patients underwent clinical examination and thyroid function test every 6 to 12 months and thyroid echography every 12 to 24 months. Fine-needle aspiration biopsy was performed in 39 patients with nodule diameter of 1 cm or larger, as well as in 4 patients with nodule diameter of less than 1 cm and echographic findings suspicious for neoplasm. Twenty-three patients underwent surgery. MAIN OUTCOME MEASURES Thyroid function, echographic pattern, nodule diameter, the presence of lymphadenopathy, and cytologic and histologic diagnoses were considered. RESULTS Thyroid nodules were found in 115 patients; findings in 11 of these were consistent with papillary carcinoma, with 5 exhibiting lymph node metastasis. The prevalence of male sex among patients with cancer was greater than that among patients with JAT (odds ratio [OR], 2.95; 95% confidence interval [CI], 1.44-6.20). The growth of nodules during levothyroxine sodium therapy (OR, 15.60; 95% CI, 1.87-181.90) and the finding of lymphadenopathy (OR, 5.44; 95% CI, 1.05-30.50) were statistically significantly associated with the presence of cancer, while uninodularity and hypoechogenicity were not. CONCLUSIONS The observed prevalences of thyroid nodules and thyroid cancer in our JAT case series were 31.5% and 3.0%, respectively. Papillary carcinoma was the only histotype detected. The finding of lymphadenopathy, a lack of response to levothyroxine therapy, and nodule hypoechogenicity suggested malignancy. Fine-needle aspiration biopsy was reliable in selecting patients for referral to surgery.

Congenital hypothyroidism with eutopic thyroid gland: Analysis of clinical and biochemical features at diagnosis and after re-evaluation

CONTEXT In recent years changes in screening strategies for congenital hypothyroidism (CH) led to an increased detection of mild forms of CH, associated with eutopic thyroid gland. OBJECTIVES We aimed to determine the clinical evolution of CH with eutopic thyroid gland and to find out prognostic factors at diagnosis and follow-up. PATIENTS AND METHODS We retrospectively analyzed a group of 84 children with CH and eutopic thyroid gland treated at our institution. They all underwent clinical re-evaluation after the age of 3, based on thyroid function testing after l-thyroxine therapy withdrawal, thyroid ultrasonography, and (123)I scintigraphy with perchlorate discharge test. Genetic analysis was performed in selected cases. RESULTS At re-evaluation, 34.5% of patients showed permanent hypothyroidism and needed l-thyroxine reintroduction, 27.4% had persistent hyperthyrotropinemia (TSH 5-10 mU/L), and 38.1% had transient hypothyroidism. Major risk factors for permanent CH were prematurity, first-degree familial history of goiter/nodules, thyroid hypoplasia at diagnosis, and high l-thyroxine requirements at follow-up. Iodine organification defects were found in 29.7% of patients, 30% of whom harbored DUOX2 mutations. TSH receptor gene mutations were found in 8.7% of patients with persistent thyroid dysfunction and negative perchlorate discharge test. CONCLUSIONS Only one-third of patients with CH and eutopic thyroid gland needed to continue l-thyroxine therapy after re-evaluation. A frequent finding was the persistence of mild hyperthyrotropinemia. The evolution of CH remains difficult to predict, although different clinical features might suggest different outcomes. Mutations in the genes commonly linked to mild forms of CH were documented in a minority of cases.

Comparison of clinical-radiological and molecular findings in hypochondroplasia

Hypochondroplasia is an autosomal dominant skeletal dysplasia characterized by disproportionate short stature. A mutation (N540K) in the fibroblast growth factor receptor 3 (FGFR3) gene was described in some patients with this condition. The aims of the study were to identify the frequency of the FGFR3 gene mutation, to define the salient clinical and radiological abnormalities of the affected subjects, and to verify the contribution of molecular findings to the clinical and radiological definition of hypochondroplasia. Based on the most common radiological criteria, we selected 18 patients with a phenotype compatible with hypochondroplasia. Height, sitting height, and cranial circumference were measured in all patients. Radiographs of the lumbar spine, left leg, pelvis, and left hand were also obtained. The presence of the N540K mutation was verified by restriction enzyme digestions. Half of our patients carried the N540K mutation. Although similar in phenotype to the patients without the mutation, they showed in addition relative macrocephaly. The association of the unchanged/narrow interpedicular distance with the fibula longer than the tibia was more common in patients with gene mutation. Although we did not find a firm correlation between genotype and phenotype, in our study the N540K mutation was most often associated with disproportionate short stature, macrocephaly, and with radiological findings of unchanged/narrow interpedicular distance and fibula longer than tibia.

Congenital Hypothyroidism due to Defects of Thyroid Development and Mild Increase of TSH at Screening: Data From the Italian National Registry of Infants With Congenital Hypothyroidism

CONTEXT Over the years lower TSH cutoffs have been adopted in some screening programs for congenital hypothyroidism (CH) worldwide. This has resulted in a progressive increase in detecting additional mild forms of the disease, essentially with normally located and shaped thyroid. However, the question of whether such additional mild CH cases can benefit from detection by newborn screening and early thyroid hormone treatment is still open. OBJECTIVE The aim of this study was to estimate the frequency of cases with mild increase of TSH at screening in the Italian population of babies with permanent CH and to characterize these babies in terms of diagnosis classification and neonatal features. METHODS Data recorded in the Italian National Registry of infants with CH were analyzed. RESULTS Between 2000 and 2006, 17 of the 25 Italian screening centers adopted a TSH cutoff at screening of <15.0 μU/mL. It was found that 21.6% of babies with permanent CH had TSH at screening of 15.0 μU/mL or less, whereas this percentage was 54% in infants with transient hypothyroidism. Among the babies with permanent CH and mild increase of TSH at screening (≤15 μU/mL), 19.6% had thyroid dysgenesis with serum TSH levels at confirmation of the diagnosis ranging from 9.9 to 708 μU/mL. These babies would have been missed at screening if the cutoff had been higher. CONCLUSIONS Lowering TSH cutoff in our country has enabled us to detect additional cases of permanent CH, a number of which had defects of thyroid development and severe hypothyroidism at confirmation of the diagnosis.

Frequent TSH Receptor Genetic Alterations with Variable Signaling Impairment in a Large Series of Children with Nonautoimmune Isolated Hyperthyrotropinemia

CONTEXT Heterozygous mutations in the TSH receptor gene (TSHR) are associated with partial TSH resistance, characterized by isolated nonautoimmune hyperthyrotropinemia (NAHT). The prevalence and management of this condition is controversial. OBJECTIVE Our objective was to investigate the prevalence and clinical impact of TSHR alterations in a large series of pediatric patients with NAHT and to dissect their mechanism of action. DESIGN AND SETTING For this prospective multicenter study, clinical data and samples were collected in the clinical units and conveyed to a centralized laboratory for analysis. PATIENTS Subjects included 153 unrelated patients with NAHT aged <18 yr. Exclusion criteria included thyroid dysgenesis or major associated congenital defects. MAIN OUTCOME MEASURES Parameters of thyroid function, TSHR gene analysis, and TSHR functional assays were evaluated. RESULTS The frequency of heterozygous nonpolymorphic TSHR variations was 11.8%. We identified seven previously unknown variations: a frameshift (p.Q33PfsX46), one intronic (g.IVS4+2A→G), and five novel missense (p.P162L, p.Y466C, p.I583T, p.I607T, and p.R609Q) variations. The missense variations variably affected TSHR membrane expression and G(s) and/or G(q/11) signaling. Several variations cosegregated with NAHT in the affected families. Parameters of thyroid function were similar between affected and unaffected family members. CONCLUSIONS Nonpolymorphic alterations in the TSHR gene are commonly associated with isolated NAHT in young patients, thus configuring partial TSH resistance as the most frequent inheritable cause of isolated NAHT. The identification of TSHR defects may thus be helpful for a tailored management of subclinical hypothyroidism. We provide further evidence that besides the well-known defects in G(s) signaling, TSHR genetic alternations found in NAHT may frequently impair the G(q/11) pathway.

Frequency of Hashimoto's thyroiditis antecedents in the history of children and adolescents with graves' disease.

Background: The development of Graves’ disease (GD) from Hashimoto’s thyroiditis (HT) has sporadically been reported, but no data are available concerning the prevalence of this sequence of events in GD patients. Our aim was to ascertain HT antecedents in the history of GD children in order to assess for the first time the relative frequency of the event sequence leading from HT to GD in a pediatric population. Study Population and Results: In 105/109 patients, no HT antecedents were documented at GD presentation. The remaining 4 patients had previously exhibited a picture of HT with either hypothyroidism or euthyroidism. The interval between HT diagnosis and GD presentation ranged from 1.5 to 2.8 years. Serum thyrotropin receptor antibodies were higher in the patients with no HT antecedents. Conclusions: In at least 3.7% of the children with GD, hyperthyroidism may be preceded by HT presentation with either hypothyroidism or euthyroidism. The clinical course of GD in these patients is not different from the one observed in those with no HT antecedents. Our report confirms the existence of a continuum between HT and GD within the spectrum of autoimmune thyroid diseases.

The Clinical and Molecular Characterization of Patients With Dyshormonogenic Congenital Hypothyroidism Reveals Specific Diagnostic Clues for DUOX2 Defects

CONTEXT Mutations in the DUOX2 gene have been associated with transient or permanent congenital hypothyroidism due to a dyshormonogenic defect. OBJECTIVE This study aimed to verify the prevalence of DUOX2 mutations and the associated clinical features in children selected by criteria supporting a partial iodide organification defect (PIOD). PATIENTS AND METHODS Thirty children with PIOD-like criteria were enrolled and genotyped. A detailed clinical characterization was undertaken together with the functional analysis of the DUOX2 variations and the revision of the clinical and molecular data of the literature. RESULTS In this large selected series, the prevalence of the DUOX2 mutations was high (37%). We identified 12 missense variants, one splice site, and three frameshift DUOX2 mutations. Functional analyses showed significant impairment of H2O2 generation with five missense variants. Stop-codon mutants were shown to totally abolish DUOX2 activity by nonsense-mediated RNA decay, exon skipping, or protein truncation. DUOX2 mutations, either mono- or biallelic, were most frequently associated with permanent congenital hypothyroidism. Moreover, the present data suggested that, together with goiter and PIOD, the most significant features to select patients for the DUOX2 analysis are the low free T4 and the high TSH concentrations at the first postnatal serum sampling, despite borderline blood spot TSH. Interestingly, the analysis of previously described DUOX2 mutated cases confirmed the validity of these findings. CONCLUSIONS The defects in the peroxide generation system are common among congenital hypothyroidism patients with PIOD. The most robust clinical parameters for selecting patients for DUOX2 analysis have been identified, and several DUOX2 variants have been functionally characterized.

Thyroid abnormalities in children and adolescents with mccune-albright syndrome

Background: To date, there is no agreement about the frequency or the features of thyroid abnormalities in McCune-Albright syndrome (MAS). The aim of our study was to detect thyroid abnormalities in a cohort of MAS children and adolescents and to give indications for their treatment and follow-up. Methods: In 36 patients, 22 females and 14 males, thyroid function and sonographic features of thyroid were evaluated every 6–12 months. Results: Three males and 1 female had hyperthyroidism: 2 with nodular, 2 with diffuse goiters. They were treated with methimazole (0.2–0.5 mg/kg/day) with good clinical and biochemical responses. The remaining 32 patients were euthyroid, even if 7 displayed sonographic alterations, of whom 5 had nodular goiter with nodules >1 cm, and 2 micronodular goiter. Fine-needle aspiration biopsy was performed in 2 patients with nodules >1 cm, 1 showing hemorrhagic nodule and 1 colloid cystic nodule. Conclusions: Prevalence of thyroid alterations in the studied MAS series was 31%. 64% of 11 patients with thyroid alterations had nodular goiters, with nodules >1 cm. As the onset of thyroid disease ranged from 1 to 20 years, a strict monitoring of thyroid function is recommended every 6 months. Satisfactory treatment can be obtained and maintained with antithyroid drugs.