Prevalence and course of thyroid dysfunction in neonates at high risk of Graves' disease or with non-autoimmune hyperthyroidism

OBJECTIVE

Neonatal hyperthyroidism may be caused by a permanent non-autoimmune genetic disorder or, more frequently, by maternally transmitted high serum TRAb levels. Variable thyroid dysfunction may be observed in this second context. We aimed to evaluate the prevalence of neonatal non-autoimmune hyperthyroidism and of the different types of thyroid function in neonates with a high risk of hyperthyroidism due to maternal Graves' disease (GD).

DESIGN AND METHODS

This observational cohort study included all neonates identified in the database of a single academic pediatric care center, over a period of 13 years, as having non-autoimmune hyperthyroidism or an autoimmune disorder with high TRAb levels (above 6 IU/L) transmitted by their mothers. Patients were classified as having neonatal hyperthyroidism, hypothyroidism, or euthyroidism with a permanent or transient disorder.

RESULTS

Two of the 34 consecutive neonates selected (6%) had permanent non-autoimmune hyperthyroidism due to germline (n = 1) or somatic (n = 1) mutations of the TSH receptor gene. The patients with high serum TRAb levels at birth had transient hyperthyroidism (n = 23), hypothyroidism (primary n = 2, central n = 3) or persistent euthyroidism (n = 4).

CONCLUSION

These original findings highlight the need for careful and appropriate monitoring of thyroid function in the long term, not only for the rare patients with non-autoimmune neonatal hyperthyroidism, but also for repeat monitoring during the first month of life in neonates with maternally transmitted high TRAb levels, to ensure the early identification of thyrotoxicosis in more than two thirds of cases and to detect primary or central hypothyroidism, thereby potentially decreasing associated morbidity.

Association Between Neonatal Thyroid Stimulating Hormone Status and Maternal Urinary Iodine Status

BACKGROUND

Maternal urinary iodine concentration (MUIC) and percentage of neonates with Thyroid stimulating hormone (TSH) >5 mIU/L are amongst the parameters suggested for assessing adequate iodine status.

OBJECTIVE

To assess the correlation between MUIC and neonatal TSH levels.

STUDY DESIGN

Cross-sectional.

SETTINGS

Tertiary care center in Delhi, India, between November 2015 to November 2016.

PARTICIPANTS

Postnatal mother-neonate dyads.

METHODS

TSH levels assessed among neonatal samples were stratified as below and above 5 mIU/L. MUIC was measured in 544 mothers, 400 mother-neonate dyads with neonatal TSH levels >5 mIU/L (cases) and 144 mother-neonate newborn mother dyads with neonatal TSH <5 mIU/L (controls).

RESULTS

Results: The percentage of mothers with iodine insufficiency (9.8% vs 5.6%) as well as iodine excess (54.3% vs 41.7%) were significant higher in cases than controls. Mean TSH was also higher (P=0.0002) in both the iodine deficient and iodine excess group. There was no correlation between neonatal TSH values and MUIC.

CONCLUSION

Lack of correlation between neonatal TSH and MUIC is due to iodine excess together with iodine deficiency.

Screening for thyroid disease in pregnancy: a review

Screening for thyroid disease in pregnancy remains a contentious issue. This review presents these diverging views and discusses their reasons as well as the relevant facts. The final aim is to establish the information gaps and limitations - technological or otherwise - which still need to be eliminated in order to settle the debate conclusively. The prevalence of the more common thyroid dysfunctions that occur in and after pregnancy is discussed. The subsequent impact of these disorders on mother and offspring is also described. Special focus is placed on the benefits and setbacks of currently available and newly proposed investigations, which assay serum hormone levels, serum autoantibody levels, and/or use clinical data. It is pointed out that the relevance of screening varies from one region of the world to the other, based on the content of iodine and selenium in food and water. The review then discusses the current major arguments for and against screening, as well as recommendations and proposed alternatives.

Neonatal hyperthyrotropinemia is associated with low birth weight: a twin study

OBJECTIVE

Contradictory reports ascribe neonatal hyperthyrotropinemia (HT) to prematurity or small weight for gestational age. We aimed to evaluate the association between neonatal HT and birth weight (BW), recovery rate of the disorder, and possible association with perinatal stress.

DESIGN

Based on a neonatal screening database, a retrospective twin study was designed where within-pair differences in thyroid function were evaluated while controlling for differences in gestational age and thyroid-affecting environmental confounders.

METHODS

Two thousand five hundred and ninety-five twin pairs that were screened both for TSH and thyroxine (T(4)) over 3 years were included. TSH and T(4) levels were evaluated along with BW, birth order, gender, and 17-hydroxyprogesterone (17OHP) that was considered as a surrogate marker for stress.

RESULTS

Of all the twin pairs, 7.2% had neonatal HT. Among 156 pairs, HT was more prevalent in the smaller twins (64%; P<0.001), especially in the discordant pairs (76%; P=0.001). Seventy-five percent of the twins demonstrated a recovery within the first few weeks of life. 17OHP levels were similarly distributed between twins with and without HT. In a cohort of 1534 twin pairs with normal thyroid function, mean TSH levels were significantly higher in the smaller than in the larger twin in the whole group (4.1±3.2 vs 3.8±2.9 mIU/l; P<0.001) and especially among discordant twins (4.7±3.4 vs 3.8±3.0 mIU/l; P<0.001).

CONCLUSIONS

Elevated TSH levels are associated with low BW, both in infants with HT and in normal neonates. A rapid recovery rate is expected in most cases.

Pyramidal lobe of the human thyroid gland: an anatomical study with clinical implications

The presence, position, extent, relationships to neighboring structures and size of the human pyramidal lobe were investigated in 58 human post-mortem specimens in order to determine the variability of this structure. The pyramidal lobe is found in 55.2% of cases as a single conical extension of the thyroid gland. It was present more often in male (53.1%) than in female (46.9%) specimens and located slightly more often on the left side of the midsagittal plane (53.1%). According to the origin and location of its base, we defined five types of pyramidal lobe, with the left-sided types (Types III and IV) being predominant. The pyramidal lobe was 22.6 mm long, 11.2 mm wide and 3.6 mm thick (mean values). The means of all measured parameters were higher in female than in male specimens (pyramidal lobe was 2.3 mm longer, 1.6 mm wider and 0.4 mm thicker in female specimens) but these differences were not significant. In addition, we found that the size of the pyramidal lobe was dependent on the presence of a fibrous or muscular band that may represent a fibrous remnant of the thyroglossal duct or the levator glandulae thyroideae muscle. The pyramidal lobe was four times longer and its base was two and a half times wider and three times thicker when it was associated with this band. We believe that our data can be used to perform safer and more effective partial thyroidectomy in order to preserve thyroid function after surgical treatment.

Serum thyroid function tests in neonates of mothers with thyroid disease

Maternal thyroid disease can affect the newborn baby leading to neonatal hyperthyroidism or hypothyroidism. Babies born to mothers with thyroid disease get thyroid function tests (TFT) done randomly irrespective of the nature of maternal thyroid disease and medication .The aim of this study was to determine which babies are at-risk and need thyroid function monitoring besides a simple Newborn screening test and to produce a local guideline for management of this particular cohort of babies. This prospective study done on 30 newborn babies concluded that routine newborn screening test is enough to monitor majority of these babies. A new local guideline is formulated accordingly.

Autoimmune Thyroid Disease and Pregnancy: Relevance for the Child

As a group, the autoimmune thyroid diseases, including Graves' disease, Hashimoto's thyroiditis, and primary myxedema, are among the most common endocrine disorders encountered during pregnancy. Therefore, a substantial number of offspring will grow and develop in utero under conditions of maternal autoimmune thyroid disease and may be exposed to abnormal maternal thyroid function, maternal thyroid antibodies, and/or numerous therapeutic agents used to manage maternal thyroid dysfunction. This article reviews the effects that these various aspects of maternal autoimmune thyroid disorders can have on pregnancy outcome, as well as on the physical growth, neuropsychological development, and thyroid status of the developing fetus and neonate.

Modified approach for lingual thyroid transposition: report of two cases

Lingual thyroid is a rare congenital anomaly of thyroid development resulting from failure of the thyroglossal duct to migrate from the foramen cecum to the prelaryngeal site. The lingual thyroid associated with a fetal adenoma is even more unusual. We presented two cases of lingual thyroid, one associated with fetal adenoma. The ectopic gland was transposed into the muscle space at the floor of the mouth using an extraoral midline lower lip, mandible and tongue-splitting approach in case 1, and a transoral lower lip degloving and midline mandibulotomy and tongue-splitting approach in case 2. Sixteen-year follow-up of case 1 and 6-month follow-up of case 2 showed that the transposed thyroids achieved normal function. Case 2 had no visible scar in the lower lip and mental area. Surgical transposition of the lingual thyroid to the floor of the mouth with the vascular supply intact offers a promising approach for the treatment of this anomaly. The transoral lower lip degloving and midline-splitting approach is recommended because of its better cosmetic outcome.

Management of neonatal endocrinopathies--best practice guidelines

Neonatal emergencies are uncommon, but may lead to significant morbidity and mortality if not recognised and managed promptly. Disorders of sex development, hypoglycaemia, thyrotoxicosis and calcium balance are discussed, with emphasis on the clinical assessment, investigations and management of these disorders in the acute setting.

[Effects of maternal hyperthyroidism and antithyroid drug therapy on thyroid function of newborn infants]

OBJECTIVE

To evaluate the relationship between the incidence of abnormal thyroid function of newborns and maternal hyperthyroidism with antithyroid drug therapy.

METHOD

The clinical data of 35 neonates born to mothers with hyperthyroidism from 1983 to 2003 in Peking Union Medical College Hospital were retrospectively analyzed. According to the maternal thyroid function and the antithyroid drugs taken during pregnancy, subjects were divided into different groups.

RESULTS

The proportion of abnormal thyroid function in newborn was 48.6% (17/35). The prevalences of primary hypothyroidism, subclinical hypothyroidism, hypothyroxinemia, and central hypothyroidism were 29.4%, 29.4%, 35.3%, and 5.9%, respectively. The incidence of abnormal thyroid function of neonates whose mothers did not take the antithyroid drugs (ATDs) until the third trimester of pregnancy was significantly higher than those without and with ATDs during the first or second trimester (P < 0.01). The incidence of abnormal thyroid function significantly increased in premature neonates, neonates whose mothers with modest or heavy pregnant hypertension, or neonates whose core serum thyroid-stimulating hormone or serum anti-thyroid peroxidase antibodies levels were abnormal.

CONCLUSION

The risk of abnormal thyroid function of infants whose hyperthyroid mothers did not take ATDs until the third trimester of pregnancy may be increased. Prompt diagnosis and appropriate treatment of hyperthyroidism in pregnant women are essential for the prevention of neonatal thyroid functional abnormality.

Non-iatrogenic pathology of the preterm infant

Non-iatrogenic anatomical findings at autopsy provide insight into preterm infant physiology. The different patterns of lipid accumulation in the adrenal may correspond to long-term differences in stress response. Cardiac papillary muscle infarction occurs with asphyxia or shock and can explain myocardial dysfunction. Underdevelopment of preterm kidneys may correlate with susceptibility to renal disease and hypertension in adult life. Immaturity of the lung or immature responses to inflammation, rather than high oxygen concentrations or high ventilation pressures, may underlie chronic lung disease in premature infants. Hepatic extramedullary haematopoiesis is normal but, if excessive or abnormally persistent, can be an indicator of fetal disease. Hypertrophic somatostatin islet cells found with intra-uterine growth retardation may correlate with low serum insulin. Thymic involution may mark the degree of stress. Small thyroglobulin stores may limit the premature neonate's initiation of thermogenesis.

Endoscopic fibrin sealing of congenital pyriform sinus fistula

Pyriform sinus fistula is a very rare branchial apparatus malformation, often appearing in the form of a cervical inflammatory process (abscess or suppurative thyroiditis), especially in infants. Failure to diagnose this lesion may result in unexpected recurrence. A case of recurrent suppurative thyroiditis caused by pyriform sinus fistula in a 9-year-old girl is reported. In the latency period of infection, the fistula tract was identified by a barium meal contrast study. Direct endoscopy showed the fistula internal orifice at the apex of the left pyriform fossa. The fistula was completely obliterated by injection of fibrin glue. Suppurative thyroiditis is reported mainly in the pediatric literature, and the reported case is the first to be managed endoscopically by injection of fibrin adhesive.

[Current approaches to estimating the sizes of the thyroid in neonates and infants from ultrasonographic data]

The thyroid was ultrasonographically studied in 384 pre-term babies aged 4-8 days of life. The sizes of thyroid lobes were determined; the echogenicity of the thyroid was compared with that of the parotid salivary gland. The infants were born by apparently healthy mothers and females with iodine deficiency. An original procedure for neonatal ultrasound study was developed. Data statistical processing yielded a formula of the individual standard of a thyroid volume, which allows neonatal goiter and thyroid hypoplasia to be established at early stages of life.

Thyroid dysgenesis caused by PAX8 mutation: the hypermutability with CpG dinucleotides at codon 31

We identified a novel mutation (CGC to T GC) at codon 31 of the Paired box 8 gene, an important transcription factor in the development of the thyroid gland. Mutations at this codon have been independently reported in 2 cases (CGC to CA C). These transitions are considered typical CpG-consequence mutations and account for hypermutability at this position.

Autosomal dominant transmission of congenital thyroid hypoplasia due to loss-of-function mutation of PAX8

Congenital hypothyroidism (CH) is a relatively frequent and potentially severe disease. It is classically subdivided into: 1) thyroid dysgenesis (TD), a defect in the organogenesis of the gland leading to hypoplastic, ectopic, or absent thyroid gland; or 2) thyroid dyshormonogenesis, a defect in one of the biochemical mechanisms responsible for thyroid hormone synthesis. Most cases of TD are sporadic, although familial occurrences have occasionally been described. Recently, several genes have been implicated in a small proportion of TD, but, in the majority of the cases, the etiology remains unknown. PAX8 is a transcription factor involved in thyroid development. So far, three loss-of-function mutations of PAX8 have been described, two in sporadic cases and one in familial thyroid hypoplasia. Here, we describe a novel mutation of PAX8 causing autosomal dominant transmission of CH with thyroid hypoplasia. The mutation consists of the substitution of a tyrosine for cysteine 57 in the paired domain of PAX8. When tested in cotransfection experiments with a thyroid peroxidasse promoter construct, the mutant allele was unable to exert its normal transactivation effect on transcription. Our results give further evidence that, contrary to the situation in knockout mice, haplo-insufficiency of PAX8 is a cause of CH in humans.

The effect of abnormal intrauterine thyroid hormone economies on infant cognitive abilities

OBJECTIVE

To evaluate how intrauterine and neonatal thyroid hormone deficiencies affect infant cognitive abilities.

METHOD

26 infants with intrauterine or neonatal thyroid hormone deficiency and 20 full-term infants with normal thyroid economies were studied at 6 months of age or corrected age. Reasons for thyroid hormone deficiency were maternal hypothyroidism, maternal hyperthyroidism treated with antithyroid medication, congenital hypothyroidism, and low-risk prematurity. A computer-generated task during which infants' eye-movements were videotaped was used to assess attention, memory, and learning abilities

RESULTS

Data from transcribed videotapes showed the study group was significantly less attentive and had longer reaction times than controls but did not differ on indices of sustaining attention or learning. Within thyroid-deficient groups, offspring of treated hyperthyroid mothers showed an atypical profile suggestive of hypervigilance.

CONCLUSION

A decreased fetal or maternal thyroid hormone supply in pregnancy is associated with infants' poorer attention and altered rates of information processing.

Sequence analysis of thyroid transcription factor-1 gene reveals absence of mutations in patients with thyroid dysgenesis but presence of polymorphisms in the 5' flanking region and intron

Congenital hypothyroidism is caused by several mechanisms. The most common cause worldwide is iodine deficiency, but in iodine-sufficient regions thyroid dysgenesis is the most common cause of congenital hypothyroidism. In the present study we analyzed the thyroid transcription factor-1 (TTF-1) gene in patients with congenital hypothyroidism due to thyroid dysgenesis: three patients with athyrosis, five with ectopy, and one with hypoplasia. Genomic DNA was isolated from peripheral leukocytes, and the TTF-1 gene, including a 5' flanking region, two exons and one intron was amplified by polymerase chain reaction (PCR) with 4 pairs of primers. The PCR products were directly sequenced by the Dye Terminator Cycle Sequencing method. We could not find any mutations specific for the thyroid dysgenesis in the 5' flanking region, two exons and one intron in the TTF-1 gene, but two heterozygous nucleotide substitutions were detected in the intron: a G to A transition at nucleotide 469 (G469A) and a C to A transversion at nucleotide 866 (C866A). The same nucleotide changes were detected in some normal subjects. Allelic frequencies of the polymorphisms G469A and C866A were 23% and 10%, respectively. Another normal polymorphism in the 5' flanking region was a G to T transversion at nucleotide -845 from the transcription start site (G-845T). The allelic frequency of the polymorphism G-845T was 28%. We also found 12 polymorphisms in the 5' flanking region, two in the intron and one in the 3' untranslated region. These polymorphisms were detected in 100% chromosomes. These results suggest that congenital hypothyroidism associated with thyroid dysgenesis is unlikely to be caused by mutations in the TTF-1 gene in which, however, were detected normal polymorphisms in the 5' flanking region, intron and 3' untranslated region.

The role of ultrasound and oesophagography in the management of acute suppurative thyroiditis in children associated with congenital pyriform fossa sinus

The thyroid is remarkably resistant to infection. Hence, when an infection does occur, the presence of a pyriform fossa sinus must be considered, particularly if it is recurrent and left sided. The aim of this paper is to alert radiologists to the existence, clinical presentation, and ultrasonographic and oesophagographic appearances of a pyriform fossa sinus. We present the role of ultrasound and oesophagography in five children with pyriform fossa sinus associated with suppurative thyroiditis. In four children the abnormality was on the left and on the right in one.

[Diagnosis and therapy of fetal thyroid gland dysfunction in primary maternal disease]

Fetal and maternal thyroid function are working independently under physiologic conditions. In case of maternal autoimmune hyperthyroidism during pregnancy there is an up to 12% chance for the fetus to develop thyroid dysfunction, mediated by the transplacental passage of maternal immunoglobulins directed against TSH receptors in the fetal thyroid gland. This may lead to intrauterine growth retardation, craniosynostosis, preterm delivery, perinatal death, etc. Sonography and fetal blood sampling provide important information to detect fetuses at risk and allow intrauterine therapy. Furthermore prenatal diagnosis is important in case of maternal antithyroid drug ingestion possibly leading to fetal hypothyroidism and goitre. The cooperation of specialists for internal and fetal medicine is required for the management of maternal thyroid disease in pregnancy.

[Histofunctional state of the thyroid gland in pregnancy and in progeny under experimental regime of iodine intake]

The paper is devoted to the study of the character of structural changes in the thyroid gland in pregnancy and in progeny of rats with deficient or excessive intake of iodine. A stable model of thyroid transformation was developed under the conditions of the changed regimen of iodine intake in pregnancy. Predominantly proliferative changes of the epithelial component in the thyroid tissue developed in pregnancy both with deficient and excessive iodine. Based on the histochemical, morphometric, histostereometric analysis a close relationship between the character of transformation of maternal thyroid and the progeny thyroid tissue was found. Dynamics of the development of postnatal thyroid tissue in the presence of congenital structural-functional disorders is described.

Mutations in the gene encoding thyroid transcription factor-1 (TTF-1) are not a frequent cause of congenital hypothyroidism (CH) with thyroid dysgenesis

Permanent congenital hypothyroidism (CH) has an incidence of 1/3000-4000 newborns and is among the most frequent cause of mental retardation and neurological alterations in children. In 80% to 85% of cases CH is associated with thyroid dysgenesis. A group of 61 patients with CH (22 with agenesis, 18 with ectopy, 1 with hypoplasia, and 20 cases with CH without thyroid enlargement but not further characterized) and 30 normal subjects were examined for the presence of mutations in the gene encoding the thyroid transcription factor 1 (TTF-1). The coding-region of the TTF-1 gene was analyzed in all cases by the single stranded conformational polymorphism (SSCP) and no mutations were detected. Direct sequencing also carried out in patients with thyroid agenesis confirmed the absence of mutations or polymorphisms in the TTF-1 gene. The absence of mutations in the TTF-1 gene in our samples indicates that the mutations in the TTF-1 gene are not a frequent cause of CH.

Absence of mutations in the gene encoding thyroid transcription factor-1 (TTF-1) in patients with thyroid dysgenesis

Thyroid transription factor-1 (TTF-1) is a homeodomain-containing nuclear transcription factor, important in regulation of the thyroid-specific genes thyroglobulin (Tg), thyroperoxidase (TPO), and thyrotropin receptor (TSHR). TTF-1 is an early biochemical marker of thyroid differentiation, essential for thyroid development and maintenance of the thyroid differentiated state. It is possible that mutations in titf1 gene encoding TTF-1 could result in failure of the thyroid gland to develop. Single strand conformation polymorphism (SSCP) was used to detect the presence of titf1 gene mutation in a group of 15 patients with congenital hypothyroidism. The etiology of the congenital hypothyroidism included thyroid agenesis (9), sublingual ectopic thyroid (4), and severe hypoplasia (2). The analysis did not identify any titf1 gene mutation, among these patients. These results rule out the presence of titf1 mutations, at least in the coding region, in our thyroid dysgenesis patients. Mutations in titf1 coding region may be an extremely rare event, and was not detected in our small sample size or, alternatively, such a mutant might even be viable since TTF-1 plays an important role in lung, brain, and pituitary development.

Thyroid hemiagenesis with subacute thyroiditis

A 58-year-old woman with thyroid hemiagenesis associated with subacute thyroiditis is described. Physical examinations revealed a firm nodule with spontaneous pain and tenderness in the left thyroid lobe. A serum thyroid hormone levels were elevated and thyroid scintiscan with 99mTc pertechnetate showed an extremely low uptake, we made a diagnosis of subacute thyroiditis. A 201Tl thyroid scan demonstrated an enlarged left lobe and absence of the right lobe. Ultrasonography of the thyroid gland revealed an enlarged left lobe occupied mostly with a hypoechoic region. An incidental finding was absence of the right lobe. Two months later thyroid function returned to normal. A follow-up thyroid scintiscan revealed a normal left lobe but absent right lobe. The diagnosis of hemiagenesis was confirmed by CT scan. This appears to be the first case report of thyroid hemiagenesis associated with subacute thyroiditis.

Review of antithyroid drug use during pregnancy and report of a case of aplasia cutis

Thioamide therapy has improved the outcome of pregnancies complicated by maternal hyperthyroidism, without long-term effects on cognitive and somatic development. However, there remain questions concerning whether these drugs, especially methimazole (MMI), may be associated with aplasia cutis congenita (ACC) and how best to avoid impairment of fetal thyroid function during their use. We report an example of ACC and review the relevant literature. We conclude that there is insufficient evidence either to establish or eliminate a direct causal relationship between ACC and MMI use. Since propylthiouracil is an equally effective antithyroid agent and has not been associated with ACC, it is the preferred thioamide for hyperthyroidism during pregnancy. Our review also indicates that impairment of neonatal thyroid function may be minimized by using a thioamide dose that is just sufficient to maintain the maternal serum free thyroxine concentration in the high normal or slightly thyrotoxic range.

[The role of ultrasonography in thyroid disease]

Ultrasound examination of the thyroid gland is widely used in the diagnosis of thyroid disease. This test is easy and rapid to perform, widely available and the results are readily interpreted. Using ultrasound the image of foci of disease within the gland are easily identified, especially using high frequency probes which enable solid nodules up to approx 3 mm to be revealed with 10 MHz probes. In non-nodular thyroid disease the ultrasonic structure guides the diagnosis (thyroiditis, Graves' disease). During the follow-up of thyroidectomised patients ultrasound can easily reveal postoperative anatomic variations and an early diagnosis can be obtained of any signs of local recurrence of the primary disease. Only hemiagenesia and hypoplasia can be accurately evaluated in congenital disease, whereas in the event of the persistence of the thyroglossal duct the latter can only be diagnosed if it presents a cystic evolution. Thyroid ectopia cannot be identified and must be studied using thyroscintigraphy, preferably performed using 131I as the isotope. The acquired pathology is classified into phlogistic processes, diffuse or nodular hyperplasia, benign and malignant neoplasia. This classification is widely accepted by virtually all authors. In thyroiditis, ultrasound may facilitate the diagnosis of De Quervain's non-suppurative sub-acute thyroiditis (TANS) and Hashimoto's chronic thyroiditis, although always in association with clinical and laboratory tests. The most frequent thyroid pathology is without doubt goitre. This disorder may occur in a non-nodular (widespread goitre with an endemic or sporadic pattern) or nodular form which may be single or multiple. The term goitre is used to indicate the increased volume of the thyroid gland independently of the causes which have provoked it. Common goitre is defined as being endemic when in some geographic area 10% of the general population or 20% of the school-aged population suffers from thyroid hyperplasia (areas of goitrogenic endemic disease). Graves' disease may be included in the group of thyroid hyperplasia diseases, although it is distinguished from the simple versions by the marked glandular hyperactivity which creates manifest hyperthyroidism. In this pathology ultrasonography must be supplemented by colour-Doppler wherever possible. Thyroid nodules are subdivided in terms of their echostructure into 5 types: liquid, mixed (prevalently solid or prevalently liquid), hyperechogenic solid, isoechogenic solid and hypoechogenic solid. The characteristics of benign nodules are: hypoechogenic structure, regular edges, complete and uniform hypoechogenic peripheral halo.(ABSTRACT TRUNCATED AT 400 WORDS)

Has percutaneous umbilical blood sampling improved the outcome of high-risk pregnancies?

PUBS offers distinct advantages to the perinatologist in the management of the high-risk pregnancy. Improvement in outcome has clearly been attained in the severely anemic fetus, for example, whereas fetal blood sampling has also led to great advances in both diagnosis and treatment of many other perinatal abnormalities. The exact role for PUBS in the management of problems such as intrauterine growth retardation and the fetus at risk for thrombocytopenia in ITP remains controversial. It is quite evident, however, that overall PUBS offers tremendous aid to the perinatologist in management of the high-risk pregnancy, with future promise for even greater application.

Spectrum of serum thyroglobulin elevation in congenital thyroid disorders

Serum thyroglobulin (Tg) data are presented for 47 infants with congenital thyroid disorders. Abnormal elevation of serum Tg (> 250 micrograms/L) occurred in 17% of the population studied, whereas values in excess of 1,000 micrograms/L were demonstrated in 11% of infants. The latter group includes the first report of supraphysiologic Tg elevation in an infant with thyroid gland ectopia, and the highest reported thyroglobulin level in the syndrome of generalized thyroid hormone resistance in an infant homozygous for a novel deletion in the c-erbA beta receptor. Mechanisms involved in the pathogenesis of Tg elevation are discussed. We conclude that Tg elevation in congenital thyroid disorders is more common than previously recognized, and values > 1,000 micrograms/L identify infants with a spectrum of anatomic and biochemical abnormalities.

Risk factors for developmental disorders in infants born to women with Graves disease

OBJECTIVE

To identify risk factors for disorders of fetal growth and thyroid function in the presence of maternal Graves disease.

METHODS

Two hundred thirty pregnancies in gravidas with Graves disease were analyzed. Maternal thyroid status was evaluated by serum free thyroxine (T4) or free T4 index, TSH, and TSH-receptor antibody; personal history of thyrotoxicosis and total dose of antithyroid drugs during pregnancy were also noted. Neonatal thyroid function was assessed at birth and on the fifth day after birth.

RESULTS

Fifteen neonates (6.5%) were small for gestational age (SGA), and this occurrence was significantly associated with thyrotoxicosis lasting for 30 weeks or more of pregnancy, TSH-receptor antibody level of 30% or more at delivery, history of Graves disease of 10 years or longer, and onset of Graves disease before 20 years of age. However, no significant correlation was found between maternal thyroid hormone level and SGA neonates. Thyroid dysfunction developed in 38 infants (16.5%), of whom only four were SGA; development of this dysfunction was significantly related to the mother's total dose of antithyroid drugs, duration of thyrotoxicosis in pregnancy, and/or TSH-receptor antibody level at delivery.

CONCLUSIONS

Duration of maternal Graves disease or thyrotoxicosis, either mild chemical or overt, in pregnancy is significantly associated with SGA neonates. Neonatal thyroid dysfunction is associated with the maternal thyroid condition, especially the serum TSH-receptor antibody level.

Acute suppurative thyroiditis with bilateral piriform sinus fistulae

Although there are many possible routes of infection in AST, the clinician must be aware of a possible fistula between the piriform sinus and the perithyroidal space--especially in patients with recurrent episodes of AST. Diagnosis of this congenital tract requires a high index of suspicion and radiographic demonstration by a barium swallow or endoscopic visualization. Effective treatment of AST with intravenous antibiotics and appropriate surgical intervention have greatly reduced the mortality and secondary complications. Complete fistulectomy, however, is required for permanent cure.

Congenital pyriform sinus fistula: a cause of acute left-sided suppurative thyroiditis and neck abscess in children

Acute bacterial thyroiditis or neck abscesses in children can be caused by infection through pyriform sinus fistulae which usually originate from the tip of the left pyriform sinus. They are thought to be remnants of either the third or fourth pharyngeal pouches. CT, ultrasound and gastrointestinal contrast studies are all useful in clarifying the pathological process and showing the extent.

Lingual thyroid in two natural brothers

Tc99m scanning because of hypothyroidism revealed a lingual thyroid in two natural brothers who had no family history of thyroid disease. No thyroid tissue was found in the neck. Further development under substitution therapy with levothyroxine was normal. The diagnosis of this rare disease in two natural brothers suggests that lingual thyroid may be inherited.

[Children of hyper- and hypothyroid mothers]

A multicenter study was able to utilize 120 medical files of children born from mothers who presented an abnormal thyroid function, 67 euthyroid goiters, 29 hyperthyroidisms, and 24 hypothyroidisms. In the first case, whether or not an inhibiting treatment was initiated, all children were perfectly normal. In case of maternal hyperthyroidism, the risk of malformations is not increased, deaths in utero and mostly in utero growth delays (1 case in 2) are more frequent. At birth, the child may present a hyperthyroidism due to the effect of SAT with elevated TSH and a goiter, sometimes compressing and impairing breathing, or also a hyperthyroidism due to transplacental crossing of stimulating immunoglobulins with possibility of thyreotoxic crises and heart failure. The diagnosis could be made in utero in the presence of tachycardia or with T4 and TSH assays in the cord. In case of maternal hypothyroidism, usually the children have no problems and the risk of neonatal hypothyroidism is mostly present in premature infants if the maternal balance is poor (2 in 24 cases in our series). Finally, in the reference population, the risk of neonatal hypothyroidism remains 1 in 3600 and justifies systematic screening on the 5th day of life.

Profile of thyroid disorders in a referral centre in north India

From 1983-88, 157 patients were investigated in our clinic for thyroid disorders: 117 (75%) were hypothyroid, 10 (6%)-hyperthyroid, and 30 had euthyroid goiters. Average age of presentation of congenital hypothyroids was 4.07 years. Children with goitrous hypothyroidism (n = 19) were divided into: (i) thyroiditis: RAIU low and patchy, TMA positive: 2 children; (ii) dyshormonogenesis: RAIU high, family history positive, perchlorate discharge test positive: 2 children; (iii) iodine deficiency: RAIU high, urinary iodine low: 2 children, and (iv) cause unknown: RAIU normal or high, other investigations normal: 13 children. Ninety eight hypothyroid children without goiter were divided into 6 groups: (i) athyreosis: RAIU low, no thyroid tissue identifiable (n = 39); (ii) hypoplasia: RAIU low, gland small, in normal position (n = 7); (iii) ectopia: RAIU low, gland in ectopic position (n = 24); (iv) thyroiditis: TMA positive (n = 2); (v) iodine deficiency: low urinary iodine (n = 1); and (vi) cause unknown: RAIU and scan normal, other investigations normal and not done (n = 8). Proportionate short stature was present in 44.4% children. Twenty two children presented only with growth failure; 72% of them had dysgenetic glands. Early onset marked the group with hyperthyroidism (n = 10). Euthyroid goiter was present in 30 (19%). Hypothyroidism is still being diagnosed very late. All children with growth failure, even if proportionate, must have thyroid status evaluated.

[Congenital piriformo-thyroid fistula as a cause of recurrent suppurative thyroiditis]

A previously healthy five year old boy presented with suppurative, febrile thyroiditis of the left lobe with pronounced general and local signs of inflammation, normal thyroid function and lack of thyroid antibodies. Intravenous antibiotic therapy improved the condition quickly. Six and nine months later however recurrent left lobe thyroiditis occurred. Endoscopic examination showed an internal fistula from the left piriform sinus to the left thyroidal lobe which was cut out. The case report confirms previous communications, that recurrent suppurative thyroiditis is nearly always caused by a piriform sinus fistula, probably a fourth pharyngeal pouch remnant which can be cured surgically.

Prescribing in pregnancy. Thyroid disease

When treating thyroid disease, as with other conditions in pregnancy, one is concerned with the welfare of both mother and developing child. Thyroid disease causes few maternal problems; thyrotoxicosis in fact tends to improve in pregnancy, allowing medical management with lower drug doses than usual. Relapse of thyroid disease may occur postpartum, when transient hypo- and hyperthyroidism are relatively common. In contrast, the fetus and neonate are threatened in a number of ways by drugs given to the mother and by transplacental passage of maternal antibodies capable of inducing thyroid disease. Antithyroid drugs may cause fetal goitre with airway obstruction, and are associated with mild neonatal hypothyroidism. Thyroid antibodies in primary myxoedema and Hashimoto's thyroiditis are occasionally implicated in neonatal hypothyroidism and may even cause thyroid dysgenesis. Neonatal hyperthyroidism has a high morbidity and mortality and may have long-term skeletal effects such as craniosynostosis. Fetal problems may not be apparent at birth but may emerge in the next eight to ten days, especially in hyperthyroidism when the mother has been on treatment. Close monitoring throughout pregnancy and for the first ten days postpartum is required to minimize risks to the fetus and neonate. Most pregnancies associated with thyroid disease will have a successful outcome. If the occasional at-risk fetus is to be identified and treated successfully there should ideally be close cooperation between obstetrician, endocrinologist and paediatrician.

Free triiodothyronine and free thyroxin in sera of pregnant women and subjects with congenitally increased or decreased thyroxin-binding globulin

Concentrations of free thyroxin (T4) and free triiodothyronine (T3) were measured in sera from pregnant women, in subjects with congenitally increased or decreased thyroxin-binding globulin (TBG), and in euthyroid controls. Measured free hormone concentrations were compared with calculated values for free hormone derived from concentrations of total T4, total T3, and binding proteins. Measured and calculated concentrations of free T4 and free T3 were below normal in the pregnant subjects but were normal in subjects with congenital increases of TBG. The low concentrations of free hormone in pregnancy are at variance with the euthyroid status of these subjects. Measured free T4 was normal, but concentrations of free T3 were less in the euthyroid congenitally low-TBG group.

Advancing in tandem: clinical endocrinology and clinical chemistry

Here I review some of the recent accomplishments in clinical endocrinology and clinical chemistry, point out the direction of future work, and try to predict some of the advances of the next decade. Endocrinology, perhaps more than any other branch of clinical medicine, is rooted in biochemistry and physiology. Endocrinologists have been leaders in the development of methods, which have been adapted by clinical chemists for wider applications than those conceived originally. For the sake of brevity, I shall not recount the early history of endocrinology in this century--or the enormous progress since Starling coined the term "hormone" and stated the physiological role of these chemical messengers in 1905. Progress in endocrinology in recent years has been astounding.

Peripheral resistance to thyroid hormone in an infant

Peripheral resistance to thyroid hormone, a syndrome characterized by elevated serum total and free thyroid hormone levels and abnormal TSH suppression without manifestations of hyperthyroidism, was studied in a clinically euthyroid 6-month-old infant. Initial serum concentrations of T4, T3, and TSH were 22.1 micrograms/dl, 334 ng/dl, and 7.6 microunits/ml, respectively; infusion of synthetic TRH increased the serum TSH to 47.4 microunits/ml, an exaggerated response. Pituitary insensitivity to T3 was investigated by measuring these parameters in response to consecutive 7-day courses of increasing doses of T3. Four times the calculated replacement dose of T3 (40 micrograms/day) was required to normalize the serum T4 and the serum TSH response to TRH. After administration of 80 micrograms/day T3, the serum TSH response to TRH was virtually abolished, but no clinical signs of thyroid hormone excess were observed. High doses of T4 blunted the serum TSH response to TRH in a manner similar to T3. Prednisone also decreased the TSH response to TRH but had no effect on serum thyroid hormone concentrations. In an attempt to determine the mechanism of thyroid hormone resistance, specific nuclear T3 binding was compared in cultured skin fibroblasts from the patient and a normal infant. Normal fibroblast nuclei had a single binding site with a Ka of 3.1 X 10(9) M-1. In contrast, the Scatchard plot of the patient's T3 binding was curvilinear, compatible with a high affinity site that had a Ka (4.2 X 10(9) M-1) similar to that of the normal fibroblasts and a second low affinity site (Ka = 2.7 X 10(8) M-1). Supraphysiological concentrations of T3 elicited a dose-related increase in fibroblast glucose consumption, which was similar in cells from both the patient and from a normal infant. In conclusion, pituitary and peripheral resistance to thyroid hormone has been demonstrated in this infant, but despite the abnormality of nuclear T3 binding, the cellular mechanisms remain unclear.

[Peroxidase and human thyroid hormone synthesis disorders (author's transl)]

Thyroid peroxidase in involved in several steps of the biosynthesis of thyroid hormone utilizing H2O2: peroxidation of iodide to iodine, iodination of thyroglobulin (Tg) and coupling reaction leading to T4 and T3 formation. The peroxidase enzyme appears to be an heme protein containing a protoporphyrin IX, with binding sites for both iodide and tyrosine. Although the peroxidase is present in numerous cellular structure, iodination activity occurs primarily if not only at all, at the apical cell border. Lack of peroxidase activity or abnormal peroxidase has been described in isolated cases of congenital goiter with organification defect and a positive perchlorate test. However no change in enzymatic activity has been found in patients with Pendred's syndrome as compared to normal tissue. The deficiency of hormone synthesis observed in various benign diffuse thyroid disorders in certainly not due to a lack of peroxidase activity. In treated hyperthyroid patients, a high cellular activity is observed, especially at the apical cell border. In euthyroid patients with diffuse sporadic goiter, an increase of peroxidase activity is also observed. However, the cytochemical localization of the enzyme in goitrous thyroid gland shows that the peroxidase activity is mostly visualized around numerous lipoid structures; being concentrated in this particular site, the enzyme might preferentially oxidize lipids and consequently be less available for hormone synthesis. In euthyroid hot nodule, the peroxidase activity is normal. In cold nodule, a discrepancy between iodide oxidation and protein iodination has been found, suggesting that iodide peroxidation and iodination of tyrosine residues of Tg are two relatively independent processes although thyroid peroxidase catalyses both reactions. In contrast with the benign pathological conditions, the peroxidase activity is lower than normal in thyroid cancerous tissue.