Use of ultrasound in childhood thyroid disorders

Thyroid ultrasound in patients with Turner syndrome: influence of clinical and auxological parameters

OBJECTIVES

To determine thyroid volume and structure by ultrasound (US) in patients with Turner syndrome (TS) compared to healthy controls; to evaluate the frequency and characteristics of autoimmune thyroid disease (ATD) and its association with clinical and auxological parameters.

PATIENTS

73 patients and 93 height-matched healthy female controls in the same age range were included in the study.

RESULTS

Thirty-two TS patients (43.8%) presented ATD. They had a larger body mass index (BMI) and presented the 45,X karyotype more frequently than those without. They were older, with a higher prevalence of lymphoedema at birth and pterygium colli without statistical significance. Thyroid volume was 20% larger in the presence of ATD (p=0.037). A dyshomogeneous thyroid structure was observed in all patients with ATD and less frequently in those without (p=0.016). Dyshomogeneity in TS without ATD was also associated with older age (p<0.001), larger BMI (p=0.003) and larger thyroid volume (p=0.006). Six TS patients presented solitary thyroid nodules (5 benign nodules). We observed a significant interaction between diagnosis and height (p=0.035) and age (p=0.047), indicating that both age and height conditioned the observed differences in thyroid volume.

CONCLUSIONS

Most TS patients presented ATD with a normal thyroid function or subclinical hypothyroidism, without goiter. Dyshomogeneous thyroid structure was also observed in TS patients without ATD. In TS, the evaluation of thyroid volume according to chronological age does not seem to be efficient because of a link between height and thyroid volume. The prevalence of nodular thyroid disease is similar to that observed in the general population.

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.

Accuracy of ultrasonography to establish the diagnosis and aetiology of permanent primary congenital hypothyroidism

OBJECTIVE

To compare ultrasonography and 99mTc thyroid scintigraphy for the aetiologic diagnosis of permanent congenital hypothyroidism (CH).

STUDY DESIGN

Eighty-eight consecutive patients with CH were recruited at an endocrinology outpatient clinic and submitted to high-frequency ultrasonography and to 99mTc scintigraphy.

RESULTS

Seventy-six patients were diagnosed with permanent CH and 12 with transitory CH. The agreement between ultrasound and scintigraphy was very high (kappa coefficient = 0.866; P < 0.001) for the entire group. In permanent CH patients, ultrasonography identified 67 cases of dysgenesis (absence of thyroid gland in the usual anatomical location in 66 and hemiagenesis in one), and this diagnosis was confirmed by scintigraphy (absence of functional thyroid tissue in 43 and ectopia in 24). In the other nine permanent CH patients, the thyroid was in the usual anatomical location on ultrasonography but scintigraphy did not identify functional tissue in one patient. In the 12 transitory CH patients, a normally shaped thyroid was detected by ultrasound in the usual location, whereas scintigraphy showed absence of functional tissue in two identical twins and scarce concentration of isotope in a third patient.

CONCLUSION

Ultrasonography is an accurate method to establish the presence of dysgenesis and might be used as the first imaging tool in patients with CH, whereas scintigraphy should be used mainly to distinguish agenesis from ectopia. Further examination is required to differentiate permanent CH with a normally located and shaped gland from transitory hypothyroidism.

Normal thyroid volume by ultrasonography in healthy children

With the objective of creating standards for the volume of the thyroid gland by ultrasonography in the 0-16-year age group, thyroid volumes of 302 healthy children (150 boys, 152 girls) were measured by ultrasonography. The transverse (x), sagittal (y) and anteroposterior (z) lengths of the right and left lobes and isthmus were measured. Volumes of these were calculated by the ellipsoid volume formula [V = (pi/6) x x x y x z]. Statistical analysis was done using the Kruskal-Wallis and Student t tests. The cases were divided into six and eight groups by age and height, respectively. There was a significant positive correlation between thyroid volume, age, height and weight. Thyroid volumes in children of 12 years and over were significantly different from those in the younger age groups.

Multinodular goiter in children

OBJECTIVE

As multinodular goiter (MNG) is an uncommon pediatric disorder, we decided to evaluate the children with this diagnosis at our center to try to delineate better its etiology, the risk of malignancy and appropriate management strategies.

METHODS AND RESULTS

Eighteen patients (12 girls and 6 boys) were the subject of this retrospective review spanning a period of 20 years. All were previously well, except one, and none had had head or neck irradiation. Average age at diagnosis was 12.8 years. Four children belonged to two previously identified kindreds diagnosed with familial MNG. These families had members affected with multiple cases of non-medullary thyroid carcinoma (NMTC). All were euthyroid and had no symptoms. In eight of 18 patients, the clinical examination missed the presence of multiple nodules which were subsequently detected by ultrasound. Twelve patients had tissue diagnosis by fine needle aspirate cytology (FNAC) or surgery. Five of eight patients undergoing surgery had nodular hyperplasia, one had a follicular adenoma and one had a normal thyroid gland on histology. There was one patient with papillary carcinoma combined with nodular hyperplasia. Seven of the patients had evidence of antithyroid autoimmunity.

CONCLUSION

The etiology of pediatric MNG appears multifactorial including autoimmune and familial factors. We believe that previously healthy children can usually be managed conservatively. Ultrasound at the time of diagnosis and in follow up seems beneficial. Familial forms appear to warrant close follow up, given the apparent increased risk of malignancy. The risk of malignancy while low remains real.

Sonographic features of Hashimoto thyroiditis in childhood

Fifty-seven sonograms of 18 children with Hashimoto thyroiditis were retrospectively assessed. Thirty-three examinations (in 12 patients) showed thyroid glands which were more reflective than adjacent strap muscles, 22 studies (in eight patients) demonstrated glands of equal reflectivity and two examinations (in one child) depicted thyroid glands of lower reflectivity than muscle. The most frequent ultrasound appearance consisted of 2-5 mm echopenic lesions generally distributed throughout large poorly-defined hyperreflective glands. In serial examinations no correlation was found between laboratory indexes of thyroid status and sonographic findings.

Neonatal goiter: imaging findings in two children

Neonatal goiter is a rare cause of a neck mass and stridor. Often, the diagnosis can be made on clinical grounds exclusively, but there may be times when a neck mass becomes a diagnostic dilemma. There are several different imaging modalities available to the clinician that are useful in the rapid diagnosis of neonatal goiter. Presently, however, there is no definite algorithm for the workup of a neonatal neck mass. The two cases presented here demonstrate the imaging findings of plain film radiography, sonography, scintigraphy, and CT in neonatal goiter.

Fine-Needle Aspiration Biopsy: Use in Diagnosis and Management of Pediatric Thyroid Diseases

Fine-needle aspiration (FNA) biopsy of the thyroid is a reliable, safe, cost-effective, and widely used test. Its introduction and application have had a significant impact in the management of nodular thyroid diseases in adults. However, its utility in pediatric practice is not recognized or emphasized. During the last 12 years we performed 10,971 FNAs; 57 (0.5%) were in patients younger than age 17 years. Among 47 of these biopsies, 66% were benign, 15% were malignant, 6% were suspicious for malignancy and 13% were nondiagnostic. Biopsy was most often (96%) performed for the evaluation of diffuse or nodular goiter. The most common benign cytologic diagnosis was colloid goiter in 17 of 31 patients (55%) and Hashimoto's thyroiditis in 9 of 31 patients (29%). There were no false-positive results and there was one false-negative cytologic result. Among patients who had malignancy proved histologically, nine patients (75%) had papillary thyroid cancer. In this study, FNA biopsy was crucial in deferring surgery in 28 of 47 patients (60%). It is clear that the application of FNA biopsy prevents unnecessary surgery and improves surgical selection of patients with thyroid malignancy. On the basis of our extensive experience, we recommend FNA biopsy as the first diagnostic test for pediatric patients with nodular thyroid lesions.

Thyroid gland volume as measured by ultrasonography in preterm infants

The volume of the thyroid gland was determined by ultrasonography in 30 preterm infants (27-36 weeks' gestation) born in Madrid. Thyroid gland volume significantly increased (p < 0.01) with postnatal and postmenstrual age and was very well correlated with body weight, height and surface area (p < 0.01). Serum thyroid hormones 3,5,3'-triiodothyronine (T3) and free thyroxine (FT4) were linearly correlated with postnatal and postmenstrual age, thus T3 and FT4 levels were also correlated with thyroid gland volume (p < 0.05). We report measurements of the thyroid gland volume obtained by ultrasonography in this group of preterm infants. Quantitative determination of thyroid gland volume is more accurate for the diagnosis of goitre than clinical criteria. It is also interesting to determine the thyroid gland volume in the neonatal period when the thyroid is particularly hypersensitive to the effects of iodine deficiency and excess.

Sonographic imaging of the thyroid gland in congenital hypothyroidism

We have attempted to facilitate differential diagnosis of etiological types of congenital hypothyroidism using real-time ultrasonography. Sonography of the thyroid gland was performed on 418 normal children, and 23 patients with congenital hypothyroidism and hyperthyrotropinemia. The thyroid gland was imaged by transverse scanning at the neck; the maximum thickness and the maximum width of the right and left lobe were measured. On the basis of the normal thyroid gland size obtained from normal children, the thyroid gland image of the patients were classified into 4 types: large image, normal image, small image, and no image of the thyroid gland at the neck: no image of the thyroid gland indicated agenesis or ectopia; large thyroid gland image indicated goitorous hypothyroidism. On the other hand, normal or small thyroid gland image probably included mild or transient forms of hypothyroidism, and transient hyperthyrotropinemia; these 2 types required further examination to complete the diagnosis. We concluded that real-time ultrasonography of the thyroid gland was a useful diagnostic imaging technic for patients who revealed elevated serum thyrotropin on neonatal mass-screening.

Iodine-123 scintigraphy in the evaluation of pediatric thyroid disorders: a ten year experience

Few studies have been published that describe the role of scintigraphy in the evaluation of the spectrum of pediatric thyroid disorders. Between 1978 and 1987, we studied 280 children with iodine-123 (123I) scintigraphy. Clinical information and follow-up were available in 246. We analyzed the indications for referral and determined whether the information obtained with this technique was useful in subsequent management. Indications for scintigraphy included hypothyroidism, neck masses, hyperthyroidism, and miscellaneous reasons. Scintigraphy was helpful in distinguishing anatomic from functional causes of hypothyroidism. It reliably identified the location of the thyroid gland in patients with neck masses. The functional status of thyroid nodules was readily assessed and was important in directing further treatment. Scintigraphy added little to the management of children with post-irradiation hypothyroidism without a palpable nodule, patients with Hashimoto thyroiditis or Graves disease when the clinical diagnosis was straightforward.

Determination of thyroid volume by ultrasound from the neonatal period to late adolescence

The volume of the thyroid gland was determined by ultrasonography in 256 euthyroid subjects aged 0-20 years in Brussels, an area with borderline iodine intake (median urinary iodine: 6.8 micrograms/dl). The volume of each lobe was calculated separately using the formula of an ovoid (Depth x Length x Width x pi/6). The total thyroid volume was obtained by summation of the volume of both lobes. In neonates, mean volume (SD) was 0.84 (0.38) ml and the distribution was asymmetric, skewed towards elevated values (median: 0.76 ml); the volume was best correlated with body surface area (P less than 0.01). Thyroid volume significantly increased (P less than 0.001) until the age of 8 without being influenced by sex and thereafter varied widely: it increased from 2.7 (0.8) ml in prepubertal subjects aged 8-11 years to 11.6 (4.4) ml in late pubertal aged greater than 17 years. This increase was significantly correlated not only with chronological age but also with pubertal stage and seemed to happen early, with the onset of the first clinical signs of puberty. At all ages, the volume of the right lobe was slightly higher than the left lobe but the difference was not significant.

Sonographic imaging of the thyroid in children

High-resolution sonographic imaging of thyroid disorders in paediatrics has become an extremely accurate method and is being more frequently used. The need for scintigraphy has therefore dramatically decreased. The anatomy and sonographic morphology of the thyroid gland (normal findings, variants) in infants and children are presented, as are patterns of thyroid disorders and respective algorithms of diagnostic imaging.

Neonatal hypothyroidism: comparison of radioisotope and ultrasound imaging in 54 cases

Fifty-four neonates with congenital hypothyroidism identified by the North East and North West Thames Regional hypothyroid screening programme between January 1985 and December 1987 were investigated with radioisotope (Tc99m) and ultrasound scans of the thyroid before treatment with 1-thyroxine was commenced. Compared with the radioisotope scans, ultrasound identified normally sited thyroid tissue in only 7 out of 10 cases, and ectopic thyroid tissue in only 5 out of 26 cases. Three out of 18 cases with no isotope uptake in the neck appeared to have normally sited tissue on ultrasound scan. We conclude that in our hands ultrasound of the neck is of only limited value in the assessment of young infants with congenital hypothyroidism.

Contribution of thyroid ultrasound and serum calcitonin to the diagnosis of congenital hypothyroidism

To elucidate the role of thyroid ultrasound (TU) in the diagnosis of congenital hypothyroidism (CH), we compared 1) TU and thyroid scintigraphy (TS) in 6 CH newborns and 2) TU results in the 6 CH newborns, in 8 newborns with "false positive" results at screening, in 13 CH children aged 2 mo to 12 yr treated since the neonatal period and in 235 controls aged 0-12 yr.

RESULTS

1) In all 6 CH newborns with no thyroid uptake at TS, TU evidenced small posterior hyperechogenic masses in the thyroid area [Vol: 322 +/- 180 (SD) mm3]; 2) In all normal controls and in the 8 "false positive" cases at screening TU showed normal thyroid structures. The thyroid volume was 831 +/- 383 mm3 in normal newborns and progressively increased with age. In the older CH children, TU also demonstrated the hyperechogenic masses, but their volume barely increased with age: as a consequence, the difference between the volume of the masses in CH patients and the thyroid tissue in controls, already significant in newborns (p less than 0.01), markedly increased with age. The exact nature of these masses is unknown; they could represent poorly vascularized ultimobranchial remnants containing the calcitonin - secreting cells: this hypothesis is supported by our finding that serum concentrations of calcitonin (measured by a sensitive extraction method) (mean +/- SD, pg/ml) were lower in the CH patients (2.9 +/- 1.5) than in controls (13.0 +/- 6.9; p less than 0.001) at birth. In conclusion, in all cases of CH, TU showed abnormal structures in the thyroid area. TU and TS provide complementary information in the diagnosis of CH, and TU should be routinely performed in all newborns suspected of CH to avoid unnecessary use of TS in unaffected infants.

Neonatal hypothyroidism: recent developments

This chapter summarizes recent developments in the field of sporadic congenital hypothyroidism (CH) and transient neonatal hypothyroidism detected by systematic neonatal thyroid screening. The incidence of CH detected by screening is about 1 in 4000 births in North America, Europe and Australia; it is lower (1 in 7000) in Japan. The aetiology remains unknown; genetic and environmental factors are possibly involved. The role of autoimmunity has recently been studied extensively. Antithyroglobulin (ATA) and antimicrosomal antibodies are not involved; the possible role of thyroid growth blocking antibodies (TGBAb) of maternal origin remains controversial. Evaluation of clinical signs, bone maturation, serum T4 and the position and size of the thyroid by scintigraphy at the time of diagnosis in CH infants are important because these variables are related to the final psychoneuro-intellectual prognosis, irrespective of the adequacy of therapy. Thyroid echography always distinguishes a normal thyroid in the neonate but cannot define precisely the type of thyroid dysgenesis, if present (e.g. ectopic, athyreosis). The determination of serum Tg contributes to the diagnosis but its specificity and sensitivity are insufficient to replace thyroid scintigraphy. Therapy by LT4, at an initial dose of 25-50 micrograms/day in full-term infants, is universally recommended. The objective of therapy is to reach as soon as possible and to maintain serum concentrations of total and free T4 at the upper limits of normal for age. Serum TSH should decrease as rapidly as possible below 20 microU/ml and then remain within the normal range. Persistent hyperthyrotropinaemia in spite of normal serum T4 has to be avoided as it could represent poor compliance and/or insufficient therapy. Programmes of 10 to 14 years of follow-up of CH infants have now shown that the neuropsychointellectual prognosis of CH is excellent in all cases when therapy and psychosocial environment are adequate. Although still within the normal range, IQ is somewhat lower in spite of appropriate therapy in cases of severe prenatal hypothyroidism and some transient and correctable neurological signs occasionally occur. In Western countries transient neonatal hypothyroidism is usually due to iodine deficiency or iodine excess; the newborn infant is hypersensitive to the antithyroid action of an extraphysiological supply of iodine. TSH binding inhibitor immunoglobulins (TBII) of maternal origin occasionally cause transient neonatal hypothyroidism. In developing countries with severe iodine deficiency and endemic goitre, the incidence of thyroid failure in the newborn can be as high as 1 in 10.(ABSTRACT TRUNCATED AT 400 WORDS)

Cold thyroid nodules in childhood: is surgery always necessary?

In children who present with a cold thyroid nodule the current recommendation is that surgery immediately be performed in view of the high probability of thyroid cancer. Because the incidence of thyroid cancer in children may be decreasing and because extensive experience has been gained in adults with thyroid echography and fine-needle aspiration cytology, we evaluated three consecutive children with cold thyroid nodules by means of these non-surgical techniques. The diagnoses were: thyroid cancer in one patient, thyroid abscess in one and haemorrhagic cyst of the thyroid in one. In the latter two patients, fine-needle aspiration was both diagnostic and therapeutic. We conclude that thyroid echography and fine-needle aspiration of thyroid nodules deserve more extensive evaluation in the paediatric age group.

Ultrasound imaging in diffuse thyroid disorders of children

The diagnosis of diffuse thyroid disorders in children is based mainly on hormone and antibody determinations and a cytologic sample taken by aspiration biopsy. The cytologic sample is not always obtainable in small children or when the thyroid gland is not enlarged. Thyroid antibodies lead to diagnosis only in a proportion of cases. Gamma imaging is not recommended in children because of the radiation risk. The aim of this study was to demonstrate that ultrasound imaging can detect diffuse thyroid disorders in children. Ultrasound images were abnormal in 92% of all subjects; they were abnormal in 97% of cases with thyroiditis and in most cases ultrasound was diagnostic. With antibody determinations, only 60% of the cases of thyroiditis could be diagnosed. Ultrasound imaging--a risk-free method--should be included in the diagnostic investigation of thyroid disorders.