Clinical experience with radioactive iodine in the treatment of childhood and adolescent Graves' disease

Long-term outcome of treatments for Graves disease in the children and adolescent population

BACKGROUND

Several studies were conducted over the years to find a significant association between non-surgical therapies such as Antithyroid Drug (ATD) Therapy and Radio-iodo therapy (RIT) with Graves' disease (GD) remission and relapse. However, these investigations did not have a specific focus on the age category of children and adolescents. Hence, this Research is performed to assess the association of non-surgical therapy (ATD and RIT) with Graves' disease (GD) remission and relapse in the children and adolescent population.

DESIGN

A systematic review and meta-analysis of observational studies and clinical trials were carried out.

METHODS

A systematic search of PubMed, EMBASE, and SCOPUS from their inception till April 2022 was performed for studies stating an association between ATD therapy and GD remission and relapse in participants 1-17 years old. The random-effects model was used in the meta-analysis to provide a pooled proportion of both primary outcomes. The quality and each study were assessed using the Newcastle Ottawa Scale (NOS).

RESULT

From 6195 studies searched from the databases, only 16 relevant articles remained after a detailed evaluation. These studies, having a total of 2557 patients aged 5-17 years, were involved in the analysis with a pooled estimate showing a significant association of ATD therapy with GD remission (Estimate: 0.400, 95% Confidence interval: 0.265-0.535; I^2 = 98.16%) and with GD relapse (Estimate: 0.359, 95% Confidence interval: 0.257-0.461; I^2 = 98.26%). Subgroup analyses were conducted to assess the remission rate of different therapies suggesting that antithyroid drugs play a significant role in the remission of the patients. All included studies were classified as moderate quality.

CONCLUSION

Following meta-analysis suggested that the ATD used in the analysis is effective in remitting GD in the children and adolescents population. Nevertheless, long-term RIT therapy and thyroidectomy leads to hypothyroidism. Still, large-sample, and high-quality studies targeting ATDs' use in children and adolescents with long-term surveillance of prognosis are needed.

Ultrasound determination of pediatric thyroid mass

BACKGROUND

Radioiodine therapy for Graves disease can be achieved with dosing based on estimated thyroid gland mass. Thyroid mass can be estimated using linear ultrasound measurements, and conversion factors for volume and density. The choice of conversion factors could impact estimated thyroid mass and thus administered radioiodine dose.

OBJECTIVE

The objective of this study was to define the relationship between thyroid mass estimated by ultrasound and measured thyroid mass following thyroidectomy.

MATERIALS AND METHODS

This was a retrospective, exempt study that included patients < 18 years of age with < 6 months between thyroid ultrasound and thyroidectomy January 2010-June 2020. Thyroid dimensions by ultrasound, thyroid mass at thyroidectomy and histopathological diagnosis were collected. Published conversion factors were used to estimate thyroid volume with conversion to mass using a density of 1.05 g/cm³. Pearson correlations and Bland-Altman difference analyses were used to define the relationship between estimated mass and specimen weight. Linear regression was used to calculate an optimal conversion factor for estimating thyroid mass.

RESULTS

We included 86 patients, 67 female (78%), with a mean age of 14.5 ± 3.15 years. Mass estimated using all tested conversion factors had similar strong, positive correlation with specimen weight (r = 0.95). The mean difference between thyroid mass estimated by ultrasound and measured mass ranged from - 0.34 g (conversion factor = 0.523) to 1.69 g (conversion factor = 0.554). The optimal simplified factor for estimation of thyroid mass for the study sample was 0.537.

CONCLUSION

All published conversion factors for estimating thyroid mass based on linear ultrasound measurements produce good estimates of thyroid mass. Errors in estimated mass are less than 2 g on average.

Radioiodine treatment of pediatric Graves disease: a multicenter review

BACKGROUND

There is no standardized approach to iodine-131 (I-131) therapy of hyperthyroidism in pediatric Graves disease. This prevents systematic study of outcomes.

OBJECTIVE

To characterize current radioiodine dosing and define therapeutic outcomes at multiple institutions that use ultrasound to measure thyroid size to guide I-131 ablation of Graves disease.

MATERIALS AND METHODS

This was a retrospective cohort study conducted at three institutions. The three sites collected demographic data, thyroid volume measured by ultrasound (mL), pre-ablation radioiodine uptake, I-131 activity administered, and outcomes at 6 and 12 months for children younger than 18 years of age treated with I-131 between November 2004 and October 2019. Comparisons of continuous variables were performed using the Mann-Whitney U test.

RESULTS

Sixty-nine patients (mean age: 14.5±2.5 years) were included, 59 (85.5%) of whom were female. The mean administered I-131 radioiodine activity was 12.5 mCi (463 MBq) (range: 3.8-29.9 mCi [141-1,106 MBq]). At 6 months post-ablation, 54 (80.5% of 67) patients were hypothyroid, 8 (11.9% of 67) were euthyroid and 5 were hyperthyroid. Two of the five hyperthyroid patients had become euthyroid at 12 months. At 12 months, 1 previously euthyroid patient was hyperthyroid. Administered activity per mL of thyroid tissue adjusted for 24-h uptake was lower (0.18 mCi [6.7 MBq] x %/mL vs. 0.31 mCi [11.5 MBq] x %/mL, P=0.0054) for patients who remained hyperthyroid at 6 months.

CONCLUSION

There is substantial variability in administered activity for radioiodine ablation of Graves disease in children. Efforts to standardize practice should start by standardizing administered activity guided by measurement of thyroid size by ultrasound. Our results and those of previous studies suggest the need for administered activities ≥0.25 mCi [9.3 MBq] x %/mL of thyroid tissue.

Patient Compliance With Surveillance of Thyroid Nodules Classified as Atypia of Undetermined Significance

OBJECTIVE

To determine whether thyroid nodule surveillance compliance is influenced by patient demographics or plan type.

STUDY DESIGN

Retrospective case series from 2010 to 2018.

SETTING

United States Military Health System.

METHODS

There were 481 patients with a thyroid nodule fine-needle aspiration classified as atypia of undetermined significance for whom treatment and follow-up information were available. Demographic information and surveillance plan type were extracted from the medical record and statistical analysis was performed to determine whether these characteristics influenced compliance rates.

RESULTS

A total of 289 nodules were surveilled and 192 diagnostic lobectomies were performed. An initial surveillance plan was documented in 93% (268/289) and 86% (231/268) complied. The most common plans were repeat biopsy in 78% (210/268) or ultrasound in 20% (53/268). A second plan was documented in 88% (204/231) of those who complied with the first. The most common second plans were ultrasound in 87% (178/204) or repeat biopsy in 8% (17/204). Compliance with the second plan was 64% (130/204), significantly lower than with the first (OR 3.6, 95% CI: [2.3, 5.6], P < .0001). Only 45% (130/289) were surveilled twice. Age and gender did not significantly affect compliance rates. Compliance with primary care ultrasound surveillance was 40% (21/52), significantly lower than with a specialist (77% [137/179]; OR 4.8, 95% CI: [2.5, 9.3, P < .0001).

CONCLUSION

Compliance with surveillance of thyroid nodules classified as atypia of undetermined significance was poor in this military cohort. Ultrasound surveillance by a specialist may be more reliable than with primary care.

Hyperthyroidism in adolescents

The term 'hyperthyroidism' refers to a form of thyrotoxicosis due to inappropriate high synthesis and secretion of thyroid hormone(s) by the thyroid. The leading cause of hyperthyroidism in adolescents is Graves' disease (GD); however, one should also consider other potential causes, such as toxic nodular goitre (single or multinodular), and other rare disorders leading to excessive production and release of thyroid hormones. The term 'thyrotoxicosis' refers to a clinical state resulting from inappropriate high thyroid hormone action in tissues, generally due to inappropriate high tissue thyroid hormone levels. Thyrotoxicosis is a condition with multiple aetiologies, manifestations, and potential modes of therapy. By definition, the extrathyroidal sources of excessive amounts of thyroid hormones, such as iatrogenic thyrotoxicosis, factitious ingestion of thyroid hormone, or struma ovarii, do not include hyperthyroidism. The aetiology of hyperthyroidism/and thyrotoxicosis should be determined. Although the diagnosis is apparent based on the clinical presentation and initial biochemical evaluation, additional diagnostic testing is indicated. This testing should include: (1) measurement of thyroid-stimulating hormone receptor (TSHR) antibodies (TRAb); (2) analysis of thyroidal echogenicity and blood flow on ultrasonography; or (3) determination of radioactive iodine uptake (RAIU). A 123I or 99mTc pertechnetate scan is recommended when the clinical presentation suggests toxic nodular goitre. A question arises regarding whether diagnostic workup and treatment (antithyroid drugs, radioiodine, surgery, and others) should be the same in children and adolescents as in adults, as well as whether there are the same goals of treatment in adolescents as in adults, in female patients vs in male patients, and in reproductive or in postreproductive age. In this aspect, different treatment modalities might be preferred to achieve euthyroidism and to avoid potential risks from the treatment. The vast majority of patients with thyroid disorders require life-long treatment; therefore, the collaboration of different specialists is warranted to achieve these goals and improve patients' quality of life.

Long-Term Outcomes of Radioiodine Therapy for Juvenile Graves Disease with Emphasis on Subsequently Detected Thyroid Nodules: A Single Institution Experience from Japan

OBJECTIVE

To investigate the long-term outcomes of radioiodine therapy (RIT) for juvenile Graves disease (GD) and the ultrasonographic changes of the thyroid gland.

METHODS

All of 117 juvenile patients (25 males and 92 females, aged 10 to 18 [median 16] years) who had undergone RIT for GD at our clinic between 1999 and 2018 were retrospectively reviewed. Each RIT session was delivered on an outpatient basis. The maximum 131I dose per treatment was 13.0 mCi, and the total 131I dose per patient was 3.6 to 29.8 mCi (median, 13.0 mCi). 131I administration was performed once in 89 patients, twice in 26, and three times in 2 patients. Ultrasonography of the thyroid gland was regularly performed after RIT. The duration of follow-up after the initial RIT ranged from 4 to 226 (median 95) months.

RESULTS

At the latest follow-up more than 12 months after RIT (n = 111), the patients' thyroid functions were overt hypothyroidism (91%), subclinical hypothyroidism (2%), normal (5%), or subclinical hyperthyroidism (2%). New thyroid nodules were detected in 9 patients, 4 to 17 years after initial RIT. Patients with newly detected thyroid nodules underwent RIT with lower doses of 131I and had larger residual thyroid volumes than those without nodules. None of the patients were diagnosed with thyroid cancer or other malignancies during the follow-up period.

CONCLUSION

Over a median follow-up period of 95 months (range, 4 to 226 months), RIT was found to be effective and safe in juvenile GD. However, cumulative evidence from further studies is required to confirm the long-term safety of RIT for juvenile GD.

ABBREVIATIONS

ATD = antithyroid drug; GD = Graves disease; KI = potassium iodide; LT4 = levothyroxine; MMI = methimazole; PTU = propylthiouracil; RAIU = radio-active iodine uptake; RIT = radioiodine therapy; 99mTc = technetium-99m; TSH = thyrotropin.

Diagnosis and management of hyperthyroidism from prenatal life to adolescence

Hyperthyroidism in children is a rare heterogeneous syndrome characterized by excessive thyroid hormone production. Its manifestations differ according to disease severity. For all forms of hyperthyroidism, treatment aims to restore a euthyroid state, enabling the child to demonstrate appropriate metabolism, growth, and neurocognitive development. Graves' disease is the most frequent cause of hyperthyroidism in children. Treatment modalities include antithyroid drugs, with the advantage that prolonged treatment for several years can be followed by freedom from medical intervention in about 40-50% of cases. It may also be treated with radioactive iodine or, less frequently, thyroidectomy, these more radical treatments both necessitating subsequent lifelong levothyroxine treatment. Particular care is required in the management of pregnant women with Graves' disease. Fetal and neonatal forms of hyperthyroidism are transient and rare, but nevertheless serious. Here, we provide an overview of the best approach to hyperthyroidism diagnosis and management, from fetal development to adolescence.

Treatment of Graves' disease in children: The Portuguese experience

INTRODUCTION

Graves' disease (GD) is an autoimmune thyroid disease, common in adults but rare in children. The best therapeutic approach remains controversial.

OBJECTIVES

To ascertain the current treatment of pediatric GD in Portugal and to assess the clinical and biochemical factors that determine definitive/long-term remission after treatment with antithyroid drugs (ATDs).

PATIENTS AND METHODS

A retrospective analysis of data about pediatric GD treatment collected from a nationwide survey conducted by the Portuguese Society of Pediatric Endocrinology and Diabetology from May to August 2013. Population was categorized based on sex, age, use of ATDs, dosage, treatment duration, adverse reactions, thyrotropin receptor-stimulating antibody (TRAB) titer, remission and remission/relapse rates, and definitive treatment, and divided into group A (with ongoing treatment) and group B (with treatment stopped). Group B was subdivided into 'Remission', 'Remission+relapse' and 'No remission' subgroups based on the course of disease. The same parameters were compared between both groups.

RESULTS

Survey response rate was 77%; 152 subjects, 116 female, mean age at diagnosis 11.23±3.46 years. They all started treatment with ATDs, 70.4% with thiamazole, with a mean treatment duration of 32.38±28.29 months, and 5.9% had adverse effects. Remission rate was 32.6%. Lower age at diagnosis correlated with higher remission rates. Treatment duration was longer when propylthiouracil was used. Initial TRAB titer was significantly higher in the 'No remission' group. Surgery and radioiodine were used as second-line treatments.

CONCLUSION

Our study results were similar to those reported in the literature. Age and TRAB titer were identified as potential clinical and laboratory determinants of remission. Based on risk/benefit analysis, it was concluded that treatment should be individualized based on age, accessibility to treatments, and physician's experience.

MANAGEMENT OF ENDOCRINE DISEASE: Arguments for the prolonged use of antithyroid drugs in children with Graves' disease

Graves' disease is an autoimmune disorder. It is the leading cause of hyperthyroidism, but is rare in children. Patients are initially managed with antithyroid drugs (ATDs), such as methimazole/carbimazole. A major disadvantage of treatment with ATD is the high risk of relapse, exceeding 70% of children treated for duration of 2 years, and the potential major side effects of the drug reported in exceptional cases. The major advantage of ATD treatment is that normal homeostasis of the hypothalamus-pituitary-thyroid axis may be restored, with periods of drug treatment followed by freedom from medical intervention achieved in approximately 40-50% of cases after prolonged treatment with ATD, for several years, in recent studies. Alternative ablative treatments such as radioactive iodine and, less frequently and mostly in cases of very high volume goiters or in children under the age of 5 years, thyroidectomy, performed by pediatric surgeons with extensive experience should be proposed in cases of non-compliance, intolerance to medical treatment or relapse after prolonged medical treatment. Ablative treatments are effective against hyperthyroidism, but they require the subsequent administration of levothyroxine throughout the patient's life. This review considers data relating to the prognosis for Graves' disease remission in children and explores the limitations of study designs and results; and the emerging proposal for management through the prolonged use of ATD drugs.

Guidelines for the treatment of childhood-onset Graves' disease in Japan, 2016

Purpose behind developing these guidelines: Over one decade ago, the “Guidelines for the Treatment of Graves’ Disease with Antithyroid Drug, 2006” (Japan Thyroid Association (JTA)) were published as the standard drug therapy protocol for Graves’ disease. The “Guidelines for the Treatment of Childhood-Onset Graves’ Disease with Antithyroid Drug in Japan, 2008” were published to provide guidance on the treatment of pediatric patients. Based on new evidence, a revised version of the “Guidelines for the Treatment of Graves’ Disease with Antithyroid Drug, 2006” (JTA) was published in 2011, combined with the “Handbook of Radioiodine Therapy for Graves’ Disease 2007” (JTA). Subsequently, newer findings on pediatric Graves’ disease have been reported. Propylthiouracil (PTU)-induced serious hepatopathy is an important problem in pediatric patients. The American Thyroid Association’s guidelines suggest that, in principle, physicians must not administer PTU to children. On the other hand, the “Guidelines for the Treatment of Graves’ Disease with Antithyroid Drug, 2011” (JTA) state that radioiodine therapy is no longer considered a “fundamental contraindication” in children. Therefore, the “Guidelines for the Treatment of Childhood-Onset Graves’ Disease with Antithyroid Drug in Japan, 2008” required revision.

Radiofrequency ablation for postsurgical thyroid removal of differentiated thyroid carcinoma

Differentiated thyroid carcinoma (DTC) is the most common endocrine malignancy. Surgical removal with radioactive iodine therapy is recommended for recurrent thyroid carcinoma, and the postsurgical thyroid removal is critical. This study evaluated the clinical values of radiofrequency ablation (RFA) in the postsurgical thyroid removal for DTC. 35 DTC patients who had been treated by subtotal thyroidectomy received RFA for postsurgical thyroid removal. Before and two weeks after RFA, the thyroid was examined by ultrasonography and (99m)TcO4 (-) thyroid imaging, and the serum levels of free triiodothyronine (FT3), free thyroxin (FT4), thyroid stimulating hormone (TSH) and thyroglobulin (Tg) were detected. The efficacy and complications of RFA were evaluated. Results showed that, the postsurgical thyroid removal by RFA was successfully performed in 35 patients, with no significant complication. After RFA, the average largest diameter and volume were significantly decreased in 35 patients (P > 0.05), and no obvious contrast media was observed in ablation area in the majority of patients. After RFA, the serum FT3, FT4 and Tg levels were markedly decreased (P < 0.05), and TSH level was significantly increased (P < 0.05). After RFA, radioiodine concentration in the ablation area was significantly reduced in the majority of patients. The reduction rate of thyroid update was 0.69±0.20%. DTC staging and interval between surgery and RFA had negative correlation (Pearson coefficient = -0.543; P = 0.001), with no obvious correlation among others influential factors. RFA is an effective and safe method for postsurgical thyroid removal of DTC.

Influence of prior carbimazole on the outcome of radioiodine therapy in pediatric and adolescent Graves' disease

OBJECTIVE OF THE STUDY

Therapeutic options for pediatric Graves' disease (PGD) include antithyroid drug therapy (ATD) as the first line and radioiodine (I-131) therapy as the second line of treatment. To date, controversies persist regarding the true effect of prior ATD in the outcome of I-131 therapy in PGD. This study evaluated the effect of prior carbimazole treatment on the outcome of I-131 therapy in PGD.

METHODS

This is a retrospective study covering the years 1995-2012, with a median follow-up of 75 months. Records of 114 children (84 girls and 30 boys, age range: 5-20 years, mean 24-h radioiodine uptake, 58%) who had clinically and biochemically proven Graves' disease irrespective of prior ATD therapy were included. All patients were treated with fixed doses of 5 mCi (185 MBq) I-131 for Graves' disease; 74 had undergone prior carbimazole treatment (group 1) and 40 were drug naive (group 2). The endpoint of follow-up was stable euthyroid or hypothyroid in patients. The effect of prior carbimazole treatment on the outcome of I-131 therapy in PGD patients was evaluated. The success of radioiodine therapy was defined as the cure of hyperthyroidism. Variables were analyzed to identify the potential predictive factors for euthyroidism/hypothyroidism after treatment.

RESULTS

The cure rate was 70% in group 1 and 83% in group 2 with a single dose of radioiodine (P=0.299). The success rate achieved at the end of 1-year follow-up in group 1 and group 2 was 81 and 87%, respectively (P=0.401). No independent predictor was associated with success or failure of treatment. At the median follow-up of 75 months (range: 12-216 months), 76% of patients were hypothyroid on replacement doses of levothyroxine and 24% still continued to be euthyroid.

CONCLUSION

Prior carbimazole treatment does not alter the outcome of radioiodine therapy in PGD.