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

The EANM guideline on radioiodine therapy of benign thyroid disease

This document provides the new EANM guideline on radioiodine therapy of benign thyroid disease. Its aim is to guide nuclear medicine physicians, endocrinologists, and practitioners in the selection of patients for radioiodine therapy. Its recommendations on patients' preparation, empiric and dosimetric therapeutic approaches, applied radioiodine activity, radiation protection requirements, and patients follow-up after administration of radioiodine therapy are extensively discussed.

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.

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.

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.