Radioactive iodine for thyrotoxicosis in childhood and adolescence: treatment and outcomes

Thyroid volume is the key predictor of hyperthyroidism remission after radioactive iodine therapy in pediatric patients

Graves' disease (GD) is the leading cause of hyperthyroidism in pediatric patients. Radioactive iodine therapy (RAIT) is widely used to treat GD. However, it is still unclear exactly what determines the efficacy of RAIT in childhood and adolescence. The objective of our study was to reveal the most significant predictors of the efficacy of RAIT in pediatric GD patients. A single-center prospective observational exploratory study enrolled 144 pediatric patients (124 females and 20 males) between 8 and 18 years of age who underwent dosimetry-guided RAIT for GD for the first time. The estimated parameters included sex, age, thyroid volume, thyroid stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone receptor antibodies (TRABs) at baseline and 12 months after RAIT, 10- to 20-min 99mTc thyroid uptake (%), maximum thyroid 131I uptake (%), specific 131I uptake (MBq/g), and therapeutic activity of 131I (MBq), which was limited to 1100 MBq. The Fisher's exact test, Mann-Whitney U-test, Wilcoxon signed-rank test, ROC analysis, and the Youden index were used for statistical analysis. Twelve months after RAIT, 119 patients (83%) successfully achieved remission, 6 patients (4%) had euthyroidism, and hyperthyroidism persisted in 19 patients (13%). Thyroid volume decreased from 17.6 [14.6; 24.1] to 9.3 [7.6; 13.3] mL 12 months after the treatment (p < 0.001). The main predictor that showed a statistically significant difference between the groups of patients who achieved and did not achieve remission of GD hyperthyroidism after RAIT was the initial thyroid volume. Using the Youden index, the optimal cut-off point for the initial thyroid volume at 45.4 mL was determined.     Conclusion: The dosimetry-guided RAIT in pediatric GD patients was 83% effective at 12 months after the treatment, and the initial thyroid volume of less than 45.4 mL was the most important predictor of RAIT success. Other predictors identified in our work included FT4 levels, TRABs levels, 99mTc-pertechnetate uptake, and specific 131I uptake. What is Known: •Radioiodine therapy is a common, effective, and safe treatment for pediatric patients with Graves' disease. What is New: •The initial thyroid volume in pediatric GD patients is an important predictor of achieving hypothyroidism following radioiodine therapy. If the thyroid volume is less than 45.4 ml, radioiodine therapy limited to 1100 MBq will be effective definitive treatment.

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.

[Definitive treatment of Graves' disease in children]

BACKGROUND

Hyperthyreoidism due to Graves' disease is a rare disorder in pediatric practice. There is 2 treatment options in Graves' disease: medical treatment and definitive treatment, including surgery and radioactive iodine. Each method has its advantages and disadvantages. If medical therapy is ineffective the choice between radical treatment method is raised: radioactive iodine or total thyroidectomy. In this research we analyze treatment outcomes in pediatric Graves' disease patients after different radical treatment methods.

AIM

Comparative analysis of radical treatment outcomes in pediatric patients with Graves' disease.

MATERIALS AND METHODS

Retrospective and prospective one-center research of 122 patients with Graves' disease after radical treatment (between 2016 and 2021)RESULTS: The mean age was 13.5±3,5 year at the moment of examination. Patients were divided into 2 groups due to the radical treatments method: 1 group (n=60) were children after surgical treatment, 2 group (n=62) - after radioactive iodine. The mean dose of medical treatment in these groups did not reliably differ (p=0,06), duration of the medical treatment was reliably longer in patients after radioactive iodine (p=0,024). Graves' orbitopathy was diagnosed in 58 patients (47,5%) and met equally often in both groups, but active stage of Graves' orbitopathy was diagnosed only in patients from the 1st group. Thyroid size was reliable bigger in patients from the 1st group (p=0,004), and thyroid gland nodes were diagnosed only in patients from 1st group (p=0,0007).

CONCLUSION

RI can be considered an effective and safe treatment for GD. The effectiveness of RI depends on the volume of the thyroid gland; according to the results of the constructed ROC curve, the risk of repeated RI is higher with a volume of more than 55 cm3. Also radioactive iodine is undesirable if there is signs of ophatalmopathy due to its possible deterioration. According to the results of the study hypoparathyroidism after surgical treatment was diagnosed in 20%, recurrent laryngeal nerve injury was diagnosed after surgical treatment in 5% of patients. In patients with identified nodular goiter according to the results of ultrasound, surgical treatment is preferable due to the impossibility of excluding thyroid cancer.

Success rate of radioactive iodine treatment for children and adolescent with hyperthyroidism

PURPOSE

To assess the success rate of first dose radioiodine for treatment of hyperthyroidism in children and adolescent.

METHODS

This is a retrospective data analysis of children and adolescent with hyperthyroidism who received radioiodine (RAI) therapy from January 2013 to December 2017. Age, gender, family history of hyperthyroidism, duration of anti-thyriod drugs (ATDs) treatment, rapid turnover status, 2 h and 24 h I-131 radioiodine uptake (RAIU), thyroid volume, and treatment dose were also analyzed. The goal of RAI therapy was to achieve hypothyroidism within 3-6 months after treatment. Treatment result was evaluated at 6 months after treatment and divided into 2 groups: treatment success (hypothyroid and euthyroid) and treatment failure (hyperthyroid). The same parameters were compared between both groups.

RESULTS

32 hyperthyroid patients, 26 female with mean age at treatment of 13.84 ± 1.83 years. All patients had prior treatment with ATDs, with a median treatment duration of 32.5 months (range 2-108). The median estimated thyroid gland size was 24.62 g, range 9.29-72.8. RAI doses ranged from 4.1 to 29.9 mCi (median dose = 7.54 mCi). Significant difference in 24-h I-131 uptake and RI status was demonstrated. Successful treatment rate after single dose of therapeutic I-131 was 65.63%.

CONCLUSION

With the I-131 dose of 220 μCi/g of thyroid tissue, successful treatment rate after single dose of therapeutic I-131 was 65.63%. RAI therapy with I-131 dose of 250-400 μCi/g of thyroid tissue might be suitable in patients with medical failure from ATDs. Possible role of RI as the predictor for RAI therapy failure are needed to investigate in both adult and children clinical settings.

[Predictors of the efficacy of radioiodine therapy of Graves' disease in children and adolescents]

RATIONALE

Insufficient world-wide clinical experience in radioiodine therapy (RIT) for Graves' disease (GD) in children and adolescents, and limited knowledge of the predictors of RIT efficacy.

AIMS

Analysis and identification of the most significant predictors of the efficacy of RIT in children and adolescents with Graves' disease.

MATERIALS AND METHODS

A total of 55 patients (48 females and 7 males) aged from 8 to 18 years receiving primary RIT for GD were enrolled. RIT planning was based on the dosimetric method. Analyzed parameters included gender, age, ultrasound thyroid volume before and 6 months after treatment, the presence of endocrine ophthalmopathy, duration of antithyroid drug (ATD) therapy, relapse of thyrotoxicosis after ATD dose reduction, blood fT3, fT4 and TSH levels initially and at 1, 3, 6 months after treatment, TSH receptor Ab initially and at 3 and 6 months after treatment, thyroid 99mTc-pertechnetate uptake at 10-20 minutes (%), maximum thyroid 131I uptake (%), specific 131I uptake (MBq/g) and therapeutic 131I activity (MBq). Fisher exact test, non-parametric Mann-Whitney test, Wilcoxon signed-rank test, logistic regression modelling, ROC-analysis, proportional hazard model (the Cox regression), the Kaplan-Meier method and log-rank test were used for statistical analysis as appropriate.

RESULTS

Six months after RIT, hypothyroidism was achieved in 45 (81.8%), euthyroid state - in 2 (3.6%), and in 8 (14.6%) patients thyrotoxicosis persisted. On univariate statistical analysis, the smaller thyroid volume, higher fT4 and lower TSH receptor Ab levels, lower 99mTc-pertechnetate uptake and higher specific 131I uptake were associated with hypothyroidism. On multivariate logistic regression analysis, the older patient's age (p=0.011), smaller thyroid volume (p=0.003) and higher fT4 (p=0.024) were independent predictors of RIT efficacy. Thyroid volume was also the only variable associated with achievement of hypothyroidism in time after RIT (p=0.011).

CONCLUSION

The efficacy of dosimetry-based RIT in children and adolescents with GD 6 months after treatment was 81.2%. Older patients' age, smaller thyroid volume and higher fT4 level were independent predictors of therapy success. Smaller thyroid volume was also a predictor of the favorable time-related outcome. Statistical models obtained in this work may be used to prospectively estimate the chance of efficient RIT for GD in pediatric patients.

Radioactive iodine therapy for pediatric Graves' disease: a single-center experience over a 10-year period

Introduction Only about 30% of pediatric patients with Graves' hyperthyroidism achieve remission with medical therapy, and therefore radioactive iodine (RAI) therapy is often used as a definitive treatment. Although the goal of RAI is permanent hypothyroidism, this is not consistently achieved. We conducted a chart review to determine the factors associated with the success of RAI. We also tried to determine optimal follow-up post RAI and if there was an optimal L-thyroxine dose that would normalize the hypothyroid state quickly. Methods This is a retrospective chart review of Graves' patients who underwent RAI between 2008 and 2017. We included age, sex, time from diagnosis, thyroid gland size, total dose of I-131 and dose in μCi/g of thyroid tissue. Patients were grouped based on outcome and analyzed using univariate and multivariate logistic regression. Follow-up thyroid levels post RAI and after starting l-thyroxine were analyzed. Results There were 78 ablations including six repeat ablations. Seventy-three percent became hypothyroid, 23% remained overtly or subclinically hyperthyroid, and 4% were euthyroid. Smaller thyroid size (36.5 vs. 47.4 g; p = 0.037) and higher dose of I-131 (242 vs. 212 μCi/g thyroid tissue; p = 0.013) were associated with a higher likelihood of hypothyroidism. Most patients remained hyperthyroid at 1 month post RAI, but by 3 months the majority became hypothyroid. There was no clear L-thyroxine dose that normalized hypothyroidism quickly. Conclusions An I-131 dose close to 250 μCi/g of thyroid tissue has a higher likelihood of achieving hypothyroidism. Testing at 2-3 months after RAI is most helpful to confirm response to RAI.

Measurement of cumulative radiation exposure to children and adolescents in contact with outpatients treated with low dose radioactive iodine (131I)

BACKGROUND

Radiation exposure from patients treated with radioactive iodine (¹³¹I) represents a radiation hazard to children and adolescents, representing the most vulnerable group of household contacts. Our aim was to calculate the cumulative radiation exposure (CRE) figures to children and adolescents sharing the same home with outpatients treated with low-dose ¹³¹I. The secondary aim was to study the demographic and educational factors that may significantly affect radiation exposure to them.

RESULTS

The whole number of household contacts less than 18 years was 99, out of them 49 ≤ 12 years. CRE level to children and adolescents ranged from 79 to 934 uSv. The mean, median, and 75th percentile figures were 284 ± 178 uSv, 215 uSv, and 334 uSv, respectively. The compliance of this group of contacts to radiation exposure constraint (1 mSv) was 100%. All CRE values were below this figure with 75% of them below half of this constraint. Thirteen adolescents from 12 to 18 years and 17 mothers of 23 household contacts ≤ 12 years got radiation safety instructions (RSI) directly from a radiation safety officer (RSO). This group had a significantly lower mean CRE value (184 ± 93 uSv) compared to those who got RSI from the patient or from other family members (298 ± 185 uSv) with a significant p value.

CONCLUSION

The compliance of adolescents and children to the 1-mSv radiation exposure constraint is 100%. It is advised for adolescents and mothers of children in contact with ¹³¹I-treated patients to get direct RSI from the RSO, which is the only factor associated with significantly lower radiation exposure figures.

Graves' disease following allogenic hematopoietic stem cell transplantation for severe aplastic anemia: case report and literature review

BACKGROUND

Similar autoimmune processes (defective T-cell function) take place during the pathogenesis of aplastic anemia (AA) and Graves' disease (GD). Antithyroid drugs used for the management of GD may induce AA and GD may occur following treatment of severe aplastic anemia (SAA).

CASE PRESENTATION

Clinical and laboratory investigations were performed for an 11-year-and-2-month-old girl who was referred for bilateral exophthalmus and abnormal thyroid function tests. She had been diagnosed as having severe acquired AA at the age of 8 years and had been treated with allogenic hematopoietic stem cell transplantation from her healthy human leukocyte antigen-matched sibling donor. Clinical examination revealed a weight of 32.6 kg (-0.88 standard deviation [SD] score); height, 145.7 cm (-0.14 SD score); body mass index 15.5 kg/m2 (-1.01 SD score); heart rate, 110/min; blood pressure, 128/74 mmHg; bilateral exophthalmos and an enlarged thyroid gland. The laboratory workup showed hemoglobin of 11.1 g/dL; white blood cells, 7500/mL; platelets, 172,000/mL; free thyroxine (FT4), 4.80 ng/dL (normal, 0.5-1.51); free triiodothyronine (FT3), 17.7 pg/mL (normal, 2.5-3.9); thyrotropin (TSH), 0.015 mIU/mL (normal, 0.38-5.3); antithyroglobulin peroxidase (TPO) antibody, 61.7 IU/mL (normal, 0-9); antithyroglobulin (TG) antibody, <0.9 IU/mL (normal, 0-4) and thyrotropin (TSH) receptor antibodies 14 U/L (normal, 0-1). Doppler ultrasonography showed diffuse enlargement of the thyroid gland and increased vascularity. She was treated with methimazole (0.6 mg/kg/day). L-thyroxine treatment was also needed (50 μg/day). Thrombocytopenia developed during follow-up. A thyroidectomy was performed for definitive treatment at the 14th month of treatment.

CONCLUSIONS

The association of hyperthyroidism and AA in the pediatric age group is rare. The long-term use of antithyroid drugs and radioactive iodine should be avoided due to their hematologic toxic side effects.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS, AMERICAN COLLEGE OF ENDOCRINOLOGY, AND ASSOCIAZIONE MEDICI ENDOCRINOLOGI MEDICAL GUIDELINES FOR CLINICAL PRACTICE FOR THE DIAGNOSIS AND MANAGEMENT OF THYROID NODULES--2016 UPDATE

Thyroid nodules are detected in up to 50 to 60% of healthy subjects. Most nodules do not cause clinically significant symptoms, and as a result, the main challenge in their management is to rule out malignancy, with ultrasonography (US) and fine-needle aspiration (FNA) biopsy serving as diagnostic cornerstones. The key issues discussed in these guidelines are as follows: (1) US-based categorization of the malignancy risk and indications for US-guided FNA (henceforth, FNA), (2) cytologic classification of FNA samples, (3) the roles of immunocytochemistry and molecular testing applied to thyroid FNA, (4) therapeutic options, and (5) follow-up strategy. Thyroid nodule management during pregnancy and in children are also addressed. On the basis of US features, thyroid nodules may be categorized into 3 groups: low-, intermediate-and high-malignancy risk. FNA should be considered for nodules ≤10 mm diameter only when suspicious US signs are present, while nodules ≤5 mm should be monitored rather than biopsied. A classification scheme of 5 categories (nondiagnostic, benign, indeterminate, suspicious for malignancy, or malignant) is recommended for the cytologic report. Indeterminate lesions are further subdivided into 2 subclasses to more accurately stratify the risk of malignancy. At present, no single cytochemical or genetic marker can definitely rule out malignancy in indeterminate nodules. Nevertheless, these tools should be considered together with clinical data, US signs, elastographic pattern, or results of other imaging techniques to improve the management of these lesions. Most thyroid nodules do not require any treatment, and levothyroxine (LT4) suppressive therapy is not recommended. Percutaneous ethanol injection (PEI) should be the first-line treatment option for relapsing, benign cystic lesions, while US-guided thermal ablation treatments may be considered for solid or mixed symptomatic benign thyroid nodules. Surgery remains the treatment of choice for malignant or suspicious nodules. The present document updates previous guidelines released in 2006 and 2010 by the American Association of Clinical Endocrinologists (AACE), American College of Endocrinology (ACE) and Associazione Medici Endocrinologi (AME).