Reduction in thyroid volume after radioiodine therapy of Graves' hyperthyroidism: results of a prospective, randomized, multicentre study

Nomogram construction and evaluation for predicting non-remission after a single radioactive iodine therapy for Graves' hyperthyroidism: a retrospective cohort study

Background

Radioactive iodine (RAI) therapy is a widely used treatment for Graves' Hyperthyroidism (GH). However, various factors can impact the non-remission rate of GH after single RAI therapy. This study aimed to develop an online dynamic nomogram to assist physicians in providing personalized therapy for GH.

Methods

Data from 454 GH patients who received RAI therapy were retrospectively reviewed and included in the present study. The univariate and multivariate analysis were conducted to investigate and identify independent influencing factors. The nomogram was developed based on the training cohort to explore non-remission rates. Finally, the reliability and accuracy of the constructed nomogram model were verified in the validation cohort via the calibration, receiver operating characteristic (ROC) curve, and decision curve analysis (DCA).

Results

24-hours radioactive iodine uptake (RAIU24h), effective half-life (Teff), total iodine dose (TID) and iodine dose per gram of thyroid tissue (IDPG) were independent predictors. The nomogram had a high C-index 0.922 (95% CI: 0.892-0.953), for predicting non-remission. The calibration curves demonstrated excellent consistency between the predicted and the actual probability of non-remission. ROC analysis showed that the AUC of the nomogram model and the four independent factors in the training cohort were 0.922, 0.673, 0.760, 0.761, and 0.786, respectively. The optimal cutoff value for the total nomogram scores was determined to be 155. A total score of ≥155 indicates a higher likelihood of non-remission after a single RAI therapy for GH, whereas a score below 155 suggests a greater likelihood of remission. Additionally, the DCA curve indicated that this nomogram had good clinical utility in predicting non-remission.

Conclusion

An online nomogram was constructed with good predictive performance, which can be used as a practical approach to predict and assist physicians in making personalized therapy decisions for GH patients.

Predictive factors for the outcome of radioiodine therapy in patients with benign thyroid diseases

PURPOSE

Radioiodine therapy (RIT) of benign thyroid diseases is an established therapy. This study aimed to identify factors predictive for outcome in patients with non-toxic goiter (NTG), unifocal (UFA), multifocal (MUFA) or diffuse autonomy (DISA) and Graves' disease (GD).

METHODS

Retrospective analysis of 205 patients with benign thyroid disease (54 NTG, 46 MUFA, 24 DISA, 26 UFA, 55 GD) who underwent RIT. Follow up time was 12 months for determining treatment outcome.

RESULTS

The type of disease was predictive for volume reduction after 12 months (NTS 66%, DISA 67%, MUFA 58%, UFA 51%, GD 71%, p<0.001) and post-treatment hypothyroidism (NTS 48%, DISA 33%, MUFA 15%, UFA 15%, p=0.006). Initial volume, intra-therapeutic uptake and intra-therapeutic half-life were independent prognostic factors for volume reduction 12 months after RIT. In patients with NTG, UFA, MUFA, DISA post-treatment hypothyroidism was significantly correlated with extent of volume reduction 12 months after RIT, achieved dose, higher pre-therapeutic TSH values and younger age. Two different strategies for pre-therapeutic dosimetry used in MUFA showed no differences regarding the therapeutic outcome. In GD, effective half-life, initial volume and Graves' ophthalmopathy were predictive for treatment failure.

CONCLUSION

Reduction of thyroid volume and the percentage of hypothyroid patients one year after RIT was primarily dependent on the type of disease. In MUFA and DISA we could identify volume reduction after 3 months as a reliable predictor for hypothyroidism while in patients with GD a short intra-therapeutic half-life, a large pre-therapeutic volume and active Graves' ophtalmopathy were relevant predictors for treatment failure suggesting an intensified follow-up scheme in these patients.

Approach to the Patient: Management and the Long-term Consequences of Graves' Disease in Children

In children, Graves' disease (GD) is the most common cause of hyperthyroidism. Most pediatric patients with GD will not go into lasting remission, even following many years of antidrug therapy. Thus, most pediatric patients will require radioactive iodine (RAI) or surgery. When antithyroid drugs are used, methimazole is the drug of choice. When methimazole is used in children, up to 20% will have minor adverse reactions and serious adverse events occur in up to 1%. RAI is an effective form of therapy when the thyroid size is less than 80 g. Because of concerns of whole-body radiation exposure, it is recommended that RAI be avoided in children under 5 years of age, and dosages less than 10 mCi be used between 5 and 10 years of age. Surgery is an effective treatment in children if performed by a high-volume thyroid surgeon. Because of the scarcity of high-volume pediatric thyroid surgeons, a multidisciplinary approach using pediatric surgeons and endocrine surgeons can be considered. Whereas there is a trend toward long-term antithyroid drug therapy in adults, for several reasons, this approach may not be practical for children. Determining the optimal treatment for the pediatric patient with GD, requires consideration of the risks and benefits relating to age and likelihood of remission.

Is There Any Need for Adjusting 131I Activity for the Treatment of High Turnover Graves' Disease Compared to Normal Turnover Patients? Results from a Retrospective Cohort Study Validated by Propensity Score Analysis

Purpose

To compare ¹³¹I-therapy outcomes in high turnover and normal turnover Graves' disease patients and predict optimal first ¹³¹I activity for high turnover patients.

Methods

Retrospective cohort design (1:2) validated by propensity score analysis. Cohort 1, high turnover (2-h RAIU/24-h RAIU ≥ 1), n = 104, and cohort 2, normal turnover (ratio < 1), n = 208, patients were compared for post ¹³¹I outcome. The cure was defined as a combined euthyroid and stable hypothyroid state following ¹³¹I treatment. Logistic regression analysis was used for identifying prognostic factors. The propensity score was applied; 77 matched pairs (1:1 ratio) of high and normal turnover patients were selected as a validation set.

Results

First ¹³¹I cure rates of 28% in high turnover and 66% in normal turnover groups (p = 0.001) were noted. The therapy cycles (median, 2 vs. 1) and cumulative ¹³¹I activity (median, 15 vs. 7 mCi) were required to cure hyperthyroidism in cohort 1 and cohort 2, respectively. Age (> 44 years), higher grade of goitre, and 2-h RAIU (> 37%) were associated with ¹³¹I therapy failure. The high turnover patients needed a factor of 1.5-2 times more ¹³¹I activity to achieve a similar cure rate compared to the normal turnover patients. The first-dose cure rate was 31% vs. 60% by propensity score analysis (n = 154), no way different (28% vs.66%) from the whole group of 312 patients.

Conclusion

High turnover Graves' disease patients, if administered standard ¹³¹I activity, the outcomes shall be poor. To improve the success rate, ¹³¹I activity should be increased by 1.5 to 2 times in the high turnover patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13139-020-00674-3.

Color Duplex Doppler US can Follow up the Response of Radioiodine in Graves' Disease by Evaluating the Thyroid Volume and Peak Systolic Velocity

PURPOSE

 The objective of this study was to prove the efficacy of Doppler ultrasonography (US-Doppler) in the follow-up of patients with GD treated with radioactive iodine.

METHODS

 97 patients (77 female and 20 male) with a mean age of 42 years (SD ± 15) and with prior diagnosis of GD were treated with radioiodine. In total, 88.5 % achieved euthyroidism or hypothyroidism after treatment. The study was documented before treatment and one, three, and six months after treatment with radioactive iodine (131I) by a single investigator. The volume, echogenicity, echotexture and vascularization of the glands as well as the peak systolic velocity (PSV) of the inferior thyroid arteries were evaluated and compared with the laboratory data.

RESULTS

 Thyroid volume and PSV had a statistically significant correlation with hormone levels (p < 0.05). The mean pre-dose therapeutic thyroid volume was 43.01 ± 3.88 cm³ and was 11.58 ± 11.26 cm³ 6 months after treatment. The mean PSV before 131I was 90.06 ± 44.13 cm/s and decreased significantly over time (p < 0.001). Six months after the therapeutic dose, the mean PSV was 32.95 ± 16.36 cm/s. However, the subjective parameters did not have a significant correlation with the normalization of the thyroid hormones.

CONCLUSION

 Doppler US was useful for monitoring the therapeutic response of GD patients after treatment with radioiodine by evaluating the thyroid volume and peak systolic velocity.

Serum Thyroid Hormone Balance in Levothyroxine Monotherapy-Treated Patients with Atrophic Thyroid After Radioiodine Treatment for Graves' Disease

Background: Some studies reported that among athyreotic patients on levothyroxine (LT4) after total thyroidectomy, patients with normal serum thyrotropin (TSH) levels had mildly low serum free triiodothyronine (fT3) levels, whereas patients with mildly suppressed serum TSH levels had normal serum fT3 levels. The reduction of the thyroid volume (TV) after radioiodine treatment for Graves' disease is well known; however, a few studies evaluated thyroidal function including serum triiodothyronine (T3) levels of hypothyroid patients on LT4 after radioiodine treatment in detail. Methods: We retrospectively studied 446 patients treated with LT4 for radioiodine-induced hypothyroidism and who had undergone ultrasonography. We compared serum fT4 and fT3 levels in hypothyroid patients on LT4 who presented an atrophic thyroid change after radioiodine treatment, with those in the euthyroid matched control group with intact thyroids. We also stratified patients with normal TSH levels according to TV and evaluated serum thyroid hormone levels. Results: In 356 of 446 (80%) patients, TV was lower than the lower limit of the 95% reference range of controls. Excluding 43 patients with high serum TSH levels, we assessed thyroid function test results in 313 patients with atrophic thyroid glands. Of these cases, eight patients with strongly suppressed TSH levels had serum fT3 levels that were significantly higher than those in controls (p < 0.001). Overall, 27 patients with mildly suppressed TSH levels had serum fT3 levels equivalent to those in controls (p = 0.386), whereas 278 patients with normal TSH levels had serum fT3 levels that were significantly lower than those in controls (p < 0.001). We also assessed fT3 levels relative to TV in 326 patients with normal TSH levels. Of these cases, in 267 patients with TV less than 5 mL and in 46 patients with TV between 5 and 10 mL, serum fT3 levels were significantly lower than those in controls (p < 0.001). In 13 patients with TV more than 10 mL, serum fT3 levels were equivalent to those in controls (p = 0.844). Conclusions: Serum thyroid hormone balance in most patients on LT4 after radioiodine treatment for Graves' disease was similar to that in athyreotic patients on LT4. Mild TSH suppression with LT4 is needed to achieve normal fT3 levels in such patients.

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.

Controversies in the management of Graves' disease in children

Graves' disease (GD) is the most prevalent cause of thyrotoxicosis in children. Because spontaneous and lasting resolution of this condition occurs in only a minority of patients, most pediatric patients with GD will need radioactive iodine treatment (¹³¹I) or thyroidectomy. Whereas the medication propylthiouracil (PTU) had been used in the past, only methimazole (MMI) should be now used in children, as PTU is associated with an unacceptable risk of liver failure. However, MMI may be associated minor and major side effects, which may be minimized using lower doses. An area of controversy involves the optimal duration of antithyroid drug (ATD) therapy. For some children, the prolonged use of antithyroid drugs is a valid approach, but for most, this will not increase the chance of remission. When ¹³¹I is administered, dosages should be greater than 150 uCi/gm of thyroid tissue, with higher dosages needed for larger glands. Considering that there will be low-level whole body radiation exposure associated with ¹³¹I, this treatment is viewed as controversial by some and should be avoided in young children. When surgery is performed, near-total or total thyroidectomy is the recommended procedure. Complications for thyroidectomy in children are considerably higher than in adults. Thus, an experienced thyroid surgeon is needed when children have surgery. Overall, when different treatment options for GD are considered, the benefits, risks and viewpoints of the family need to be considered and discussed in full.

2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis

BACKGROUND

Thyrotoxicosis has multiple etiologies, manifestations, and potential therapies. Appropriate treatment requires an accurate diagnosis and is influenced by coexisting medical conditions and patient preference. This document describes evidence-based clinical guidelines for the management of thyrotoxicosis that would be useful to generalist and subspecialty physicians and others providing care for patients with this condition.

METHODS

The American Thyroid Association (ATA) previously cosponsored guidelines for the management of thyrotoxicosis that were published in 2011. Considerable new literature has been published since then, and the ATA felt updated evidence-based guidelines were needed. The association assembled a task force of expert clinicians who authored this report. They examined relevant literature using a systematic PubMed search supplemented with additional published materials. An evidence-based medicine approach that incorporated the knowledge and experience of the panel was used to update the 2011 text and recommendations. The strength of the recommendations and the quality of evidence supporting them were rated according to the approach recommended by the Grading of Recommendations, Assessment, Development, and Evaluation Group.

RESULTS

Clinical topics addressed include the initial evaluation and management of thyrotoxicosis; management of Graves' hyperthyroidism using radioactive iodine, antithyroid drugs, or surgery; management of toxic multinodular goiter or toxic adenoma using radioactive iodine or surgery; Graves' disease in children, adolescents, or pregnant patients; subclinical hyperthyroidism; hyperthyroidism in patients with Graves' orbitopathy; and management of other miscellaneous causes of thyrotoxicosis. New paradigms since publication of the 2011 guidelines are presented for the evaluation of the etiology of thyrotoxicosis, the management of Graves' hyperthyroidism with antithyroid drugs, the management of pregnant hyperthyroid patients, and the preparation of patients for thyroid surgery. The sections on less common causes of thyrotoxicosis have been expanded.

CONCLUSIONS

One hundred twenty-four evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice.

The Sonographic Features of the Thyroid Gland After Treatment with Radioiodine Therapy in Patients with Graves' Disease

The aim of the study was to describe the typical sonographic features of the thyroid gland in patients with Graves' hyperthyroidism after radioiodine therapy (RIT). Thirty patients (21 female and 9 male) with a mean age of 53 y (standard deviation [SD] ± 11.3) and with previous Graves' disease who had been successfully treated with RIT were enrolled in the study. All were hypothyroid or euthyroid after treatment. The thyroid ultrasound was carried out by a single experienced operator with an 8-MHz linear transducer. Volume, vascularity, echogenicity and echotexture of the glands were noted. The presence of nodules and lymph nodes was also documented. The mean volumes of the right lobe were 2.4 mL ± 2.9 SD (0.6-14) and the left lobe were 1.8 mL ± 1.9 SD (0.4-9.1), with a mean total volume of 4.2 mL ± 4.7 SD (1.3-19.1). Of those who had a pre-treatment ultrasound (23%), the percentage reduction in volume was 87% (p < 0.05); 93% of the glands were hypovascular, with the remaining 7% showing normal vascularity. The glands were hyperechoic and of coarse echotexture. Overall, the sonographic features of the post-RIT gland included a significantly reduced mean total volume of 4.2 mL, hypovascularity, coarse echotexture and hyperechogenicity.

The evidence base for the use of internal dosimetry in the clinical practice of molecular radiotherapy

Molecular radiotherapy (MRT) has demonstrated unique therapeutic advantages in the treatment of an increasing number of cancers. As with other treatment modalities, there is related toxicity to a number of organs at risk. Despite the large number of clinical trials over the past several decades, considerable uncertainties still remain regarding the optimization of this therapeutic approach and one of the vital issues to be answered is whether an absorbed radiation dose-response exists that could be used to guide personalized treatment. There are only limited and sporadic data investigating MRT dosimetry. The determination of dose-effect relationships for MRT has yet to be the explicit aim of a clinical trial. The aim of this article was to collate and discuss the available evidence for an absorbed radiation dose-effect relationships in MRT through a review of published data. Based on a PubMed search, 92 papers were found. Out of 79 studies investigating dosimetry, an absorbed dose-effect correlation was found in 48. The application of radiobiological modelling to clinical data is of increasing importance and the limited published data on absorbed dose-effect relationships based on these models are also reviewed. Based on National Cancer Institute guideline definition, the studies had a moderate or low rate of clinical relevance due to the limited number of studies investigating overall survival and absorbed dose. Nevertheless, the evidence strongly implies a correlation between the absorbed doses delivered and the response and toxicity, indicating that dosimetry-based personalized treatments would improve outcome and increase survival.

Pediatric Graves' disease: management in the post-propylthiouracil Era

The most prevalent cause of thyrotoxicosis in children is Graves’ disease (GD), and remission occurs only in a modest proportion of patients. Thus most pediatric patients with GD will need treatment with radioactive iodine (RAI; ¹³¹I) or surgical thyroidectomy. When antithyroid drugs (ATDs) are prescribed, only methimazole (MMI) should be administered, as PTU is associated with an unacceptable risk of severe liver injury. If remission does not occur following ATD therapy, ¹³¹I or surgery should be contemplated. When ¹³¹I is administered, dosages should be greater than 150 uCi/gm of thyroid tissue, with higher dosages needed for large glands. Considering that there will be low-level whole body radiation exposure associated with ¹³¹I, this treatment should be avoided in young children. When surgery is performed near total or total-thyroidectomy is the recommended procedure. Complications for thyroidectomy in children are considerably higher than in adults, thus an experienced thyroid surgeon is needed when children are operated on. Most importantly, the care of children with GD can be complicated and requires physicians with expertise in the area.

[Efficacy of treatment with I(131) in paediatric Graves disease]

INTRODUCTION

Radioiodine is an important therapeutic option in young patients with Grave's disease (GD). In the United States it is a widespread therapy, but in Europe its use in paediatrics is still controversial.

AIM

To report our experience in radioiodine therapy of paediatric GD patients and analyse its effectiveness and safety.

PATIENTS AND METHODS

We retrospectively studied our paediatric population (<18 years of age) with GD, diagnosed from 1982 to 2012. A curative option was offered to patients who did not respond to anti-thyroid drug (AT) at puberty. We analysed, the patient characteristics, TSH, T4, T3 and thyroid antibodies levels, AT response, remission post I(131), side effects, and hypothyroidism rates.

RESULTS

A total of 50 patients were diagnosed with GD from 1982 to 2012. All patients received AT as initial treatment (mean duration: 35.3±25.9 months). Permanent remission was achieved in 46%. Thyroidectomy was performed in 5 patients, and 14 patients received I(131) (mean dose: 10.9±1.09 mCi). Remission with I(131) was obtained in 100%. The rate of permanent hypothyroidism was 90%. There was no progression of ophthalmopathy or side effects in any patients treated with I(131.)

CONCLUSION

Radioiodine treatment of paediatric GD patients is safe, leads to complete remission at the expense of hypothyroidism, and does not exacerbate ophthalmopathy. It can be considered in patients older than 5 years, who do no not respond to AT or with significant side effects with this medication.

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

OBJECTIVE

The aim of the present study was to evaluate the outcome of radioiodine treatment in thyrotoxicosis in childhood and adolescence.

METHODS

This was a retrospective study of 27 patients (ages 7.2- 19.8 years) with a diagnosis of thyrotoxicosis who received iodine-131 (I-131) treatment from January 2007 to December 2011 in the Nuclear Medicine Division, Department of Radiology, Faculty of Medicine, Chiang Mai University. Gender, duration of antithyroid drug (ATD) treatment, 24-hour I-131 uptake, thyroid weight, total dose and number of treatments with I-131, and thyroid status at 6 months after treatment were recorded.

RESULTS

The outcomes of 27 patients (85.2% female, 14.8% male) treated with radioactive iodine were analyzed to assess the effectiveness of therapy as related to dose and gland size. All children and adolescents received 150 µCi of I-131/g of thyroid tissue (n=27). Six 6 months after treatment, 44.5% of the patients were hyperthyroid, 14.8% were euthyroid, and 40.7% were hypothyroid. Of the 12 cases with hyperthyroidism, 2 cases needed a second dose of I-131 treatment, and they finally reached a hypothyroid state. The patients were classified into 2 groups according to treatment success (euthyroid and hypothyroid) and treatment failure (hyperthyroid). There were no significant differences in age, gender, duration of ATD treatment, 2- and 24-hour I-131 uptake, thyroid weight, and total I-131 dose between these two groups.

CONCLUSIONS

Radioiodine treatment is safe and effective for thyrotoxicosis in childhood and adolescence. It is suitable as a good second-line therapy for patients with severe complications, those who show poor compliance, and those who fail to respond to ATD treatment.

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

BACKGROUND/AIMS

Treatments for Graves' disease (GD) in children and adolescents include oral antithyroid drugs (ATDs), near total thyroidectomy, and radioactive iodine (RAI). ATDs remain the preferred choice in this age group, but because persistent remission occurs in 30% of cases, RAI is becoming a common option for definitive therapy.

METHODS

We performed a review of 65 medical records of GD patients under age 19 years who were followed between 1985 and 2005.

RESULTS

The prevalence of GD was higher in females (3:1) and during puberty (for both genders). If no remission was detected during ATD treatment, RAI was indicated when the following criteria were present: non-compliance, relapse, or side effects that were related to ATDs, large goiter, and long-term use of ATDs. The majority of patients developed hypothyroidism within 6 months after RAI. A progressive higher dose regimen was implemented in the last 10 years of the study period. A second RAI dose was necessary in eight cases. During the follow-up period, three pregnancies occurred. One patient with a thyroid nodule and benign cytology was detected.

CONCLUSIONS

RAI therapy is effective and safe in the treatment of GD in children and adolescents.

Radioiodine therapy in benign thyroid diseases: effects, side effects, and factors affecting therapeutic outcome

Radioiodine ((131)I) therapy of benign thyroid diseases was introduced 70 yr ago, and the patients treated since then are probably numbered in the millions. Fifty to 90% of hyperthyroid patients are cured within 1 yr after (131)I therapy. With longer follow-up, permanent hypothyroidism seems inevitable in Graves' disease, whereas this risk is much lower when treating toxic nodular goiter. The side effect causing most concern is the potential induction of ophthalmopathy in predisposed individuals. The response to (131)I therapy is to some extent related to the radiation dose. However, calculation of an exact thyroid dose is error-prone due to imprecise measurement of the (131)I biokinetics, and the importance of internal dosimetric factors, such as the thyroid follicle size, is probably underestimated. Besides these obstacles, several potential confounders interfere with the efficacy of (131)I therapy, and they may even interact mutually and counteract each other. Numerous studies have evaluated the effect of (131)I therapy, but results have been conflicting due to differences in design, sample size, patient selection, and dose calculation. It seems clear that no single factor reliably predicts the outcome from (131)I therapy. The individual radiosensitivity, still poorly defined and impossible to quantify, may be a major determinant of the outcome from (131)I therapy. Above all, the impact of (131)I therapy relies on the iodine-concentrating ability of the thyroid gland. The thyroid (131)I uptake (or retention) can be stimulated in several ways, including dietary iodine restriction and use of lithium. In particular, recombinant human thyrotropin has gained interest because this compound significantly amplifies the effect of (131)I therapy in patients with nontoxic nodular goiter.

Surgical management of pediatric Graves' disease: an effective definitive treatment

PURPOSE

The optimal treatment for pediatric Graves' disease (GD) is controversial. Antithyroid drugs are often used initially, but they are associated with a high failure rate. Therefore alternative therapies have become important. In the present study, we analyze our institution's experience regarding the safety and efficacy of thyroid surgery among pediatric patients with GD.

METHODS

This is a retrospective chart review of 27 pediatric patients (age ≤ 18 years) with GD who underwent thyroid surgery between 1991 and 2009 at a single academic Institution. We recorded preoperative, intraoperative, and short-term postoperative data.

RESULTS

All 27 patients were initially treated with thionamides. The high rate of hyperthyroidism relapse after discontinuation of medical treatment, age < 5 years, adverse reaction to medical therapy, severe ophthalmopathy, and patient preference justified the final decision to proceed with surgery as definitive therapy. All patients underwent total thyroidectomy. We had no mortality; surgical complications were rare: 4 (14.8 %) cases of transient hypocalcemia, 1 (3.7 %) of permanent hypocalcemia, 3 (11.1 %) of transient RLN neuropraxia, and 2 (7 %) of keloid scar. No bleeding, permanent RLN palsy or relapse hyperthyroidism were reported.

CONCLUSIONS

Surgical therapy for pediatric GD performed by experienced thyroid surgeons is a safe, definitive and cost-effective treatment.

Hyperthyroidism and other causes of thyrotoxicosis: management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists

OBJECTIVE

Thyrotoxicosis has multiple etiologies, manifestations, and potential therapies. Appropriate treatment requires an accurate diagnosis and is influenced by coexisting medical conditions and patient preference. This article describes evidence-based clinical guidelines for the management of thyrotoxicosis that would be useful to generalist and subspeciality physicians and others providing care for patients with this condition.

METHODS

The development of these guidelines was commissioned by the American Thyroid Association in association with the American Association of Clinical Endocrinologists. The American Thyroid Association and American Association of Clinical Endocrinologists assembled a task force of expert clinicians who authored this report. The task force examined relevant literature using a systematic PubMed search supplemented with additional published materials. An evidence-based medicine approach that incorporated the knowledge and experience of the panel was used to develop the text and a series of specific recommendations. The strength of the recommendations and the quality of evidence supporting each was rated according to the approach recommended by the Grading of Recommendations, Assessment, Development, and Evaluation Group.

RESULTS

Clinical topics addressed include the initial evaluation and management of thyrotoxicosis; management of Graves' hyperthyroidism using radioactive iodine, antithyroid drugs, or surgery; management of toxic multinodular goiter or toxic adenoma using radioactive iodine or surgery; Graves' disease in children, adolescents, or pregnant patients; subclinical hyperthyroidism; hyperthyroidism in patients with Graves' ophthalmopathy; and management of other miscellaneous causes of thyrotoxicosis.

CONCLUSIONS

One hundred evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice.

Prediction of post-treatment hypothyroidism using changes in thyroid volume after radioactive iodine therapy in adolescent patients with Graves' disease

BACKGROUND

The goal of iodine-131 therapy for pediatric Graves' disease is to induce hypothyroidism. However, changes in post-treatment thyroid volume have not been investigated in pediatric and/or adolescent patients.

OBJECTIVE

The aim of this retrospective study was to examine whether changes in thyroid volume predict post-treatment hypothyroidism in adolescent Graves' disease patients.

PATIENTS AND METHODS

We used ultrasonography to examine changes in thyroid volume, and also assessed thyroid functions, at 0, 1, 3, 5, 8 and 12 months after iodine-131 treatment in 49 adolescents ranging in age from 12 to 19 years retrospectively. Based on thyroid function outcome at 12 months, patients were divided into two groups: 29 patients with overt hypothyroidism requiring levothyroxine replacement and 20 without overt hypothyroidism. We compared changes in post-radioiodine thyroid volume between the two groups.

RESULTS

About 90% of patients whose thyroid volume at 3 months after iodine-131 administration was less than 50% of the original volume were hypothyroid by one year after treatment (positive predictive value 88%, sensitivity 75.9%, specificity 85.0%).

CONCLUSIONS

We believe ultrasonographic measurement of thyroid volume at 3 months after iodine-131 to be clinically useful for predicting post-treatment hypothyroidism in adolescent Graves' disease patients.

Current concepts in graves' disease

Graves' disease is the most common cause of hyperthyroidism in the developed world. It is caused by an immune defect in genetically susceptible individuals in whom the production of unique antibodies results in thyroid hormone excess and glandular hyperplasia. When unrecognized, Graves' disease impacts negatively on quality of life and poses serious risks of psychosis, tachyarrhythmia and cardiac failure. Beyond the thyroid, Graves' disease has diverse soft-tissue effects that reflect its systemic autoimmune nature. Thyroid eye disease is the most common of these manifestations and is important to recognise given its risk to vision and potential to deteriorate in response to radioactive iodine ablation. In this review we discuss the investigation and management of Graves' disease, the recent controversy regarding the hepatotoxicity of propylthiouracil and the emergence of novel small-molecule thyroid-stimulating hormone (TSH) receptor ligands as potential targets in the treatment of Graves' disease.

Hyperthyroidism and other causes of thyrotoxicosis: management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists

BACKGROUND

Thyrotoxicosis has multiple etiologies, manifestations, and potential therapies. Appropriate treatment requires an accurate diagnosis and is influenced by coexisting medical conditions and patient preference. This article describes evidence-based clinical guidelines for the management of thyrotoxicosis that would be useful to generalist and subspeciality physicians and others providing care for patients with this condition.

METHODS

The development of these guidelines was commissioned by the American Thyroid Association in association with the American Association of Clinical Endocrinologists. The American Thyroid Association and American Association of Clinical Endocrinologists assembled a task force of expert clinicians who authored this report. The task force examined relevant literature using a systematic PubMed search supplemented with additional published materials. An evidence-based medicine approach that incorporated the knowledge and experience of the panel was used to develop the text and a series of specific recommendations. The strength of the recommendations and the quality of evidence supporting each was rated according to the approach recommended by the Grading of Recommendations, Assessment, Development, and Evaluation Group.

RESULTS

Clinical topics addressed include the initial evaluation and management of thyrotoxicosis; management of Graves' hyperthyroidism using radioactive iodine, antithyroid drugs, or surgery; management of toxic multinodular goiter or toxic adenoma using radioactive iodine or surgery; Graves' disease in children, adolescents, or pregnant patients; subclinical hyperthyroidism; hyperthyroidism in patients with Graves' ophthalmopathy; and management of other miscellaneous causes of thyrotoxicosis.

CONCLUSIONS

One hundred evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice.

[Graves' ophthalmopathy from the internist's perspective]

Graves' orbitopathy (GO) is the most frequently observed extrathyroidal manifestation of Graves' disease occurring in up to 40% of patients. Most patients with Graves' orbitopathy are tested positive for TSH receptor autoantibodies (TRAb), which are pathognomonic for Graves' disease and also play a central pathogenetic role in the development of GO. For the diagnosis of Graves' disease, symptoms of hyperthyroidism, low TSH and high fT3 and/or fT4 levels and positive TRAbs are typical. All patients with Graves' disease must be regularly examined for extrathyroidal manifestations, especially for Graves' orbitopathy. For hyperthyroidism, treatment with antithyroidal drugs, such as thiamazole or propylthiouracil is initiated to quickly restore euthyroidism, which also frequently leads to improvement of Graves' orbitopathy. Smoking cessation is also heavily mandated. In cases of relapse or ineffective antithyroidal treatment, radioiodine therapy or thyroid surgery is a further definitive therapeutic option to treat hyperthyroidism. The management of Graves' orbitopathy remains clinically challenging and demands involvement of a multidisciplinary team including endocrinologists, ophthalmologists, surgeons, radiotherapists and nuclear medicine specialists.

Propylthiouracil (PTU) Hepatoxicity in Children and Recommendations for Discontinuation of Use

Propylthiouracil (PTU) was introduced for clinical use in July 1947 for Graves' disease (GD) treatment. Over the 60 years that this medication has been used, reports of PTU-related liver failure and death have accumulated. On October 28, 2008, an expert panel evaluated PTU drug safety in children at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) It is estimated that about 4000 pediatric patients per year with GD are being treated with antithyroid drugs (ATDs) in the United States, and up to 30% of pediatric patients with GD are being treated with PTU. The risk of severe PTU-induced liver failure is estimated as 1 in 2000-4000 children. The number of children developing reversible PTU-induced liver injury is estimated to be at least 1 in 200. Routine biochemical surveillance of liver function and hepatocellular integrity is not useful in identifying children who will develop liver failure. Children appear to be at higher risk for PTU-induced liver injury than adults. PTU should not be used as first line therapy for the treatment of GD in children. Current PTU use in children taking this medication should be stopped in favor of alternate therapies.

An optimal treatment for pediatric Graves' disease is radioiodine

CONTEXT

Antithyroid medications, surgery, and radioactive iodine have been used for more than five decades for the treatment of hyperthyroidism due to Graves' disease in children, adolescents, and adults. Despite the widespread use of these different approaches, controversy still exists relative to the merits of each treatment, especially regarding the use of radioactive iodine.

OBJECTIVE

The objective of the study was to address the risk and benefits of (131)I therapy, as compared with other treatment approaches. POSITION: Long-term, spontaneous remission of Graves' disease occurs in less than 30% of children. Thus, the majority of children with Graves' disease will need definitive, curative therapy. There is little evidence that use of antithyroid medications beyond 1 or 2 yr increases the likelihood of spontaneous, long-term remission. Although the use of antithyroid medications is standard practice, the use of antithyroid medications involves definite risks. When used at sufficient doses, radioactive iodine is an effective cure for Graves' disease and is associated with few acute side effects. Potential long-term adverse side effects, including thyroid cancer and genetic damage, have yet to be observed in individuals treated as children or adolescents with (131)I.

CONCLUSION

Properly administered, radioactive iodine remains an ideal form of treatment for Graves' disease in the pediatric population. Because of the increased risk of thyroid cancer associated with low-dose thyroid irradiation in children, larger, rather than smaller, doses of (131)I should be given.

The treatment of Graves' disease in children

Graves' disease is the most common form of hyperthyroidism in childhood. Current treatment options include antithyroid medications, surgery, and radioactive iodine. Medical therapy is generally associated with long-term remission rates of less than 25% and a small risk of serious adverse reactions that include hepatic failure and bone marrow suppression. Total thyroidectomy is associated with very high cure rates and a small risk of hypoparathyroidism and recurrent laryngeal nerve damage. When radioactive iodine is used at appropriate doses, there is a very high cure rate without increased risks of thyroid cancer or genetic damage. Clinicians caring for the child or adolescent with Graves' disease are thus faced with using medications with potential short-term and long-term toxicity, for a condition in which spontaneous remission occurs in the minority of pediatric patients. Definitive therapy in the form of surgery or radioactive iodine is necessary and unavoidable for the majority of pediatric patients with Graves' disease.

Optimized radioiodine therapy for Graves?? disease: Two MIRD-based models for the computation of patient-specific therapeutic 131I activity

AIM

(131)I therapy is increasingly used for Graves' hyperthyroidism. Debate remains about the best method for calculating the activity to administer, as well as about the potential benefit of such computed activity. Several arguments plead, nevertheless, in favour of a personalized computation, such as inter-individual variations of thyroid volume and biokinetics.

METHODS

A MIRD-based dosimetric approach, with an additional extension that takes into account the variation of thyroid mass during the treatment, has been developed. This approach includes the benefits of a personalized determination of biokinetics. Results were compared with those of six methods widely used in routine practice. Forty-one patients were enrolled (34 women, seven men; mean age +/-SD: 48.11 +/- 6.4 years). (131)I uptakes were measured at 4, 24 and 96 h (36.2 +/- 14.6%, 42.8 +/- 9.7% and 27.6 +/- 6.8%, respectively), following administration of the tracer. The kinetics of iodine in the thyroid were evaluated using a two-compartment model (effective half-life of 5.1 +/- 1.6 days). Computations of activities to deliver the doses prescribed by the physician were done with the eight formalisms.

RESULTS

There was no statistical difference between results of the two MIRD-based formalisms (227 +/- 148 MBq and 213 +/- 124 MBq), which were also not significantly different from those obtained with the majority of the other methods (from 128 +/- 95 MBq to 275 +/- 223 MBq). However, a large intra-individual difference up to a factor of 2 between two given methods was found.

CONCLUSION

The formalism developed appears to be a good compromise between all the common formalisms already used in many institutions. Furthermore, it allows the exposures of target volumes and non-target volumes to be planned individually and practical individual radiation protection recommendations to be implemented.

A predictive mathematical model for the calculation of the final mass of Graves' disease thyroids treated with 131I

Substantial reductions in thyroid volume (up to 70-80%) after radioiodine therapy of Graves' hyperthyroidism are common and have been reported in the literature. A relationship between thyroid volume reduction and outcome of 131I therapy of Graves' disease has been reported by some authors. This important result could be used to decide individually the optimal radioiodine activity A0 (MBq) to administer to the patient, but a predictive model relating the change in gland volume to A0 is required. Recently, a mathematical model of thyroid mass reduction during the clearance phase (30-35 days) after 131I administration to patients with Graves' disease has been published and used as the basis for prescribing the therapeutic thyroid absorbed dose. It is well known that the thyroid volume reduction goes on until 1 year after therapy. In this paper, a mathematical model to predict the final mass of Graves' diseased thyroids submitted to 131I therapy is presented. This model represents a tentative explanation of what occurs macroscopically after the end of the clearance phase of radioiodine in the gland (the so-called second-order effects). It is shown that the final thyroid mass depends on its basal mass, on the radiation dose absorbed by the gland and on a constant value alpha typical of thyroid tissue. Alpha has been evaluated based on a set of measurements made in 15 reference patients affected by Graves' disease and submitted to 131I therapy. A predictive equation for the calculation of the final mass of thyroid is presented. It is based on macroscopic parameters measurable after a diagnostic 131I capsule administration (0.37-1.85 MBq), before giving the therapy. The final mass calculated using this equation is compared to the final mass of thyroid measured 1 year after therapy administration in 22 Graves' diseased patients. The final masses calculated and measured 1 year after therapy are in fairly good agreement (R = 0.81). The possibility, for the physician, to decide a therapeutic activity based on the desired decrease of thyroid mass instead of on a fixed thyroid absorbed dose could be a new opportunity to cure Graves' disease.

A dosimetric approach to patient-specific radioiodine treatment of Graves' disease with incorporation of treatment-induced changes in thyroid mass

The traditional algorithms (Marinelli-Quimby and MIRD) used for the absorbed dose calculation in radionuclide therapy generally assume that the mass of the target organs does not change with time. In radioiodine therapy for Graves' disease this approximation may not be valid. In this paper a mathematical model of thyroid mass reduction during the clearance phase (30-35 days) after 131I administration to patients with Graves' disease is presented. A new algorithm for the absorbed dose calculation is derived, taking into account the reduction of the mass of the gland resulting from the 131I therapy. It is demonstrated that thyroid mass reduction has a considerable effect on the calculated radiation dose. Either the model of the thyroid mass reduction or the new equation for the absorbed dose calculation depend on a parameter k for each patient. This parameter can be calculated after the administration of a diagnostic amount of radioiodine activity (0.37-1.85 MBq). Thus, thyroid absorbed dose and thyroid mass reduction during the first month after therapy can be predicted before therapy administration. The absorbed dose values calculated by the new algorithm are compared to those calculated by the traditional Marinelli-Quimby and MIRD algorithms.

Influence of iodine-131 dose on the outcome of hyperthyroidism in children

OBJECTIVES

Iodine-131 is an effective treatment for Graves' hyperthyroidism in children and adults. Yet the responses to treatment as related to iodine-131 dose in children are not well-defined. The objective of this study was to examine the relationship between the dose of iodine-131 in children with hyperthyroidism and thyroid status 1 year after treatment.

METHODS

We examined the outcome of iodine-131 treatment in children and adolescents with Graves' disease, as related to dose. Three iodine-131 doses were compared: 72 to 108 Gy (80-120 microCi/g), 180 to 225 Gy (200-250 microCi/g), and 270 to 364 Gy (300-405 microCi/g) in 31 patients ranging in age from 7 to 18 years old. Thyroid status was assessed >1 year after therapy.

RESULTS

We found that doses of 100 Gy (110 microCi/g), 200 Gy (220 microCi/g), and 300 Gy (330 microCi/g) resulted in hypothyroidism in 50%, 70%, and 95% of treated individuals, respectively. These data show that to insure ablation of thyroid tissue doses, >270 Gy (300 microCi/g) is needed, especially when the thyroid is large.

A theoretical model for prescription of the patient-specific therapeutic activity for radioiodine therapy of Graves' disease

A fundamental function of the thyroid is to extract iodine from the blood, synthesize it into thyroid hormones, and release it into the circulation under feedback control by pituitary-secreted hormones. This capability of the thyroid, termed as functionality, can in principle be related to the severity of hyperthyroidism in individual patients. In this paper the uptake and release of 131I by the thyroid following the administration of 131I therapy for Graves' disease has been theoretically studied. The kinetics of iodine in the thyroid and blood have been evaluated using a two-compartment model. This simplified model appears to be adequate for dosimetry purposes and allows one to correlate levels of increased thyroid functionality (hyperthyroidism) with clinically measurable kinetic parameters. An expression has been derived for the rate of change of thyroid mass following therapy; this has the same form as an empirical relationship described in an earlier work. A method is presented for calculation of the amount of radioiodine activity to be administered to individual patients in order to achieve the desired final functionality of the gland. The activity to be administered is based on measurements of 131I kinetics after the administration of a 'low-activity' (1850 kBq) tracer for treatment planning.

Tratamento do hipertireoidismo da Doença de Graves

A Doença de Graves constitui a forma mais comum de hipertireoidismo e três abordagens terapêuticas são atualmente utilizadas: drogas antitireoidianas (DAT), cirurgia e iodo radioativo (131I). As DAT continuam como tratamento de primeira escolha em pacientes com doença leve, bócios pequenos, crianças e adolescentes, e em situações especiais como na gravidez. Por outro lado, o 131I tem sido cada vez mais utilizado, porque é considerado um tratamento seguro, definitivo e de fácil aplicação. O risco de exacerbação do hipertireoidismo após administração do 131I, os fatores prognósticos de falência e o cálculo da dose administrada têm sido alguns dos aspectos discutidos na literatura recentemente, e são particulamente comentados nesta revisão. O tratamento cirúrgico constitui quase um tratamento de exceção, com indicação para os casos em que as terapias anteriores não possam ser utilizadas.

Influence of thyroid volume reduction on calculated dose in radioiodine therapy of Graves' hyperthyroidism

Administration of radioactive iodine (131I) is an effective treatment for hyperthyroidism due to Graves' disease. Recently several investigators have shown that the success of this therapy may depend on the absorbed dose to the thyroid. Thyroid dose varies inversely with the mass of the gland. Much experimental evidence demonstrates that a reduction of the thyroid volume (mass) may occur after radioiodine therapy. In this work we evaluate the influence of the volume reduction on the calculation of the absorbed dose to the thyroid. A mathematical model of thyroid mass reduction after 131I therapy is presented, based on masses evaluated with ultrasonography of ten patients treated in the endocrinology department of our hospital. This model was applied to the general formula for calculation of the thyroid doses in these patients. The dose values obtained considering a reduction of thyroid mass after the treatment are often quite different from those obtained without considering change in mass (from 9% to 30% greater). We conclude that the consideration of thyroid mass reduction is important for an accurate estimation of the calculated dose.

Radioiodine therapy in Graves' disease patients with large diffuse goiters treated with or without carbimazole at the time of radioiodine therapy

We sought to ascertain how high the success rates of radioiodine therapy are for Graves' disease patients with large diffuse goiters when aiming for a constant absorbed dose of 250 Gy. Thirty-six patients with a thyroid volume of 50-110 mL were evaluated for changes in thyroid function and appearance 3, 6, and 12 months after radioiodine therapy. Success was defined as definitive elimination of hyperthyroidism following therapy (hypothyroidism corrected with thyroxine on diagnosis); failure as persistent/recurrent hyperthyroidism after 12 months. Overall success rate was 50%. However, a subgroup of 20 patients without simultaneous carbimazole (carbimazole-off) showed a highly significantly larger success rate (85%) than the 16 patients with simultaneous carbimazole (carbimazole-on) at the time of radioiodine therapy (6.3%, p < 0.000005). Successful cases showed a significantly higher volume reduction after radioiodine than failures (75.5% vs. 35.4%, p < 0.00005). Stepwise logistic regression showed that therapy failure was related to administration of carbimazole during radioiodine therapy (p < 0.0250 and absorbed dose (p < 0.05), but not thyroid function (free triiodothyronine [FT3] and free thyroxine [FT4]), initial thyroid volume or thyrotropin-receptor antibody (TRAb) value. However, a significant correlation of therapy success to absorbed dose (r = 0.69, p < 0.005) could be shown only for carbimazole-off patients, but not for the others. Finally, multivariate factor analysis consistently showed that therapy success was correlated only to absorbed dose and antithyroid drugs, not to initial thyroid volume, TRAb value, or thyroid function. Thyroid volume per se is not responsible for the lower success rate in Graves' disease patients with large goiters because even a comparable group of 32 Graves' disease patients with small thyroid glands (< or =20 mL) and without simultaneous carbimazole showed a success rate of 87.5%. The high failure rate in the carbimazole-on patients (absorbed dose comparable to carbimazole-off) is due to the simultaneous administration of carbimazole. Therefore, if clinically feasible, we recommend discontinuing carbimazole at least one day before beginning radioiodine therapy.

Success rate of radioiodine therapy in Graves' disease: the influence of thyrostatic medication

There is controversy whether simultaneous thyrostatic medication influences the outcome of radioiodine (131I) therapy in Graves' disease by reducing the absorbed energy dose of 131I when delivering a standard dose. We therefore sought to ascertain whether the outcome of ablative 131I therapy is in any way affected by simultaneous thyrostasis (carbimazole) by aiming for a constant absorbed dose of 200-250 Gy. We prospectively studied 207 patients with Graves' disease (106 with and 101 without simultaneous carbimazole at the time of 131I therapy). All patients were reexamined 3, 6, and 12 months after 131I therapy. The 101 nonthyrostatic patients showed a highly significantly greater success rate (93%) than the 106 thyrostatic patients (49%). Stepwise logistic regression demonstrated that failure was related to the administration of carbimazole during 131I therapy (P < 0.00005) and the absorbed dose (P < 0.025), but was not related to free T3, free T4, TSH receptor antibodies, or thyroid volume. The success rate was 100% in 93 nonthyrostatic patients with absorbed doses of 200 Gy or more, but was only 12.5% (1 of 8) for absorbed doses less than 200 Gy. Correlation between success and absorbed dose was significantly higher for nonthyrostatic than for thyrostatic patients (r = 0.93 vs. r = 0.24). Sixteen patients who discontinued thyrostasis 1-3 days before 131I therapy showed 94% successes. Simultaneous thyrostasis is the decisive factor against a successful 131I therapy even if the significantly reduced 131I uptake/half-life values under thyrostasis are compensated with a higher delivered dose to ensure a comparable absorbed dose, possibly due to the additionally effective radioprotective properties of carbimazole. Therefore, if clinically feasible, we recommend discontinuing thyrostasis at least 1 day before beginning 131I therapy, because even in hyperthyroid nonthyrostatic patients the success rate was 100%.

Outcome of treatment of hyperthyroidism

This is a retrospective study designed to evaluate the initial response to carbimazole in patients with Graves' disease (GD), possible determinants of that response, the frequency of occurrence of adverse effects during treatment with carbimazole and the frequency of transient and permanent hypothyroidism after treatment with 131I in patients with GD and multinodular goiter (MNG). Data were collected from patients who first presented with GD or MNG at the Department of Endocrinology of the Royal Infirmary of Edinburgh between 1 January 1993 and 31 August 1996. Patients were divided into three groups: patients with GD treated with a daily dose of 40 mg carbimazole, patients with GD treated with a single dose of 400 MBq 1311, and patients with MNG treated with the same dose of 131I. Of the patients younger than 30 years, 50% remained biochemically hyperthyroid after 4-6 weeks of treatment with carbimazole, compared to 14% of patients over 30. Other determinants of the response to carbimazole expressed as the fall in thyroid hormone levels after 4-6 weeks were: pretreatment levels of FT4, T3, TRAb and the 4 h 131I uptake, patients with the higher levels responding significantly better to carbimazole. Adverse effects were reported in 11.5% of patients. Of the patients with GD treated with 1311, 62.6% became hypothyroid, transient hypothyroidism occurred in only 2.4% of these cases. The main predictors of development of hypothyroidism were positive titres of antithyroid peroxidase antibodies (AbTPO) and antithyroglobulin antibodies (AbTg), with positive predictive values of 79.5 and 91.6 respectively. None of the patients with MNG became hypothyroid after treatment with 131I, a response significantly different from patients with GD. In conclusion, GD younger patients might benefit from higher initial doses of carbimazole. In patients with positive titres of AbTPO and AbTg, lower doses of 1311 might prevent hypothyroidism. Transient hypothyroidism was underestimated in this study. No permanent thyroxin replacement therapy should be started within the first six months after 131I treatment.

Treatment of Graves' hyperthyroidism with radioiodine: results of a prospective randomized study

In this paper, we report the results of a randomized prospective study on radioiodine treatment in patients with Graves' hyperthyroidism. Complete data were obtained in group 1 from 98 patients 6 months after application of a standard activity of 15 mCi (555 MBq) of 131I and in group 2 from 107 patients who received a target dose of 100 Gy. In group 1, the overall success rate was 71%, but the results in the subgroups clearly were related inversely to the thyroid volume, ranging from 100% in patients with a thyroid volume < 15 mL to about 20% in those with a thyroid size of > 60 mL. In contrast, patients who received a target of 100 Gy showed very similar results, with success rates of about 40-50% in all but one subgroup. Only patients with a thyroid volume < 15 mL had a success rate of about 80%. But due to an incidental increase of uptake and/or effective half-time from the test to the therapy activity, this subgroup received a target dose of about 160 Gy. Additional calculation of the actual target dose in group 1 (standard activity) showed that, with a dose of 200 Gy, a success rate of 80% was obtained. Also, the thyroid volume reduction was related inversely to the target dose. Because the literature is abundant, only a restricted number of references are discussed that are either in agreement with our results or in sharp contrast to them. The reason for these discrepant results might be the difference in the scheme of pretreatment or the different alimentary iodine supply between, for example, Great Britain and the United States on the one hand and Germany on the the other hand.