Short review: novel concepts in the approach to patients with amiodarone-induced thyrotoxicosis

INTRODUCTION

Amiodarone-induced thyrotoxicosis is associated with high morbidity and mortality rates. The approach to this condition is widely variable across different medical specialists and even among expert endocrinologists. As a matter of fact, the approach to amiodarone-induced thyrotoxicosis has always been considered difficult, due to diagnostic uncertainties easily resulting in missteps, and therapeutic challenges easily resulting in unresponsiveness or slow-responsiveness to the administered drugs.

PURPOSE

Our purpose is to review novelties emerged during the last years about this condition, with the aim to provide novel insights on the diagnostic and therapeutic management of this challenging condition.

Thyroid Eye Disease: Epidemiology, Natural History, and Risk Factors

BACKGROUND

Thyroid eye disease (TED) is an autoimmune disorder of the orbit and the most frequent extrathyroidal manifestation of Graves' disease but it may rarely occur in euthyroid/hypothyroid patients with chronic autoimmune thyroiditis.

EPIDEMIOLOGY

TED is a relatively infrequent disorder, particularly in its severe forms. Men tend to have more severe TED at an older age. The prevalence of TED is lower than in the past among patients with recent onset Graves' hyperthyroidism, and moderate-to-severe forms requiring aggressive treatments are no more than 5% to 6% of all cases.

NATURAL HISTORY

After an initial inflammatory (active) phase and a plateau phase, TED stabilizes and eventually inactivates (inactive or burnt-out phase) after an estimated period of 18-24 months. Minimal-to-mild TED often remits spontaneously, but complete restitutio ad integrum almost never occurs when TED is more than mild.

RISK FACTORS

Several risk factors contribute to its development on a yet undefined genetic background. Cigarette smoking is the most important of them, but thyroid dysfunction (both hyper- and hypothyroidism), radioactive iodine therapy (if not accompanied by low-dose steroid prophylaxis), elevated thyrotropin receptor antibodies, and, probably, hypercholesterolemia represent relevant modifiable risk factors. Early diagnosis, control and removal of modifiable risk factors, and early treatment of mild forms of GO (local treatment and selenium) may effectively limit the risk of progression to more severe forms.

Regulatory T Cells in the Pathogenesis of Graves' Disease

Maintaining a delicate balance between the prompt immune response to pathogens and tolerance towards self-antigens and commensals is crucial for health. T regulatory (Treg) cells are pivotal in preserving self-tolerance, serving as negative regulators of inflammation through the secretion of anti-inflammatory cytokines, interleukin-2 neutralization, and direct suppression of effector T cells. Graves' disease (GD) is a thyroid-specific autoimmune disorder primarily attributed to the breakdown of tolerance to the thyroid-stimulating hormone receptor. Given the limitations of currently available GD treatments, identifying potential pathogenetic factors for pharmacological targeting is of paramount importance. Both functional impairment and frequency reduction of Tregs seem likely in GD pathogenesis. Genome-wide association studies in GD have identified polymorphisms of genes involved in Tregs' functions, such as CD25 (interleukin 2 receptor), and Forkhead box protein P3 (FOXP3). Clinical studies have reported both functional impairment and a reduction in Treg frequency or suppressive actions in GD, although their precise involvement remains a subject of debate. This review begins with an overview of Treg phenotype and functions, subsequently delves into the pathophysiology of GD and into the existing literature concerning the role of Tregs and the balance between Tregs and T helper 17 cells in GD, and finally explores the ongoing studies on target therapies for GD.

2021 Asia-Pacific Graves' Disease Consortium Survey of Clinical Practice Patterns in the Management of Graves' Disease

AIM

Although Graves' disease (GD) is common in endocrine practices worldwide, global differences in diagnosis and management remain. We sought to assess the current practices for GD in countries across Asia and the Pacific (APAC), and to compare these with previously published surveys from North America and Europe.

METHODS

A web-based survey on GD management was conducted on practicing clinicians. Responses from 542 clinicians were received and subsequently analysed and compared to outcomes from similar surveys from other regions.

RESULTS

A total of 542 respondents participated in the survey, 515 (95%) of whom completed all sections. Of these, 86% were medical specialists, 11% surgeons, and 3% nuclear medicine physicians. In addition to serum thyroid-stimulating hormone (TSH) and free thyroxine assays, most respondents would request TSH-receptor autoantibody (TRAb) measurement (68%) during initial work-up. Thyroid ultrasound is requested by about half of respondents (53%), while the use of nuclear medicine scans is limited. The preferred first-line treatment is anti-thyroid drug (ATD) therapy (79%) with methimazole (MMI) or carbimazole (CBZ), followed by radioiodine (RAI; 19%) and surgery (2%). In case of surgery, one-third of respondents would opt for a subtotal rather than a total thyroidectomy. In case of mild Graves orbitopathy (GO), ATDs (67%) remains the preferred treatment, but a larger proportion of clinicians prefer surgery (20%). For a patient with intention to conceive, the preferred treatment pattern remained unchanged, although propylthiouracil (PTU) became the preferred ATD-agent during the first trimester. In comparison to European and American practices, marked differences were noted in the relatively infrequent usage of nuclear medicine scans and the overall higher use of a ATDs and β-blockers and adjunctive ATD-treatment during RAI in the APAC-group.

CONCLUSION

Although regional differences regarding the diagnosis and management of GD are apparent in this first pan-Asia-Pacific survey, this study reveals the overall approach to the management of this disease in Asia-Pacific generally tends to fall between the trends appreciated in the American and European cohorts.

Immunomodulatory role of vitamin D and selenium supplementation in newly diagnosed Graves' disease patients during methimazole treatment

Introduction

Methimazole (MMI) represents the conventional therapeutic agent for Graves' disease (GD) hyperthyroidism, but MMI efficacy is limited since it marginally affects the underlying autoimmune process. In a previous study, we randomly assigned 42 newly diagnosed GD patients with insufficient vitamin D (VitD) and selenium (Se) levels to treatment with MMI alone (standard) or combined with selenomethionine and cholecalciferol (intervention) and observed a prompter resolution of hyperthyroidism in the intervention group.

Methods

In the present study, we aimed to explore changes in peripheral T regulatory (Treg) and circulating natural killer (NK) cell frequency, circulating NK cell subset distribution and function, during treatment.

Results

At baseline, circulating total CD3^-CD56⁺NK cells and CD56^bright NK cells were significantly higher in GD patients than in healthy controls (HC) (15.7 ± 9.6% vs 9.9 ± 5.6%, p=0.001; 12.2 ± 10.3% vs 7.3 ± 4.1%, p=0.02, respectively); no differences emerged in Treg cell frequency. Frequencies of total NK cells and CD56^bright NK cells expressing the activation marker CD69 were significantly higher in GD patients than in HC, while total NK cells and CD56^dim NK cells expressing CD161 (inhibitory receptor) were significantly lower. When co-cultured with the K562 target cell, NK cells from GD patients had a significantly lower degranulation ability compared to HC (p<0.001). Following 6 months of treatment, NK cells decreased in both the intervention and MMI-alone groups, but significantly more in the intervention group (total NK: -10.3%, CI 95% -15.8; -4.8% vs -3.6%, CI 95% -9; 1.8%, p=0.09 and CD56^bright NK cells: -6.5%, CI 95% -10.1; -3 vs -0.9%, CI 95% -4.4; 2%, p=0.03). Compared to baseline, CD69⁺ NK cells significantly decreased, while degranulation ability slightly improved, although no differences emerged between the two treatment groups. Compared to baseline, Treg cell frequency increased exclusively in the intervention group (+1.1%, CI 95% 0.4; 1.7%).

Discussion

This pilot study suggested that VitD and Se supplementation, in GD patients receiving MMI treatment, modulates Treg and NK cell frequency, favoring a more pronounced reduction of NK cells and the increase of Treg cells, compared to MMI alone. Even if further studies are needed, it is possible to speculate that this immunomodulatory action might have facilitated the prompter and better control of hyperthyroidism in the supplemented group observed in the previous study.

A potential role of human RNASET2 overexpression in the pathogenesis of Graves' disease

Genetic variation of the gene encoding for the only human enzyme of the T2 ribonucleases family (RNASET2) emerged in genome-wide association studies as a putative risk hotspot for Graves' disease (GD). T2 ribonucleases activities include immune regulation, induction of cell apoptosis and differentiation. Several reports supported the hypothesis that RNASET2 represents a "danger" message addressed to the innate immune system in peculiar conditions. This was a longitudinal, case-control study. RNASET2 protein levels were assessed in blood samples from 34 consecutive newly diagnosed GD patients and in healthy controls. At enrollment, RNASET2 levels were significantly higher in GD patients (98.5 ± 29.1 ng/ml) compared to healthy controls (72.5 ± 27.9 ng/ml, p = 0.001). After 6 months of methimazole treatment, RNASET2 levels significantly decrease and return to levels similar to healthy controls (62.4 ± 22 ng/ml, p = 0.69). These preliminary results suggest that RNASET2 is overexpressed in patients with GD and might represent an "alarm signal" generated by thyroid cells in response to endogenous or environmental stress to alert the immune system.

Real-life data on the impact of medical therapy for amiodarone-induced thyrotoxicosis on CV events and hospitalizations

CONTEXT

Patients with amiodarone-induced thyrotoxicosis (AIT) often receive the initial therapy for thyrotoxicosis in several different medical settings before admission to a referral center. Whether the first-line medical therapy (i.e. therapies for thyrotoxicosis at first diagnosis of AIT) affects the outcome of AIT patients is unknown.

STUDY DESIGN

Single-center historical-prospective cohort study of 313 AIT patients.

METHODS

Clinical and biochemical data were collected at first diagnosis, at a referral center, and during the course of AIT. Primary outcomes were cardiovascular events and hospitalizations. First-line therapies were considered appropriate when they included glucocorticoids for type 2 AIT and methimazole for type 1 AIT at the approved dosage, either alone (optimal medical therapy, OMT) or in combination (right-dose combination therapy, RCT). Other therapies were considered not appropriate, including no therapy. Duration of exposure to thyrotoxicosis was the time from first diagnosis of AIT to its remission.

RESULTS

34.5% patients received appropriate therapies (28.1% OMT, 6.4% RCT), whereas the remaining (65.5%) received non-appropriate therapies. Cardiovascular events, and hospitalizations were more frequent in patients who received non-appropriate therapies (33.2% vs 4.5%, and 24.9% vs 6.5%, respectively; p<0.0001 for both). Appropriate therapies reduced serum thyroid hormone concentrations (p=0.018) from first diagnosis to referral, unlike the non-appropriate therapies. The duration of exposure to thyrotoxicosis was longer in patients receiving non-appropriate therapies and was a risk factor for arrhythmias (HR 1.004, p=0.0008), MACEs (HR 1.004, p=0.020) and hospitalizations (HR 1.006, p<.0001).

CONCLUSIONS

The first medical therapy of AIT influences the exposure time to thyrotoxicosis and the occurrence of cardiovascular events and hospitalizations.

Current concepts regarding Graves' orbitopathy

Graves' orbitopathy (GO) is an orbital autoimmune disorder and the main extrathyroidal manifestation of Graves' disease, the most common cause of hyperthyroidism. GO affects about 30% of Graves' patients, although fewer than 10% have severe forms requiring immunosuppressive treatments. Management of GO requires a multidisciplinary approach. Medical therapies for active moderate-to-severe forms of GO (traditionally, high-dose glucocorticoids) often provide unsatisfactory results, and subsequently surgeries are often needed to cure residual manifestations. The aim of this review is to provide an updated overview of current concepts regarding the epidemiology, pathogenesis, assessment, and treatment of GO, and to present emerging targeted therapies and therapeutic perspectives. Original articles, clinical trials, systematic reviews, and meta-analyses from 1980 to 2021 were searched using the following terms: Graves' disease, Graves' orbitopathy, thyroid eye disease, glucocorticoids, orbital radiotherapy, rituximab, cyclosporine, azathioprine, teprotumumab, TSH-receptor antibody, smoking, hyperthyroidism, hypothyroidism, thyroidectomy, radioactive iodine, and antithyroid drugs. Recent studies suggest a secular trend toward a milder phenotype of GO. Standardized assessment at a thyroid eye clinic allows for a better general management plan. Treatment of active moderate-to-severe forms of GO still relies in most cases on high-dose systemic-mainly intravenous-glucocorticoids as monotherapy or in combination with other therapies-such as mycophenolate, cyclosporine, azathioprine, or orbital radiotherapy-but novel biological agents-including teprotumumab, rituximab, and tocilizumab-have achieved encouraging results.

Management of Graves' hyperthyroidism: present and future

INTRODUCTION

Graves' disease (GD) is an autoimmune disorder due to loss of tolerance to the thyrotropin receptor (TSHR) and ultimately caused by stimulatory TSHR antibodies (TSHR-Ab). GD may be associated with extrathyroidal manifestations, mainly Graves' orbitopathy. Treatment of GD relies on antithyroid drugs (ATDs), radioactive iodine (RAI), thyroidectomy. The major ATD limitation is the high recurrence rate after treatment. The major drawback of RAI and thyroidectomy is the inevitable development of permanent hypothyroidism.

AREAS COVERED

Original articles, clinical trials, systematic reviews, meta-analyses from 1980 to 2021 were searched using the following terms: Graves' disease, management of Graves' disease, antithyroid drugs, radioactive iodine, thyroidectomy, Graves' orbitopathy, thyroid-eye disease.

EXPERT OPINION

ATDs are the first-line treatment worldwide, are overall safe and usually given for 18-24 months, long-term treatment may decrease relapses. RAI is safe, although associated with a low risk of GO progression, particularly in smokers. Thyroidectomy requires skilled and high-volume surgeons. Patients play a central role in the choice of treatment within a shared decision-making process. Results from targeted therapies acting on different steps of the autoimmune process, including iscalimab, ATX-GD-59, rituximab, blocking TSHR-Ab, small molecules acting as antagonists of the TSHR, are preliminary or preclinical, but promising in medium-to-long perspective.

Add-On Effect of Selenium and Vitamin D Combined Supplementation in Early Control of Graves' Disease Hyperthyroidism During Methimazole Treatment

Prompt and stable control of hyperthyroidism is fundamental to avoid the detrimental effects of thyroid hormone excess, and antithyroid drugs, mainly methimazole (MMI), represent the first-line treatment for Graves' disease (GD) hyperthyroidism. Decreased serum concentrations of selenium (Se) and calcifediol (25(OH)D, VitD) have been reported in newly diagnosed GD patients in observational studies. Low Se levels might exacerbate oxidative stress by compromising the antioxidant machinery's response to reactive oxygen species, and low VitD levels might hamper the anti-inflammatory immune response. We performed a randomized controlled clinical trial (EudraCT 2017-00505011) to investigate whether Se and cholecalciferol (VitD) addition to MMI is associated with a prompter control of hyperthyroidism. Forty-two consecutive patients with newly-onset GD and marginal/insufficient Se and VitD levels were randomly assigned to treatment with either MMI monotherapy or MMI combined with Se and VitD. Se treatment was withdrawn after 180 days, while the other treatments were continued. Combination therapy resulted in a significantly greater reduction in serum FT4 concentration at 45 days (-37.9 pg/ml, CI 95%, -43.7 to -32.2 pg/ml) and 180 days (-36.5 pg/ml, CI 95%, -42 to -30.9 pg/ml) compared to MMI monotherapy (respectively: -25.7 pg/ml, CI 95%, -31.6 to -19.7 pg/ml and -22.9 pg/ml, CI 95%, -28 to -17.3 pg/ml, p 0.002). Data at 270 days confirmed this trend (-37.8 pg/ml, CI 95%, -43.6 to -32.1 pg/ml vs -24.4 pg/ml, CI 95%, -30.3 to -18.4 pg/ml). The quality of life (QoL) score was investigated by the validated "Thyroid-related Patient-Reported Outcome" questionnaire (ThyPRO). ThyPRO composite score showed a greater improvement in the intervention group at 45 days (-14.6, CI 95%, -18.8 to -10.4), 180 (-9, CI 95%, -13.9 to -4.2) and 270 days (-14.3, CI 95%, -19.5 to -9.1) compared to MMI group (respectively, -5.2, CI 95%, -9.5 to -1; -5.4, CI 95%, -10.6 to -0.2 and -3.5, CI 95%, -9 to -2.1, p 0-6 months and 6-9 months <0.05). Our results suggest that reaching optimal Se and VitD levels increases the early efficacy of MMI treatment when Se and VitD levels are suboptimal.

Identification of Two Different Phenotypes of Patients with Amiodarone-Induced Thyrotoxicosis and Positive Thyrotropin Receptor Antibody Tests

Introduction: Serum thyrotropin (TSH) receptor antibodies (TRAbs) are occasionally found in patients with amiodarone-induced thyrotoxicosis (AIT), and usually point to a diagnosis of type 1 AIT (AIT1) due to Graves' disease (GD). However, the TRAb role and function in AIT have not been clarified. Methods: A retrospective cohort study of 309 AIT patients followed at a single academic center over a 30-year period. AIT TRAb-positive patients (n = 21, 7% of all cases) constituted the study group; control groups consisted of type 2 AIT (AIT2) TRAb-negative patients (n = 233), and 100 non-AIT patients with GD. Clinical and biochemical data at diagnosis and during the course of disease were compared. Histological samples of patients who had total thyroidectomy were reviewed. Stored serum samples were used for a functional assay of TRAb class G immunoglobulins (IgGs) in Chinese hamster ovary (CHO) cells stably transfected with complementary DNA encoding for the TSH receptor. Results: TRAb-positive patients were grouped according to color flow Doppler sonography, radioactive iodine thyroid uptake, and duration of amiodarone therapy before thyrotoxicosis in type 1 (n = 9, 43%; TRAb1) or type 2 (n = 12, 57%; TRAb2) AIT. TRAb1 patients had clinical and biochemical features indistinguishable from GD controls, and were responsive to methimazole. Conversely, TRAb2 patients had clinical features similar to AIT2 controls, and were responsive to glucocorticoids, but not to methimazole. The CHO cell functional assay demonstrated that TRAb1 IgGs had a stimulatory effect on cyclic AMP production, which was absent in TRAb2 IgGs. Pathology in TRAb1 showed hyperplastic thyroid follicles and mild lymphocyte infiltration, reflecting thyroid stimulation. On the contrary, TRAb2 samples revealed follicle destruction, macrophage infiltration, and sometimes fibrosis, consistent with a destructive process. Conclusions: Almost 60% of TRAb-positive AIT patients had a destructive thyroiditis. TRAb-positive tests in AIT patients do thus not necessarily imply a diagnosis of GD and AIT1, and should be evaluated in the clinical and biochemical setting of each AIT patient and confirmed by measuring thyroid-stimulating immunoglobulins.

The 2021 European Group on Graves' orbitopathy (EUGOGO) clinical practice guidelines for the medical management of Graves' orbitopathy

Graves' orbitopathy (GO) is the main extrathyroidal manifestation of Graves' disease (GD). Choice of treatment should be based on the assessment of clinical activity and severity of GO. Early referral to specialized centers is fundamental for most patients with GO. Risk factors include smoking, thyroid dysfunction, high serum level of thyrotropin receptor antibodies, radioactive iodine (RAI) treatment, and hypercholesterolemia. In mild and active GO, control of risk factors, local treatments, and selenium (selenium-deficient areas) are usually sufficient; if RAI treatment is selected to manage GD, low-dose oral prednisone prophylaxis is needed, especially if risk factors coexist. For both active moderate-to-severe and sight-threatening GO, antithyroid drugs are preferred when managing Graves' hyperthyroidism. In moderate-to-severe and active GO i.v. glucocorticoids are more effective and better tolerated than oral glucocorticoids. Based on current evidence and efficacy/safety profile, costs and reimbursement, drug availability, long-term effectiveness, and patient choice after extensive counseling, a combination of i.v. methylprednisolone and mycophenolate sodium is recommended as first-line treatment. A cumulative dose of 4.5 g of i.v. methylprednisolone in 12 weekly infusions is the optimal regimen. Alternatively, higher cumulative doses not exceeding 8 g can be used as monotherapy in most severe cases and constant/inconstant diplopia. Second-line treatments for moderate-to-severe and active GO include (a) the second course of i.v. methylprednisolone (7.5 g) subsequent to careful ophthalmic and biochemical evaluation, (b) oral prednisone/prednisolone combined with either cyclosporine or azathioprine; (c) orbital radiotherapy combined with oral or i.v. glucocorticoids, (d) teprotumumab; (e) rituximab and (f) tocilizumab. Sight-threatening GO is treated with several high single doses of i.v. methylprednisolone per week and, if unresponsive, with urgent orbital decompression. Rehabilitative surgery (orbital decompression, squint, and eyelid surgery) is indicated for inactive residual GO manifestations.

Change in newly diagnosed Graves' disease phenotype between the twentieth and the twenty-first centuries: meta-analysis and meta-regression

PURPOSE

According to a few recent studies, the clinical phenotype of Graves' disease (GD) at onset is becoming milder in recent years, in terms of prevalence and severity of hyperthyroidism, goiter and overt eye disease. The aim of this study was to assess the change in GD phenotype across the late twentieth and the early twenty-first centuries.

MATERIALS AND METHODS

We carried out a systematic search of studies published between 1/1/1980 and 12/31/2017 describing naïve GD patients at diagnosis. We collected epidemiological, clinical, biochemical and serological data reported in the selected studies, and (1) conducted a single-arm meta-analysis to compare clinical and biochemical characteristics of naïve GD patients before and after year 2000 and (2) performed a meta-regression to identify the trend of the observed clinical presentations.

RESULTS

Eighty selected articles were related to the period before the year 2000, 30 to the years 2000-2017. According to demographics, the two defined populations were homogeneous at meta-analysis: overall estimated female prevalence was 81% [95% CI 79-82], mean estimated age of the entire population was 39.8 years [95% CI 38.4-41.1], with no significant differences between pre- and post-2000 groups (p > 0.05). The overall estimated prevalence of smokers was 40% [95% CI 33-46], with no significant difference between the two groups (p > 0.05). Mean estimated free thyroxine (FT4) and free triiodothyronine (FT3) levels at diagnosis were higher in the pre-2000 group: 4.7 ng/dl [95% CI 4.5-4.9] for FT4 and 14.2 pg/ml [95% CI 13.3-15.1] for FT3, as compared to the post-2000 group: 3.9 ng/dl [95% CI 3.6-4.2] for FT4 and 12.1 pg/ml [95% CI 11.0-13.3] for FT3 (all p < 0.01). Goiter estimated prevalence was higher in the pre-2000 group, 87% [95% CI 84-90], than in the post-2000 group, 56% [95% CI 45-67]. Estimated prevalence for Graves' Orbitopathy (GO) was 34% [95% CI 27-41] in the pre-2000 group and 25% [95% CI 19-30] in the post-2000 group (p = 0.03). Accordingly, meta-regression adjusted for covariates showed an average annual reduction of FT4 (- 0.040 ± 0.008 ng/dl, p < 0.0001), FT3 (- 0.316 ± 0.019 pg/ml, p < 0.0001), goiter prevalence (- 0.023 ± 0.008%, p = 0.006), and goiter size (- 0.560 ± 0.031 ml, p < 0.0001).

CONCLUSIONS

Our meta-analysis and meta-regression confirmed that GD phenotype at diagnosis is nowadays milder than in the past; we hypothesize that conceivable factors involved in this change are iodoprophylaxis, worldwide decrease in smoking habits, larger use of contraceptive pill and micronutrient supplementation, as well as earlier diagnosis and management.

Antithyroid drugs in Graves' hyperthyroidism: differences between "block and replace" and "titration" regimes in frequency of euthyroidism and Graves' orbitopathy during treatment

PURPOSE

Whereas antithyroid drugs (ATD) are the preferred treatment modality for Graves' hyperthyroidism (GH), there is still controversy about the optimal regimen for delivering ATD. To evaluate whether 'Block and Replace' (B + R) and 'Titration' (T) regimes are equivalent in terms of frequency of euthyroidism and Graves' Orbitopathy (GO) during ATD therapy.

METHODS

A prospective multicentre observational cohort study of 344 patients with GH but no GO at baseline. Patients were treated with ATD for 18 months according to B + R or T regimen in line with their institution's policy.

RESULTS

Baseline characteristics were similar in both groups. In the treatment period between 6 and 18 months thyrotropin (TSH) slightly increased in both groups, but TSH was on average 0.59 mU/L (95% CI 0.27-0.85) lower in the B + R group at all time points (p = 0.026). Serum free thyroxine (FT4) remained stable during the same interval, with a tendency to higher values in the B + R group. The point-prevalence of euthyroidism (TSH and FT4 within their reference ranges) increased with longer duration of ATD in both groups; it was always higher in the T group than in the B + R group: 48 and 24%, respectively, at 6 months, 81 and 58% at 12 months, and 87 and 63% at 18 months (p < 0.002). There were no significant differences between the B + R and T regimens with respect to the fall in thyrotropin binding inhibiting immunoglobulins (TBII) or thyroid peroxidase antibodies (TPO-Ab). GO developed in 15.9% of all patients: 9.1 and 17.8% in B + R group and T group, respectively, (p = 0.096). GO was mild in 13% and moderate-to-severe in 2%.

CONCLUSION

The prevalence of biochemical euthyroidism during treatment with antithyroid drugs is higher during T compared to B + R regimen. De novo development of GO did not differ significantly between the two regimens, although it tended to be higher in the T group. Whether one regimen is clinically more advantageous than the other remains unclear.