Effect of long-term continuous methimazole treatment of hyperthyroidism: comparison with radioiodine

Approach to the Patient Considering Long-term Antithyroid Drug Therapy for Graves' Disease

Antithyroid drugs (ATD) are the treatment of choice for the majority of patients with Graves' hyperthyroidism worldwide. However, relapse of hyperthyroidism after withdrawal of arbitrarily chosen conventional 12 to 18 months of therapy is very common. In the last 2 decades, many studies have shown that treatment with long-term ATD (LT-ATD) is effective and safe in the maintenance of euthyroidism. In addition, it has been reported that serum TSH receptor antibody may not decrease permanently before 5 to 6 years of ATD treatment, and clinical trials have shown that ≥5 years of ATD treatment is accompanied by remission in the majority of patients with Graves' hyperthyroidism. The objective of this article is to discuss the optimal time to withdraw of conventional ATD therapy, to illustrate the decision-making of the management of recurrent hyperthyroidism, to review the proper management of LT-ATD, and to generate suggestions for lifelong ATD treatment by discussing 4 scenarios of decision-making in patients with Graves' disease.

The Origin of Antithyroid Drugs

Background: When the antithyroid drugs were discovered in the early 1940s, they were immediately recognized as a revolutionary new treatment for hyperthyroidism. Although much has been learned about their mechanism of action and clinical utility, they continue to be used today in much the same way as they have been since their introduction. Summary: In 1995, Dr. Clark Sawin gave an address on the history of antithyroid drug development at the 11th International Thyroid Congress in Toronto, Ontario, Canada. In his review, Dr. Sawin recounted the original observations by Drs. Julia and Cosmo Mackenzie and Curt Richter at the Johns Hopkins University School of Medicine, and how their work ultimately led to Dr. Edwin (Ted) B. Astwood's seminal 1943 report on the use of thiourea and thiouracil in the Journal of the American Medical Association. He also described the development of propylthiouracil and methimazole as less toxic alternatives. He concluded his remarks by noting the often-serendipitous pathway of drug development and the role of pharmaceutical companies in the process. Conclusions: Antithyroid drugs remain a cornerstone of thyroid therapeutics. It is informative to review the process by which they came into use, as this is a seminal part of the history of thyroid disease in the 20th century. This knowledge may also spark additional research leading to new pharmacotherapies for patients with hyperthyroidism.

Prediction for recurrence following antithyroid drug therapy for Graves' hyperthyroidism

Objective

A common problem with antithyroid drugs (ATD) treatment in patients with Graves' disease (GD) is the high recurrence rate after drug withdrawal. Identifying risk factors for recurrence is crucial in clinical practice. We hereby prospectively analyze risk factors for the recurrence of GD in patients treated with ATD in southern China.

Subjects and methods

Patients who were newly diagnosed with GD and aged > 18 years were treated with ATD for 18 months and followed up for 1 year after ATD withdrawal. Recurrence of GD during follow-up was assessed. All data were analyzed by Cox regression with P values < 0.05 considered statistically significant.

Results

A total of 127 Graves' hyperthyroidism patients were included. During an average follow-up of 25.7 (standard deviation = 8.7) months, 55 (43%) had a recurrence within 1 year after withdraw of anti-thyroid drugs. After adjustment for potential confounding factors, the significant association remained for the presence of insomnia (hazard ratio (HR) 2.94, 95% confidence interval (CI) 1.47-5.88), greater goiter size (HR 3.34, 95% CI 1.11-10.07), higher thyrotrophin receptor antibody (TRAb) titer (HR 2.66, 95% CI 1.12-6.31) and a higher maintenance dose of methimazole (MMI) (HR 2.14, 95% CI 1.14-4.00).

Conclusion

Besides conventional risk factors (i.e., goiter size, TRAb and maintenance MMI dose) for recurrent GD after ATD withdraw, insomnia was associated with a 3-fold risk of recurrence. Further clinical trials investigating the beneficial effect of improving sleep quality on prognosis of GD are warranted.

Long-term thionamide antithyroid treatment of Graves' disease

Thionamide antithyroid drugs (ATD) are the treatment of choice for Graves' hyperthyroidism. The major drawback of ATD treatment for 1-2 years is the relapse of hyperthyroidism in about 50% of patients. Recently, it has been shown that ATD treatment for more than five years is accompanied by long-term remission in majority of patients without additional major side effects in both adults and children. Compared to radioactive iodine therapy, long-term ATD results in more favorable outcomes. This review summarizes the evidence on long-term ATD therapy regarding the remission rate of hyperthyroidism, efficacy and safety, indications and mode of therapy in patients with hyperthyroidism.

Approach to the Patient With a Suppressed TSH

Subclinical hyperthyroidism (SCH) is a laboratory diagnosis defined by a serum thyrotropin (TSH) concentration below the reference range (< 0.4 mU/L in most assays), and a free thyroxine (FT4) and 3,5,3'-triiodothyronine levels (FT3) in the reference range. Many patients diagnosed with SCH will be clinically euthyroid while others may present with manifestations characteristic of thyroid hormone excess, such as tachycardia, tremor, intolerance to heat, bone density loss, or weight loss. In addition to the laboratory abnormalities, patient factors such as age, symptoms, and underlying heart and bone disease are used to stratify patients for the risk of adverse outcomes and determine the appropriate treatment. Evaluation should include repeat thyroid function tests to document persistent TSH suppression, investigation of the underlying cause, as well as evaluation of the patient's risk of adverse outcomes in the setting of a subnormal TSH. Persistent SCH has been associated with an increased risk of a range of adverse events, including cardiovascular events such as atrial fibrillation and heart failure, bone loss and fracture, and in some studies, cognitive decline. Despite the consistent association of these adverse events with SCH, prospective studies showing improved outcomes with treatment remain limited. Management options include observation without active therapy, radioactive iodine ablation of the thyroid, antithyroid medication, thyroid surgery, or radiofrequency ablation, as appropriate for the patient and clinical setting. The choice of therapy should be guided by the underlying etiology of disease, patient factors, and the risks and benefits of each treatment option.

Long-term follow-up of Graves' orbitopathy after treatment with short-term or long-term methimazole or radioactive iodine

OBJECTIVE

The aim of this study was to compare long-term outcomes in terms of new onset or worsening of GO in patients with Graves' disease treated with different therapeutic modalities for hyperthyroidism.

METHODS

A total of 1163 patients with Graves' disease entered this study; 263 patients were treated with radioiodine and 808 patients received MMI therapy for a median of 18 months of whom, 178 patients continued MMI for a total of 96 months (long-term MMI). Thyroid hormonal status and GO were evaluated regularly for a median of 159 months since enrollment.

RESULTS

Rates of relapse, euthyroidism and hypothyroidism at the end of the follow-up were: radioiodine treatment: 16%, 22% and 62%, short-term MMI group: 59%, 36% and 5% and long-term MMI group: 18%, 80% and 2%, respectively. In the first 18 months of therapy, worsening of GO (11.5% vs 5.7%), and de novo development of GO (12.5% vs 9.8%) were significantly more frequent after radioiodine, p<0.004. The overall worsening and de novo development of GO from>18-234 months was 26(9.9%) in radioiodine and 8(4.5%) in LT-MMI groups, p<0.037. No case of worsening or new onset of GO was observed in patients treated with long-term MMI from>60-234 months of follow-up.

CONCLUSION

Progression and development of GO were associated more with radioiodine than MMI treatment; GO may appear de novo or worsen years after radioiodine but not after long-term MMI therapy.

Efficacy and Safety of Long-Term Methimazole versus Radioactive Iodine in the Treatment of Toxic Multinodular Goiter

BACKGRUOUND

This study compared the degree of sustained control of hyperthyroidism in patients with toxic multinodular goiter (TMNG) treated with long-term methimazole (LT-MMI) or radioactive iodine (RAI).

METHODS

In this clinical trial, 130 untreated patients with TMNG were randomized to either LT-MMI or RAI treatment. Both groups were followed for 108 to 148 months, with median follow-up durations of 120 and 132 months in the LT-MMI and RAI groups, respectively. Both groups of patients were followed every 1 to 3 months in the first year and every 6 months thereafter.

RESULTS

After excluding patients in whom the treatment modality was changed and those who were lost to follow-up, 53 patients in the LT-MMI group and 54 in the RAI group completed the study. At the end of the study period, 50 (96%) and 25 (46%) patients were euthyroid, and two (4%) and 25 (46%) were hypothyroid in LT-MMI and RAI groups, respectively. In the RAI group, four (8%) patients had subclinical hyperthyroidism. The mean time to euthyroidism was 4.3±1.3 months in LT-MMI patients and 16.3± 15.0 months in RAI recipients (P<0.001). Patients treated with LT-MMI spent 95.8%±5.9% of the 12-year study period in a euthyroid state, whereas this proportion was 72.4%±14.8% in the RAI-treated patients (P<0.001). No major treatment-related adverse events were observed in either group.

CONCLUSION

In patients with TMNG, LT-MMI therapy is superior to RAI treatment, as shown by the earlier achievement of euthyroidism and the longer duration of sustained normal serum thyrotropin.

Long-term management of Graves disease: a narrative review

Graves disease (GD) is the most common cause of hyperthyroidism, accounting for more than 90% of cases in Korea. Patients with GD are treated with any of the following: antithyroid drugs (ATDs), radioactive iodine (RAI) therapy, or thyroidectomy. Most patients begin treatment with ATDs, and clinical guidelines suggest that the appropriate treatment period is 12 to 18 months. While RAI treatment and surgery manage thyrotoxicosis by destroying or removing thyroid tissue, ATDs control thyrotoxicosis by inhibiting thyroid hormone synthesis and preserving the thyroid gland. Although ATDs efficiently control thyrotoxicosis symptoms, they do not correct the main etiology of GD; therefore, frequent relapses can follow. Recently, a large amount of data has been collected on long-term ATDs for GD, and low-dose methimazole (MMZ) is expected to be a good option for remission. For the long-term management of recurrent GD, it is important to induce remission by evaluating the patient's drug response, stopping ATDs at an appropriate time, and actively switching to surgery or RAI therapy, if indicated. Continuing drug treatment for an extended time is now encouraged in patients with a high possibility of remission with low-dose MMZ. It is also important to pay attention to the quality of life of the patients. This review aimed to summarize the appropriate treatment methods and timing of treatment transition in patients who relapsed several times while receiving treatment for GD.

Audit of long-term treatment outcomes of thyrotoxicosis in a single-centre virtual clinic: The utility of long-term antithyroid drugs

OBJECTIVE

To investigate the long-term outcomes and prognosis of thyrotoxicosis in a large number of patients in a single UK county (Leicestershire).

DESIGN

Retrospective cohort analysis of 56,741 thyroid function test (TFT) results, treatment modalities and outcomes in a well-established virtual thyrotoxicosis clinic database.

PATIENTS

One thousand four hundred and eighty-nine patients were included with a median length of follow-up of 10.9 years. The aetiology of thyrotoxicosis was autoimmune (85.9%), nodular (9.1%) and mixed (5.0%). Treatment modalities included antithyroid drugs (ATDs), radioiodine (RAI; 555 MBq fixed dose) and thyroidectomy.

METHODS

We analysed both individual TFTs and groups of sequential TFTs on or after the same thyroid treatment(s), which we describe as 'phase of thyroid care' (POTC). Patients studied entered the virtual clinic between 1 January 1995 and 1 January 2010; we exported data on every TFT sample up to April 2020.

RESULTS

ATD had been used in 99.2% (median 2, maximum seven courses) with long-term ATD (&gt;2 years) in 48%. RAI and thyroidectomy were used more commonly with nodular and mixed aetiology. Overall, T4 was more often controlled than thyroid-stimulating hormone (TSH), and at the latest follow-up, T4 was normal in &gt;96%, TSH in &gt;79% and both in &gt;76% of different aetiologies. The mean percentage control of T4 was 85% and TSH 50%; in long-term ATD courses, this improved to 89% and 62%, respectively. In the latest POTC, control of T4 and TSH was best in cases off treatment (95%/87%) and on T4 without ablative therapy (94%/72%), but was broadly similar in patients on long-term ATD (90%/68%), after RAI (92%/60%) or after thyroidectomy (91%/58%). After the first course of ATD, remission or hypothyroidism was seen in 47.3% autoimmune, 20.9% nodular and 32.5% mixed, with 90% relapses seen within 4 years. Relapse was more common in patients with ophthalmopathy, but there was no difference between the sexes.

CONCLUSIONS

Thyrotoxicosis can be well controlled with minimal specialist clinic attendance using a software-supported virtual shared-care scheme. Long-term ATD appears to be a valid patient choice achieving TFT control comparable to that seen after RAI or surgery. In patients with autoimmune disease, relapse is more common in patients with ophthalmopathy, and hypothyroidism is common after RAI. In nodular disease, we found that spontaneous remission may occur.

Treatment of post-radioactive iodine relapse of hyperthyroidism: comparison of long-term methimazole and radioactive iodine treatment

BACKGROUND

This study aimed to compare the time to achieve euthyroidism and sustained control of hyperthyroidism after treatment with radioactive iodine (RAI) or long-term methimazole (LT-MMI) in patients with post-RAI relapsed hyperthyroidism.

METHODS

Sixty four patients with recurrence of hyperthyroidism after RAI treatment were randomly assigned to either RAI or LT-MMI treatment. Both groups were followed every 1-3 months in the first year and then every 6 months for a total of 60 months.

RESULTS

In RAI and LT-MMI groups, mean age was 49.0 ± 12.1 and 50.1 ± 14.6 years and time of relapse of hyperthyroidism after previous RAI treatment was 23.2 ± 18.8 and 20.8 ± 17.1 months, respectively. At the end of study, in the LT-MMI group, 31 (97%) and 1 (3%) were euthyroid and hypothyroid, respectively; in the RAI group, 8 (25%) patients were euthyroid, whereas 18 (56%), 3 (9.5%) and 3 (9.5%) had overt hypothyroidism, subclinical hypothyroidism and hyperthyroidism, respectively. Mean time to euthyroidism was 9.4 ± 5.0 months in the RAI group and 3.5 ± 2.8 months in the LT-MMI group (p < 0.001). Patients in the RAI group spent 77.7 ± 14.0 percent and those in the LT-MMI group spent 95.2 ± 5.9 percent of 60 months in the euthyroid state (p < 0.001).

CONCLUSION

In patients with post-RAI relapse of hyperthyroidism, LT-MMI treatment was superior to radioiodine because of faster achievement of euthyroidism and more sustained control of hyperthyroidism during 60 months of follow-up.

2022 Update on Clinical Management of Graves Disease and Thyroid Eye Disease

The management of hyperthyroidism and extrathyroidal manifestations of Graves disease remains complex. Considerations that include patient preference, age, comorbidity, pregnancy, tobacco smoking, and social determinants of health must all be weaved into a cohesive management plan. A multidisciplinary team is required to manage all aspects of Graves disease, particularly thyroid eye disease, for which new therapeutic options are now available.

Appropriate duration of antithyroid drug treatment as a predictor for relapse of Graves' disease: a systematic scoping review

BACKGROUND

Following the conventional 12-18 month antithyroid drug (ATD) treatment in Graves' disease (GD), 50% of patients experience relapse of hyperthyroidism.

OBJECTIVE

The aim of this systematic scoping review was critical appraisal of duration of ATD therapy in the last 80 years.

METHODS

Articles were identified through the search of PubMed from January 1, 1941 to April 30, 2021. All study types were included. Articles were eligible if they reported data on the length of ATD treatment, particularly thyroid hormones and TSH receptor antibodies (TRAb) concentrations and specifically those with data on the remission and/or relapse rates.

RESULTS

We described major progress regarding the duration of ATD therapy and related outcomes at every 20 years. Articles of 1941-1960 were mainly concerned with determination of favorable treatment, minimal effective dose, side effects and rate of remission after < 12-month ATD therapy. Studies with larger number of patients and longer follow-ups appeared in 1961-1980; higher remission rate after 18-24 months versus 6 months of ATD therapy was reported. Articles of 1981-2000 focused on identification of factors associated with high relapse rates after discontinuation of ATD. In 2001-2021, ATD became the first choice of treatment in many countries. However, 12-18 months of ATD therapy was arbitrarily chosen as the appropriate option. According to recent studies, persistent normalization of TRAb occurs after 5 years of methimazole therapy and ATD treatment of > 60 months could offer a 4-year remission rate of 85%.

CONCLUSION

Long-term ATD treatment for more than 60 months is safe and effective, has the highest remission rate and cures most patients with GD; hence, it should be considered as the most appropriate duration for ATD therapy in these patients.

Cost-Effectiveness Analysis of Antithyroid Drug (Propylthiouracil) Compared to Radioactive Iodine for the Treatment of Graves’ Disease in Ethiopia

Background

Graves’ disease is an autoimmune disorder caused by stimulating antibodies. The peak incidence of Graves’ disease occurs among patients aged 30 to 60 years. Radioactive iodine (RAI) and antithyroid drug (ATD) have been well-established therapies for the treatment of Graves’ disease for several decades. However, there remain large variations in practice among physicians in the preferred modality and the method of administration.

Objective

To assess the cost-effectiveness of ATD (propylthiouracil) compared to RAI from a health care payer perspective in Ethiopia.

Methods

Markov model was constructed by using TreeAge software 2021 with different parameters, such as ATD, RAI, treatment failure, treatment success, hypothyroidism, and supplemental thyroxine to conduct a cost-effectiveness analysis. A hypothetical 40-year-old female patient with symptomatic Graves’ hyperthyroidism was simulated to estimate expected lifetime health outcomes, quality-adjusted life years (QALYs) and costs, discounted at 3%.

Results

RAI has lesser QALYs (14.19) and is less expensive (US$ 3583.22), while ATD has higher QALYs (16.54) and is more expensive (US$ 12531.68). The result showed that there was no dominant treatment option. The incremental cost-effectiveness ratio was US$ 3811.6 per QALY which was greater than one to three times the cost-effectiveness threshold of Ethiopia (US$ 783).

Conclusion

In this cost-effectiveness analysis, RAI was the preferred treatment strategy for Graves’ disease, since the cost needed to get one extra QALY through ATD was greater than one to three times the cost-effectiveness threshold of Ethiopia.

Benefits of Long-Term Continuation of Low-Dose Methimazole Therapy in the Prevention of Recurrent Hyperthyroidism in Graves' Hyperthyroid Patients: A Randomized Prospective Controlled Study

BACKGROUND

The long-term continuation of the low-dose antithyroid drug (ATD) beyond the standard duration of ATD therapy of 12-18 months to prevent recurrent hyperthyroidism (RH) is recommended with low quality of evidence.

OBJECTIVES

To examine whether long-term continuation of low-dose ATD beyond the recommended duration of treatment would provide a benefit in the prevention of RH in patients with Graves' hyperthyroidism (GH) who achieved euthyroid status with a standard course of ATD therapy.

METHODS

A 36-month prospective randomized controlled study was conducted in 184 patients who had first diagnosed GH and were treated with a standard regimen of ATD therapy using methimazole (MMI) until achieving euthyroidism that was stably maintained for at least 6 months with a low-dose of (2.5-5 mg/day) MMI. All patients had neither a history of adverse effects from MMI, recurrent GH, severe and active ophthalmopathy nor conditions known to affect thyroid function before randomization. The patients were randomized into 2 groups: one group (92 cases) was assigned to discontinue (DISCONT-MMI) and the other (92 cases) was assigned to continue low-dose MMI (CONT-MMI) that was taken at the time of enrollment. The patients in both groups were followed up at 3, 6, 12, 18, 24, 30, and 36 months. The rate of RH was compared between both groups, and the adverse effects and risk factors of RH were also studied.

RESULTS

At the end of the 36-month study, 83 cases in CONT-MMI and 90 cases in DISCONT-MMI were eligible for analysis. The cumulative rates of RH in CONT-MMI were significantly lower than those in DISCONT-MMI at every follow-up time point (1.2% vs. 11.2%, 6.8% vs. 18.4%, 11.0% vs. 27.2%, 11.0% vs. 35.0%, and 11.0% vs. 41.2% at 6, 12, 18, 24, and 36 months, respectively; p < 0.01). Cox proportional hazard multivariate analysis showed that there were 2 factors independently associated with the risk of RH, including continuation of low-dose MMI therapy, which decreased the risk of RH by 3.8 times (HR = 0.26, p = 0.007, 95% CI = 0.10-0.70) and age onset of hyperthyroidism before 40 years, which increased the risk of RH by 2.9 times (HR = 2.9, p = 0.015, 95% CI = 1.23-6.88). Neither minor nor major adverse effects of low-dose MMI therapy were observed during the study period.

CONCLUSIONS

In Graves' hyperthyroid patients with no or nonsevere ophthalmopathy who have completed a standard course of methimazole therapy without an adverse effect and have achieved an euthyroid status that is stably maintained with low-dose methimazole, a long-term continuation of the low-dose methimazole of 2.5-5 mg daily is effective and safe in the prevention of recurrent hyperthyroidism or maintenance of euthyroid status as long as the low-dose methimazole is continued. (TCTR20170705002).

Methimazole plus levothyroxine for treating hyperthyroidism in children: a systematic review and meta-analysis

BACKGROUND

Hyperthyroidism is a disease of excessive synthesis and secretion of thyroid hormones, and there is a lack of studies that have systematically evaluated the efficacy of the combination in treating hyperthyroidism. This study aimed to systematically evaluate the effectiveness and safety of methimazole combined with levothyroxine for treating hyperthyroidism in children.

METHODS

We searched PubMed, CNKI, Wanfang Database, EMBASE, Web of Science, and other online electronic databases to find correlation studies of methimazole combined with levothyroxine in treating hyperthyroidism in children from 2010 to 2021. Meta-analysis was performed using Stata 16 software.

RESULTS

Finally, 15 relevant articles were included comprising 1,718 pediatric patients. Meta-analysis results indicated that compared with methimazole alone (control group), the experimental group administered methimazole + levothyroxine had no evident difference in the level of thyroid-stimulating hormone [standardized mean difference (SMD) =-0.34, 95% confidence interval (CI): -1.02, 0.35, P=0.33], but notably improved the efficacy of clinical treatment of hyperthyroidism in children [odds ratio (OR) =5.77, 95% CI: 2.62, 12.74, P<0.001]. Meanwhile, the experimental group had lower adverse reaction rates (OR =0.28, 95%CI: 0.19, 0.40, P<0.001), free triiodothyronine (FT3) level (SMD =-0.85, 95% CI: -1.57, 0.13, P=0.02), free tetraiodothyronine (FT4) level (SMD =-0.94, 95% CI: -1.59, -0.30, P=0.004) and reduced thyroid volume (SMD =-1.3, 95% CI: -1.67, 0.93, P<0.001).

DISCUSSION

Using methimazole + levothyroxine to treat hyperthyroidism in children can raise the levels of FT3 and FT4, reduce the thyroid volume, improve clinical efficacy, and lower the adverse reaction rate of patients.

Long-term antithyroid drug therapy

PURPOSE OF REVIEW

Over the last 1-2 decades, patients and physicians have preferred antithyroid drug therapy as the initial treatment of Graves' disease, rather than radioactive iodine or surgery. More recently, the concept of long-term antithyroid drug therapy (LTADT; >24 months of treatment) has also become increasingly popular.

RECENT FINDINGS

Data from cohort studies and a prospective randomized trial suggest that LTATD therapy is safe and is associated with a higher chance of remission from Graves' disease than is shorter-term therapy. Also, LTADT may be associated with better quality of life and other clinical outcomes compared to radioiodine and surgery.

SUMMARY

Long-term antithyroid drug therapy is appropriate for children and young adults. This approach is a reasonable option in those who are doing well on a stable low dose of antithyroid drug therapy, and especially those who wish to avoid definitive treatment with radioactive iodine or surgery, given their inherent risks and need for lifelong hormonal replacement therapy.

Comparison of long-term antithyroid drugs versus radioactive iodine or surgery for Graves' disease: A review of the literature

BACKGROUND

The management of Graves' disease (GD) in the US is shifting towards increased use of anti-thyroid drugs (ATD). If patients fail to achieve remission after a standard course of therapy of 12-18 months, long-term treatment with ATD (≥24 months) may be chosen over definitive therapy with radioiodine (RAI) or surgery. Clinicians will need to contrast this strategy to ablative therapies as they help patients in decision making.

SUMMARY

Review of the literature illustrates that long-term ATD delivers euthyroidism with minimal complications, low financial cost and with an advantageous profile regarding quality of life (QoL) and other biological outcomes.

CONCLUSIONS

Long-term ATD is a viable alternative to ablative therapies in the management of GD offering advantages across multiple patient centred outcomes. Decision making must factor differences in this approach compared to ablative therapies and ultimately be tailored to individualized patient situations.

US-guided percutaneous microwave ablation for hyperthyroidism and immediate treatment response evaluation with contrast-enhanced ultrasound

Hyperthyroidism is a common disease mainly manifested by hyperexcitability of multiple systems and hypermetabolism. Currently, antithyroid drugs (ATDs), radioiodine therapy (RIT), and surgery are mainly used in the clinical treatment for primary hyperthyroidism. We reported a case of a 28-year-old female who received a novel treatment for primary hyperthyroidism. This patient had poor control of thyroid function while taking ATD, and her oral Methimazole (MMI) dose varied repeatedly between 20 mg qd and 15 mg qd, failing to maintain a stable status. To minimize the possible complication and to achieve drug reduction or withdrawal, she refused RIT and surgery and showed up in our department. The patient, diagnosed with Graves' disease (GD) and met the surgical indication after systematic clinical evaluation, was subject to ultrasound-guided percutaneous microwave ablation (MWA) of the partial thyroid gland with continuous oral administration of 20 mg qd MMI. The post-ablation condition was stable and the patient was discharged 2 days after the operation. Thyroid ultrasound and serum thyroid function test were examined regularly after ablation and the MMI dosage was gradually reduced according to the results of the biochemical examination. Five weeks after the operation, the patient completely discontinued the medication. Ultrasound-guided percutaneous microwave ablation is minimally invasive, safe, and effective, and has potential to be an alternative treatment besides the 3 classical treatments of hyperthyroidism.

Efficacy of low-dose methimazole in control of multiple relapses of Graves' hyperthyroidism: a case report

INTRODUCTION

Methimazole (MMI) is the treatment of choice for patients with Graves' disease. The major drawback of this treatment is the relapse of hyperthyroidism in half of the patients after discontinuation of the recommended conventional 12-18 months of MMI treatment. TSH receptor antibody (TRAb) concentration is recognized as the strongest predictor of hyperthyroidism relapse. In this case report, efficacy of low-dose MMI to control hyperthyroidism even after multiple recurrences in the setting of normal TRAb concentrations is shown.

CASE PRESENTATION

An 80-year-old Iranian woman with Graves' disease was treated with MMI for 31 years. While receiving treatment, she always had a normal serum TRAb concentration; however, three times during the 31 years she decided to stop MMI therapy, and each time the disease recurred 16-21 months after MMI withdrawal. It is noteworthy that she maintained euthyroidism with the low-dose 1.25-2.5 mg MMI daily without any adverse events during three decades of treatment.

CONCLUSIONS

Normal serum TRAb is not a sufficiently strong marker to predict relapse of Graves' hyperthyroidism. Long-term therapy with low-dose MMI is an effective and safe treatment to sustain euthyroidism.

Treatment of Subclinical Hyperthyroidism in the Elderly: Comparison of Radioiodine and Long-Term Methimazole Treatment

Background: This study aimed to compare the effectiveness and safety of radioiodine (RAI) and long-term methimazole (MMI) in the treatment of subclinical hyperthyroidism (SH) in the elderly. Methods: From 306 patients, aged ≥65 years, with SH, 83 patients with thyrotropin <0.1 mU/L entered the study. In this randomized parallel-group trial, 41 and 42 patients were randomized to either RAI or long-term MMI treatment, respectively. Results: In the RAI and MMI groups, 3 and 4 patients were excluded due to side effects, choosing other modes of treatment, and not returning for follow-up; 35 and 36 patients completed 60 months of follow-up, respectively. In the RAI group, 23 (66%) became hypothyroid, and 12 (34%) remained euthyroid 60 months after a fixed dose of 15 mCi RAI. In the MMI group, the starting dose was 10 mg daily and decreased to 4.9 ± 1.0, 4.3 ± 1.0, 4.4 ± 1.4, 4.3 ± 1.8, and 3.7 ± 1.3 mg after 1, 2, 3, 4, and 5 years of continuous MMI treatment, employing titration method. By the end of study, 34 (94%) patients were euthyroid and 2 patients with diffuse goiter developed spontaneous hypothyroidism with MMI treatment. Minor adverse events occurred in both groups in the first four months of treatment. No death or serious side effects were observed during 60 months of follow-up. Conclusions: Both RAI and long-term low-dose MMI therapies are effective and safe for treatment of SH in the elderly.

Control of Graves' hyperthyroidism with very long-term methimazole treatment: a clinical trial

BACKGROUND

Long-term antithyroid drug therapy has become one of the options for treatment of Graves' hyperthyroidism. The aim of this study was to compare thyroid status in those who discontinued methimazole (MMI) treatment after 12.8 years with those who continued MMI as long as 24 years.

METHODS

Fifty nine patients with Graves' disease on long-term MMI for 14.2 ± 2.9 years were recruited; 32 patients (54%) decided to discontinue MMI and 27 (46%) preferred additional years of MMI treatment. All patients were followed for a mean of 6 additional years.

RESULTS

Of 27 patients who continued MMI up to 24 years, suppressed serum thyrotropin (TSH) was not observed in any patient after the seventh year of treatment. Serum free thyroxine, triiodothyronine, TSH and TSH receptor antibody concentrations remained normal up to the length of the study. Mean daily dose of MMI to maintain TSH in the reference range decreased gradually and reached to 2.8 ± 1.7 mg by 24 years of MMI treatment. No adverse reaction related to MMI occured during additional years of therapy. In 32 patients who discontinued MMI, hyperthyroidism relapsed in 6 patients (19%), one left follow-up and 25 (78%) remained euthyroid during the study.

CONCLUSIONS

Long-term low dose MMI treatment may be a lifelong effective and safe therapeutic modality in patients with Graves' hyperthyroidism for prevention of relapse, if studies from other centers confirm findings of this research.

TRIAL REGISTRATION

IRCT201009224794N1, 2010-10-25. Retrospectively registered. https://www.irct.ir/trial/5143 .

Management of Graves Thyroidal and Extrathyroidal Disease: An Update

CONTEXT

Invited update on the management of systemic autoimmune Graves disease (GD) and associated Graves orbitopathy (GO).

EVIDENCE ACQUISITION

Guidelines, pertinent original articles, systemic reviews, and meta-analyses.

EVIDENCE SYNTHESIS

Thyrotropin receptor antibodies (TSH-R-Abs), foremost the stimulatory TSH-R-Abs, are a specific biomarker for GD. Their measurement assists in the differential diagnosis of hyperthyroidism and offers accurate and rapid diagnosis of GD. Thyroid ultrasound is a sensitive imaging tool for GD. Worldwide, thionamides are the favored treatment (12-18 months) of newly diagnosed GD, with methimazole (MMI) as the preferred drug. Patients with persistently high TSH-R-Abs and/or persistent hyperthyroidism at 18 months, or with a relapse after completing a course of MMI, can opt for a definitive therapy with radioactive iodine (RAI) or total thyroidectomy (TX). Continued long-term, low-dose MMI administration is a valuable and safe alternative. Patient choice, both at initial presentation of GD and at recurrence, should be emphasized. Propylthiouracil is preferred to MMI during the first trimester of pregnancy. TX is best performed by a high-volume thyroid surgeon. RAI should be avoided in GD patients with active GO, especially in smokers. Recently, a promising therapy with an anti-insulin-like growth factor-1 monoclonal antibody for patients with active/severe GO was approved by the Food and Drug Administration. COVID-19 infection is a risk factor for poorly controlled hyperthyroidism, which contributes to the infection-related mortality risk. If GO is not severe, systemic steroid treatment should be postponed during COVID-19 while local treatment and preventive measures are offered.

CONCLUSIONS

A clear trend towards serological diagnosis and medical treatment of GD has emerged.

Long-Term Treatment of Hyperthyroidism with Antithyroid Drugs: 35 Years of Personal Clinical Experience

Background: None of the current therapeutic approaches for management of Graves' disease has been able to re-establish normal thyroid function in all patients. Objective: To describe the author's 35 years of personal experience in the management of Graves' hyperthyroidism and, in doing so, review current articles published on the long-term medical treatment of hyperthyroidism. Methods: All published articles related to ≥4 years of continuous antithyroid drug (ATD) treatment were searched. Findings were added and compared with studies published by the authors on the same topic. Results: Long-term ATD treatment is effective and safe, both in children and adults, for treatment of hyperthyroidism. Treatment of Graves' patients with ATDs >60 months causes euthyroidism up to 4 years after discontinuation of ATDs in the majority of patients. Long-term ATD therapy is not inferior to radioiodine therapy and may sometimes even be superior in some aspects, when considering serum lipid profile, cardiac function, mood, and cognition. Conclusions: Long-term ATD therapy for Graves' hyperthyroidism is efficient and safe and induces control of hyperthyroidism, without rendering the patient hypothyroid in the majority of patients.

A Clinical Debate: What Is the Therapeutic Choice for Recurrent Graves' Hyperthyroidism?

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A New Perspective in the Management of Graves’ Hyperthyroidism

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Remission Rate of Graves' Disease and the Trend of Changes in Serum TSH Receptor Antibodies in Prolonged Antithyroid Drug Treatment

Context: Graves’ disease is an autoimmune disease caused by thyrotropin receptor antibodies (TRAb). These antibodies can be measured and used for the diagnosis, prediction of remission, and risk of Graves’ orbitopathy development. There are three treatments for Graves’ disease that have remained unchanged for the last 75 years: Antithyroid drugs, radioiodine, and surgery. Antithyroid drugs are the first treatment option worldwide and are usually used for 12 - 18 months. Recent reports suggest the use of antithyroid drugs for more than 18 months with better outcomes. This review focuses on two aspects of treatment with antithyroid drugs: The impact of using antithyroid drugs for more than 12 - 18 months on remission rates and the trend of TRAb during prolonged antithyroid drug treatment. Evidence Acquisition: A review was performed in Medline on the published work regarding the duration of ATD treatment and remission of Graves' disease and also ATD treatment and TRAb status during the 1990 - 2019 period. Results: Remission rates are variable (30% - 80%), and many clinical and genetic factors serve as predictors. The long-term use of antithyroid drugs appears to increase remission rates. TRAb values usually decline during ATD treatment, but the trend could occur in two ways: Becoming negative or showing a fluctuating pattern. However, approximately 10% of the patients will remain TRAb-positive after five years of treatment with antithyroid drugs. Conclusions: Antithyroid drugs can be used for long periods with an increase in remission rates, and a gradual decrease in TRAb levels, with the disappearance of TRAb in 90% of the patients after 60 months.

Patterns of Use, Efficacy, and Safety of Treatment Options for Patients with Graves' Disease: A Nationwide Population-Based Study

Background: Considerable uncertainty remains about the pattern of use of treatment options for Graves' disease (GD) and their comparative effectiveness and safety. Methods: Between 2005 and 2013, we identified patients with GD who received antithyroid drugs (ATDs), radioactive iodine (RAI) or surgery, and were represented in a large administrative data set in the United States (OptumLabs^® Data Warehouse). Results: We identified 4661 patients with GD: mean age 48 (SD ±14) years, white (63%), and female (80%). Patients received ATD, n = 2817 (60%), RAI, n = 1549 (33%), or surgery, n = 295 (6%). Success rates were 50% for ATD, 93% for RAI, and 99% for surgery. Median time to treatment failure was 6.8 months for ATD and 3 months for RAI and surgery. When patients were required to be on ATD for at least one year before assessing failure, the failure rate decreased to 25%. Adverse effects occurred in 12% of patients receiving ATD, 6% with RAI, and 24% with surgery. Factors associated with treatment success were age >55 years (for ATD) and female sex (for RAI). About 12% of patients receiving ATD continued this treatment for >24 months as initial therapy. When patients failed ATD therapy, the most common second-line therapy was reinitiation of ATD (65%), RAI (26%), and surgery (9%). Overall, 26% of patients remain on ATD therapy (combined first or second line). Conclusions: ATD therapy was the most common GD therapy and demonstrated the lowest efficacy and infrequent significant adverse effect profile. With one fourth of patients remaining on ATD treatment (initial or second modality treatment), it becomes imperative to determine the long-term efficacy, safety, costs, and burdens of this modality of treatment.

Hyperthyroidism

Hyperthyroidism is a condition where the thyroid gland produces and secretes inappropriately high amounts of thyroid hormone which can lead to thyrotoxicosis. The prevalence of hyperthyroidism in the United States is approximately 1.2%. There are many different causes of hyperthyroidism, and the most common causes include Graves' disease (GD), toxic multinodular goiter and toxic adenoma. The diagnosis can be made based on clinical findings and confirmed with biochemical tests and imaging techniques including ultrasound and radioactive iodine uptake scans. This condition impacts many different systems of the body including the integument, musculoskeletal, immune, ophthalmic, reproductive, gastrointestinal and cardiovascular systems. It is important to recognize common cardiovascular manifestations such as hypertension and tachycardia and to treat these patients with beta blockers. Early treatment of cardiovascular manifestations along with treatment of the hyperthyroidism can prevent significant cardiovascular events. Management options for hyperthyroidism include anti-thyroid medications, radioactive iodine, and surgery. Anti-thyroid medications are often used temporarily to treat thyrotoxicosis in preparation for more definitive treatment with radioactive iodine or surgery, but in select cases, patients can remain on antithyroid medications long-term. Radioactive iodine is a successful treatment for hyperthyroidism but should not be used in GD with ophthalmic manifestations. Recent studies have shown an increased concern for the development of secondary cancers as a result of radioactive iodine treatment. In the small percentage of patients who are not successfully treated with radioactive iodine, they can undergo re-treatment or surgery. Surgery includes a total thyroidectomy for GD and toxic multinodular goiters and a thyroid lobectomy for toxic adenomas. Surgery should be considered for those who have a concurrent cancer, in pregnancy, for compressive symptoms and in GD with ophthalmic manifestations. Surgery is cost effective with a high-volume surgeon. Preoperatively, patients should be on anti-thyroid medications to establish a euthyroid state and on beta blockers for any cardiovascular manifestations. Thyroid storm is a rare but life-threatening condition that can occur with thyrotoxicosis that must be treated with a multidisciplinary approach and ultimately, definitive treatment of the hyperthyroidism.

Safety of long-term antithyroid drug treatment? A systematic review

Continued low-dose MMI treatment for longer than 12-18 months may be considered in patients not in remission. However, ATDs are not free from adverse effects. We undertook a systematic review to clarify safety of long-term ATD treatment. Medline and the Cochrane Library for trials published between 1950 and Nov 2018 were systematically searched. We included original studies containing data for long-term (> 18 months) ATD treatment. Two reviewers independently extracted data from included trials and any disagreement was adjudicated by consensus. Of 615 related articles found, 12 fulfilled the criteria. Six articles had data for adults, five for non-adults and one article had data for both groups. The sample sizes ranged between 20 and 249 individuals, and the mean duration of ATD treatment ranged between 2.1 and 14.2 years. Considering all data from 1660 patients treated with ATD for a mean duration of 5.8 years (around 10,000 patient-years), major complications occurred only in 14 patients: 7 severe agranulocytosis, 5 severe liver damage, one ANCA-associated glomerulonephritis and one vasculitis with small cutaneous ulcerations. Minor complications rates were between 2 and 36%, while more complications were in higher doses and in the children. The most reported AE was cutaneous reaction; the other adverse events were elevated liver enzymes, leukocytopenia, arthritis, arthralgia, myalgia, thrombocytopenia, fever, nausea and oral aphthous. Long-term ATD treatment is safe, especially in low dose and in adults, indicating that it should be considered as an earnest alternative treatment for GD.

Increased Remission Rates After Long-Term Methimazole Therapy in Patients with Graves' Disease: Results of a Randomized Clinical Trial

Background: Studies differ regarding whether, compared with courses of conventional duration, longer-term antithyroid drug treatment increases frequency of remission in patients with Graves' hyperthyroidism. We prospectively conducted a randomized, parallel-group study comparing relapse rates in patients receiving longer-term versus conventional-length methimazole therapy. We also sought variables associated with relapse following the latter. Methods: We enrolled 302 consecutive patients with untreated first episodes of Graves' hyperthyroidism. After 18-24 months of methimazole, 258 patients (85.4%) were randomized to an additional 36-102-month courses ("long-term group": n = 130; scheduled total time on methimazole: 60-120 months) or discontinuation of methimazole ("conventional group": n = 128). Patients were followed 48 months postmethimazole cessation. We performed Cox proportional hazards modeling to identify factors associated with relapse after conventional courses. Results: Methimazole was given for 95 ± 22 months in long-term patients and 19 ± 3 months in the conventional group. Fourteen patients experienced cutaneous reactions and 2 liver enzyme elevations during the first 18 months of treatment; no further methimazole-related reactions were observed despite therapy for up to another 118 months. Hyperthyroidism recurred within 48 months postmethimazole withdrawal in 15% (18/119) of long-term patients versus 53% (65/123) of conventional group patients. In the conventional group, older age, higher triiodothyronine or thyrotropin receptor antibody concentrations, lower thyrotropin concentration, or possession of the rs1879877 CD28 polymorphism or the DQB1-05 HLA polymorphism were independently associated with relapse. Conclusion: Administration of low-dose methimazole for a total of 60-120 months safely and effectively treats Graves' hyperthyroidism, with much higher remission rates than those attained by using conventional 18-24-month courses.

When should antithyroid drug therapy to reduce the relapse rate of hyperthyroidism in Graves' disease be discontinued?

OBJECTIVE

The use of antithyroid drug (ATD) therapy in patients with Graves' disease (GD) hyperthyroidism has been increasing, but ATD therapy is associated with a higher relapse rate. We aimed to evaluate clinical factors for predicting relapse of GD after ATD therapy.

METHODS

Patients (n = 149) with newly diagnosed GD who achieved remission of hyperthyroidism after ATD therapy (≥6 months) were followed up for >18 months after ATD withdrawal. We evaluated the predictive factors of relapse during a median of 6.9 years of follow-up.

RESULTS

Disease relapse occurred in 52 patients (34.9%). By multivariate analyses, a duration of the minimum maintenance dose therapy (MMDT) of <6 months was a significant factor in disease relapse (hazard ratio [HR], 2.58; 95% confidence interval [CI], 1.47-4.52; p < 0.001), and a T3/free T4 (fT4) ratio > 120 at ATD withdrawal was significantly more frequent in patients with relapse (HR 2.43; 95% CI, 1.36-4.34; p = 0.002). In the prediction-of-relapse model, the likelihood of relapse was greater in the high-risk group, which had a short MMDT duration and a T3/fT4 ratio ≥120 (HR, 5.81; 95% CI, 2.52-13.39; p < 0.001) and the intermediate-risk group, which had a short MMDT duration or a T3/fT4 ratio < 120 (HR, 2.77; 95% CI, 1.26-6.13; p < 0.001), than in the low-risk group, which had a long MMDT duration and a T3/fT4 ratio < 120.

CONCLUSION

An MMDT longer than 6 months and a high T3/fT4 ratio at ATD withdrawal were independent predictors of relapse in patients who achieved initial remission after ATD for GD. These factors could be used to determine the optimal time to withdraw ATD during the treatment of GD hyperthyroidism.

The long-term follow-up of patients with thionamide-treated Graves' hyperthyroidism

Since there have been few reports on the long-term prognosis of Graves' hyperthyroidism, the prognosis of 549 Graves' hyperthyroidism patients initially treated with thionamide and followed for >8 (range: 8.6-36.4) years was studied, evaluating the change in the TSH binding inhibitor immunoglobulin activity (TBII). The distribution of the time required for the first disappearance of TBII was normal after logarithmic conversion, and the mean ± 2 SD was 1.5 (0.3-8.1) years. TBII became negative once within 5 years in 78.9% of patients. However, TBII re-elevation was observed in 47.8% of this group (fluctuating type). Remission was observed in 88.9% of the non-fluctuating type (smooth remission) and 37.2% of the fluctuating type patients. TBII remained positive for >5 years in 21.1% (smoldering type) of patients, with remission observed in only 19.8% of patients. Final remission was observed in 301 (54.8%) patients; the median time to remission was 6.8 (interquartile range: 4.0-10.9) years. A longer time until normalization of TBII and higher final thyroid weight were associated with a poor prognosis. Spontaneous hypothyroidism was observed in 6.0% of patients, independent of the TBII change. Our findings suggest that remission of Graves' hyperthyroidism mostly occurred after 4-11 years treatment. While predicting the prognosis before therapy was difficult, the clinical course may suggest a better prognosis if TBII disappears within five years without TBII fluctuation or enlargement of the goiter. Patients may safely wait more than five years to undergo ablative therapy if they hope to avoid permanent hypothyroidism.

Long-term Methimazole Therapy in Juvenile Graves' Disease: A Randomized Trial

BACKGROUND AND OBJECTIVES

Recent studies show that long-term (LT) antithyroid drugs reduce relapse of hyperthyroidism in patients with Graves' disease. Our objective was to evaluate the effectiveness and safety of LT methimazole treatment and to compare remission rates in Graves' disease patients after LT and short-term (ST) therapy.

METHODS

In this randomized, parallel group trial, 66 consecutive patients with untreated juvenile Graves' hyperthyroidism were enrolled. After a median 22 months of methimazole treatment, 56 patients were randomly assigned to either continue low-dose methimazole treatment (n = 24, LT group) or to discontinue treatment (n = 24, ST group). Twenty-four patients in LT group completed 96 to 120 months of methimazole treatment. Patients in both groups were managed for 48 months after discontinuation of treatment.

RESULTS

Except for 3 cases of cutaneous reactions, no other adverse events were observed throughout 120 months of methimazole therapy. Serum free thyroxine, triiodothyronine, thyrotropin, and thyrotropin receptor antibody remained normal, and the required daily dosage of methimazole was gradually decreased from 5.17 ± 1.05 mg at 22 months to 3.5 ± 1.3 mg between 96 and 120 months of treatment (P < .001). Hyperthyroidism was cured in 92% and 88% of LT patients and in 46% and 33% of ST patients, 1 and 4 years after methimazole withdrawal, respectively.

CONCLUSIONS

LT methimazole treatment of 96 to 120 months is safe and effective for treatment of juvenile Graves' disease. The four-year cure rate of hyperthyroidism with LT methimazole treatment is almost 3 times more than that of ST methimazole treatment.

Treatment of Toxic Multinodular Goiter: Comparison of Radioiodine and Long-Term Methimazole Treatment

Background: This study aimed to compare the effectiveness and safety of long-term methimazole (MMI) and radioiodine (RAI) in the treatment of toxic multinodular goiter (TMNG). Methods: In this randomized, parallel-group trial, 130 consecutive and untreated patients with TMNG, aged <60 years, were enrolled and randomized to either long-term MMI or RAI treatment. Both groups of patients were followed for 60-100 months, with median durations of 72 and 84 months in the MMI and RAI groups, respectively. Results: In the MMI and RAI groups, 12 and 11 patients, respectively, were excluded because of side effects, choosing other modes of treatment and not returning for follow-up; 53 and 54 patients, respectively, completed the study for 60-100 months. In the MMI group, two patients (3.8%) experienced subclinical hypothyroidism, and 51 (96.2%) remained euthyroid until the end of study. The dosage of MMI to maintain euthyroidism was 6.3 ± 2.0, 4.5 ± 0.9, and 4.1 ± 1.0 mg daily during the first, third, and fifth years of continuous MMI treatment. One patient had elevated liver enzymes, and three developed skin reactions during the first three months, but no adverse effects from MMI occurred from 4 to 100 months of therapy. In the RAI group, 22 (41%) became hypothyroid, 12 (22%) had persistence or recurrence of hyperthyroidism, and 20 (37%) became euthyroid after 16.7 ± 2.7 mCi ¹³¹I. Conclusion: Long-term, low-dose MMI treatment for 60-100 months is a safe and effective method for treatment of TMNG, and is not inferior to RAI treatment.

Pituitary-testicular Axis Dysfunction in Methimazole-induced Hypothyroidism in Rats

Introduction

Thyroid hormones play a major role in the regulation of testicular maturation and growth and in the control of Sertoli and Leydig cell functions in adulthood. When naturally occurring, hypothyroidism causes male hypogonadotropic hypogonadism and Sertoli cell function disorders, but when iatrogenic and methimazole-induced its influence on the pituitary-testicular axis function with respect to Sertoli cells is poorly known.

Material and Methods

Male adult Wistar rats (n = 14) were divided into two groups: E – taking methimazole orally for 60 days, and C – control animals. After 60 d, the concentrations in serum of testosterone, follicle-stimulating and luteinising hormones, and inhibins A and B were measured. Testicles were examined morphologically: the apoptotic Sertoli cell percentage (ASC%) and number of these cells functional per tubular mm² (FSCN/Tmm²) were calculated.

Results

In group E, inhibin A was higher while inhibin B was lower than in group C. ASC% was higher and FSCN/Tmm² lower in group E than in group C.

Conclusion

A specific modulation of Sertoli cell function in the course of methimazole-induced hypothyroidism leads to a simultaneous concentration increase in inhibin A and decrease in B. Inhibin A might share responsibility for pituitary-testicular axis dysfunction and hypogonadotropic hypogonadism in this model of hypothyroidism.

Effects of a rat model of gestational hypothyroidism on forebrain dopaminergic, GABAergic, and serotonergic systems and related behaviors

We investigated the effects of maternal hypothyroidism on forebrain dopaminergic, GABAergic, and serotonergic systems and related behavior in adult rat offspring. Experimental gestational hypothyroidism (EGH) was induced by administering 0.02% methimazole (MMI) to pregnant rats from gestational day 9 to delivery. Neurotransmitter-related protein and gene expression were evaluated in offspring forebrain at postnatal day (P) 120. Exploratory behavior, contextual fear conditioning, locomotion, and 30-day reserpine Parkinson induction were assessed from P75-P120. Protein and gene expression assessments of medial prefrontal cortex showed group differences in dopaminergic, GABAergic, and serotonergic receptors, catabolic enzymes, and transporters. Striatum of MMI offspring showed an isolated decrease in the dopaminergic enzyme, tyrosine hydroxylase. MMI exposure increased GABA and dopamine receptor expression in amygdala. MMI offspring also had decreased state anxiety and poor contextual fear conditioning. We found that baseline locomotion was not changed, but reserpine treatment significantly reduced locomotion only in MMI offspring. Our results indicated that restriction of maternal thyroid hormones reduced dopaminergic, GABAergic, and serotoninergic forebrain components in offspring. Tyrosine hydroxylase deficiency in the striatum may underlie enhanced reserpine induction of Parkinson-like movement in these same offspring. Deficits across different neurotransmitter systems in medial prefrontal cortex and amygdala may underlie decreased state anxiety-like behavior and reduced fear conditioning in offspring, but no changes in trait anxiety-like behavior occurred with maternal MMI exposure. These findings strongly support the hypothesis that adequate delivery of maternal thyroid hormones to the fetus is crucial to the development of the central nervous system critical for emotion and motor regulation.

Graves' Disease: Can It Be Cured?

Whether or not Graves' hyperthyroidism can be really cured, depends on the definition of "cure." If eradication of thyroid hormone excess suffices for the label "cure," then all patients can be cured because total thyroidectomy or high doses of ¹³¹I will abolish hyperthyroidism albeit at the expense of creating another disease (hypothyroidism) requiring lifelong medication with levothyroxine. I would not call this a "cure," which I would like to define as a state with stable thyroid stimulating hormone (TSH), free thyroxine, and triiodothyronine serum concentrations in the normal range in the absence of any thyroid medication. Surgery and radioiodine are unlikely to result in so-defined cures, as their preferable aim as stated in guidelines is to cause permanent hypothyroidism. Discontinuation of antithyroid drugs is followed by 50% recurrences within 4 years; before starting therapy the risk of recurrences can be estimated with the Graves' Recurrent Events After Therapy (GREAT) score. At 20-year follow-up about 62% had developed recurrent hyperthyroidism, 8% had subclinical hypothyroidism, and 3% overt hypothyroidism related to TSH receptor blocking antibodies and thyroid peroxidase antibodies. Only 27% was in remission, and might be considered cured. If the definition of "cure" would also include the disappearance of thyroid antibodies in serum, the proportion of cured patients would become even lower.

Antithyroid Drugs

The thionamide drugs, i.e. carbimazole and its metabolite methimazole (MMI), and propylthiouracil (PTU) have extensively been used in the management of various forms of hyperthyroidism over the past eight decades. This review aims to summarize different aspects of these outstanding medications. Thionamides have shown their own acceptable efficacy and even safety profiles in treatment of hyperthyroidism, especially GD in both children and adults and also during pregnancy and lactation. Of the antithyroid drugs (ATDs) available, MMI is the preferred choice in most situations taking into account its better efficacy and less adverse effects accompanied by once-daily dose prescription because of a long half-life and similar cost. Considering the more severe teratogenic effects of MMI, PTU would be the selected ATD for treatment of hyperthyroidism during pre-pregnancy months and the first 16 weeks of gestation. Recent studies have confirmed the efficacy and safety of long-term MMI therapy with low maintenance doses for GD and toxic multinodular goiter. Despite the long-term history of ATD use, there is still ongoing debate regarding their pharmacology and diverse mechanisms of action, viz. their immunomodulatory effects, and mechanisms and susceptibility factors to their adverse reactions.

Elastographic and Morphological Testicular Changes in Hypothyroidism - An Experimental Study

Introduction

Methimazole-induced hypothyroidism is a clinical problem in the treatment of hyperthyroidism in people and animals and is an example of metabolic disease that can lead to fertility disorders and can give elastographic testicular changes.

Material and Methods

Ultrasound elastography using the Esaote MyLab Twice ultrasound system and a morphological examination of testes were performed in seven methimazole-administered (group E) and seven healthy rats (group C).

Results

The elasticity ratio of strains in the scrotal wall of the near-field test area to testicular tissue (ELX-T-RAT) and hardness percentage of strained tissues in the defined area of a testicle (ELX-T%HRD) in group E were statistically significantly lower than in group C. The degree of spermatogenesis was statistically significantly higher in group E than in group C and similarly seminiferous tubule diameters in group E were statistically significantly higher than in group C. Body weight and testicular weight in group E were statistically significantly lower than in group C.

Conclusion

Changes in the elastographical parameters of testes may result from disorders secondary to hypothyroidism. The usefulness of elastography is noteworthy in the case of evaluation of testis function in patients with some metabolic disorders.

ANNIVERSARY REVIEW: Antithyroid drug therapy: 70 years later

The thionamide antithyroid drugs were discovered in large part following serendipitous observations by a number of investigators in the 1940s who found that sulfhydryl-containing compounds were goitrogenic in animals. This prompted Prof. Edwin B Astwood to pioneer the use of these compounds to treat hyperthyroidism in the early 1940s and to develop the more potent and less toxic drugs that are used today. Despite their simple molecular structure and ease of use, many uncertainties remain, including their mechanism(s) of action, clinical role, optimal use in pregnancy and the prediction and prevention of rare but potentially life-threatening adverse reactions. In this review, we summarize the history of the development of these drugs and outline their current role in the clinical management of patients with hyperthyroidism.

Treatment of adult Graves' disease

Treatment strategy in Graves' disease firstly requires recovery of euthyroid status by antithyroid therapy. Treatment modalities, precautions, advantages and side-effects are to be discussed with the patient. No particular treatment modality has demonstrated superiority. Pregnancy or pregnancy project affects choice of treatment and monitoring. Graves' orbitopathy is liable to be aggravated by iodine-131 treatment and requires pre-treatment assessment. Iodine-131 treatment aims at achieving hypothyroidism. Thyroid surgery for Graves' disease should preferably be performed by an expert team. In case of recurrence of hyperthyroidism, the various treatment options should be discussed with the patient. Empiric treatment of thyroid dermopathy uses local corticosteroids in occlusive dressing.

2018 European Thyroid Association Guideline for the Management of Graves' Hyperthyroidism

Graves' disease (GD) is a systemic autoimmune disorder characterized by the infiltration of thyroid antigen-specific T cells into thyroid-stimulating hormone receptor (TSH-R)-expressing tissues. Stimulatory autoantibodies (Ab) in GD activate the TSH-R leading to thyroid hyperplasia and unregulated thyroid hormone production and secretion. Diagnosis of GD is straightforward in a patient with biochemically confirmed thyrotoxicosis, positive TSH-R-Ab, a hypervascular and hypoechoic thyroid gland (ultrasound), and associated orbitopathy. In GD, measurement of TSH-R-Ab is recommended for an accurate diagnosis/differential diagnosis, prior to stopping antithyroid drug (ATD) treatment and during pregnancy. Graves' hyperthyroidism is treated by decreasing thyroid hormone synthesis with the use of ATD, or by reducing the amount of thyroid tissue with radioactive iodine (RAI) treatment or total thyroidectomy. Patients with newly diagnosed Graves' hyperthyroidism are usually medically treated for 12-18 months with methimazole (MMI) as the preferred drug. In children with GD, a 24- to 36-month course of MMI is recommended. Patients with persistently high TSH-R-Ab at 12-18 months can continue MMI treatment, repeating the TSH-R-Ab measurement after an additional 12 months, or opt for therapy with RAI or thyroidectomy. Women treated with MMI should be switched to propylthiouracil when planning pregnancy and during the first trimester of pregnancy. If a patient relapses after completing a course of ATD, definitive treatment is recommended; however, continued long-term low-dose MMI can be considered. Thyroidectomy should be performed by an experienced high-volume thyroid surgeon. RAI is contraindicated in Graves' patients with active/severe orbitopathy, and steroid prophylaxis is warranted in Graves' patients with mild/active orbitopathy receiving RAI.

Secondary and tertiary preventions of thyroid disease

INTRODUCTION

Secondary and tertiary preventions are concerned with the recognition of the disease process in a very early stage and delay in progression to complete disease and minimization of complications and the impact of illness.

METHODS

All articles related to secondary and tertiary prevention of thyroid diseases were reviewed. Using related key words, articles published between 2001 and 2015 were evaluated, categorized, and analyzed.

RESULTS

In secondary prevention, congenital hypothyroidism and subclinical hypo and hyperthyroidism are equally important. Routine screening of patients with multinodular goiter by either ultrasonography or calcitonin is a controversial issue, while calcitonin assessments in medullary cancer and RET in family members are recommended. Screening of thyroid disease in pregnancy is limited to those with risk factors. Views regarding the importance of thyroid autoimmunity in secondary prevention are also presented. In tertiary prevention, prescribing excessive doses of levothyroxine, in the elderly in particular and appropriate care of all patients to avoid progression and complications are the key issues.

CONCLUSION

Optimization of management of thyroid diseases requires timely screening, prevention of progression to more sever disease, optimal medical care, and avoidance of iatrogenic conditions.

Management of thyrotoxicosis in children and adolescents: 35 years' experience in 304 patients

BACKGROUND

Diffuse toxic goiter accounts for about 15% of all childhood thyroid diseases. There is great controversy over the management of Graves' disease in children and adolescents. This article reports our experience in 304 children and juvenile patients with Graves' disease.

METHODS

Between 1981 and 2015, 304 patients aged 5-19 years with diffuse toxic goiter were studied, of whom 296 patients were treated with antithyroid drugs (ATD) for 18 months. Patients with persistent or relapsed hyperthyroidism who refused ablative therapy with surgery or radioiodine were managed with continuous methimazole (MMI) treatment.

RESULTS

In 304 patients (245 females and 59 males), the mean age was 15.6±2.6 years. After 18 months of ATD therapy, 37 remained in remission and of the 128 who relapsed, two, 29 and 97 patients chose surgery, continuous ATD and radioiodine therapy, respectively. Of the 136 patients who received radioiodine, 66.2% became hypothyroid. Twenty-nine patients received continuous ATD therapy for 5.7±2.4 years. The mean MMI dose was 4.6±12 mg daily, no serious complications occurred and all of them remained euthyroid during the follow-up. Less abnormal thyroid-stimulating hormone (TSH) values were observed in these patients, as compared to patients who were on a maintenance dose of levothyroxine after radioiodine induced hypothyroidism.

CONCLUSIONS

Original treatment with ATD and subsequent radioiodine therapy remain the mainstay of treatment for juvenile hyperthyroidism. Continuous ATD administration may be considered as another treatment modality for hyperthyroidism.

Long-Term Antithyroid Drug Treatment: A Systematic Review and Meta-Analysis

BACKGROUND

Several studies have reported inconsistent findings on the advantages and disadvantages of long-term treatment with antithyroid drugs (ATD). A systematic review and meta-analysis was undertaken to clarify the numerous aspects of long-term treatment with ATD.

METHODS

Medline and the Cochrane Library for trials published between 1950 and May 2016 were systematically searched. Studies containing data for long-term (>24 months) ATD treatment were included. Summary estimates of pooled prevalence, odds ratio, and weighted mean difference were calculated with a random effects model.

RESULTS

Of 587 related articles found, six fulfilled the inclusion criteria. Long-term ATD treatment induced a remission rate of 57% [confidence interval (CI) 45-68%], a rate that was higher in adults than in non-adults (61% vs. 53%). The rate of complications was 19.1% [CI 9.6-30.9%], of which only 1.5% were major complications. The annual remission rate for each year of treatment was 16% [CI 10-27%], which was higher in adults than non-adults (19% vs. 14%). However, it should be noted that this is not a true linear correlation, but a positive relationship can be suggested between time and remission rate. Meta-regression revealed that smoking had a significant lowering effect on remission rate.

CONCLUSIONS

Long-term ATD treatment is effective and safe, especially in adults, indicating that it should be considered as an alternative treatment for Graves' disease.

Effect of Antithyroid Therapies on Bone and Body Composition: A Prospective, Randomized, Clinical Study Comparing Antithyroid Drugs with Radioiodine Therapy

BACKGROUND

Thyrotoxicosis is associated with loss of body weight and bone mineral content (BMC). Antithyroid drugs (ATD) and radioiodine therapy (RIT) are the common options for the management of thyrotoxicosis. We evaluated the effect of ATD and RIT on BMC and body composition.

MATERIALS AND METHODS

In this prospective study, we randomized 60 patients of thyrotoxicosis (20-50 years, treatment naïve, males) to receive either ATD (Group 1) using carbimazole or RIT (Group 2). We excluded patients with significant ophthalmopathy and thyroid malignancy. The patients were followed serially for 1 year. Body composition was analyzed using the bioimpedance method and BMC by dual-energy X-ray absorptiometry technique. The data were analyzed using appropriate statistical measures.

RESULTS

The patients had a mean age of 33 ± 4.2 years and mean symptoms duration of 8.2 ± 2.7 months before the diagnosis. A total of 51 patients had Graves' disease, and the remaining 9 had toxic multinodular goiter. BMC at lumbar spine and femoral neck improved with both the therapies similarly at the end of 1 year. The body weight, protein, and fat content also increased after 1 year of observation similar between the two groups. None of the observed parameters showed a difference with regard to the mode of ATD.

CONCLUSION

ATD and RIT have comparable effects on the bone and body composition in the management of thyrotoxicosis. Further long-term studies are needed to confirm the observed findings.