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Amiodarone, a bi-iodinated benzofuran derivative, is among the most commonly used antiarrhythmic drugs due to its high level of effectiveness. Though initially categorized as a class III agent, amiodarone exhibits antiarrhythmic properties across all four classes of antiarrhythmic drugs. Amiodarone is highly effective in maintaining sinus rhythm in patients with paroxysmal atrial fibrillation while also playing a crucial role in preventing a range of ventricular arrhythmias. Amiodarone has a complex pharmacokinetic profile, characterized by a large volume of distribution and a long half-life, which can range from several weeks to months, resulting in prolonged effects even after discontinuation. Side effects may include thyroid dysfunction, pulmonary fibrosis, and hepatic injury, necessitating regular follow-ups. Additionally, amiodarone interacts with several drugs, including anticoagulants, which must be managed to prevent adverse effects. Therefore, a deep understanding of both oral and intravenous formulations, as well as proper dosage adjustments, is essential. The aim of this paper is to provide a comprehensive and updated review on amiodarone's indications, contraindications, recommended dosages, drug interactions, side effects, and monitoring protocols. [ABSTRACT FROM AUTHOR]

Atrial fibrillation is the most common heart rhythm disorder in patients with chronic heart failure. One of the most effective antiarrhythmic drugs for the treatment and prevention of a wide range of supraventricular and ventricular tachyarrhythmia is amiodarone. In the group of patients with paroxysmal atrial fibrillation and low left ventricular ejection fraction, it is the drug of choice when conducting a „rhythm control“ strategy. Patients receiving amiodarone often develop an adverse event – amiodarone-induced thyrotoxicosis, which exacerbates the course of cardiovascular pathology. In this article, we consider a clinical case of amiodarone-induced thyrotoxicosis in a 30-year-old patient with dilated cardiomyopathy and agranulocytosis that developed against the background of thyrostatic therapy.

Background: Amiodarone-induced thyrotoxicosis (AIT) may pose treatment challenges. We present a series of patients in which we achieved the normalisation of free T3 (FT3) using intravenous methylprednisolone (ivMP) in AIT refractory to thiamazole and oral prednisone. Namely, in three males (aged 56, 50 and 64, all with a history of AF and/or a low ejection fraction), an addition of ivMP resulted in the normalisation of FT3, which allowed successful thyroidectomy. In another case of a 65-year-old man, we initially succeeded in the normalisation of FT3 using ivMP from FT4 > 7.77 ng/dL (0.93–1.7) to 2.41 ng/dL and in that of FT3 from 14.95 pg/mL (2–4.4) to 2.05 pg/mL), but four weeks after stopping ivMP, despite the continuation of thiamazole and prednisone, there was rebound thyrotoxicosis: FT4 > 7.77 ng/dL and FT3—5.46 pg/mL. Intravenous MP was restated leading to a decline in FT4 to 2.51 ng/dL and in FT3 to 1.92 pg/mL, thus allowing a successful thyroidectomy. Finally, in a 78-year-old man with AF, goitre, and AIT resistant to thiamazole, prednisone and lithium carbonate, we obtained a reduction in FT4 to 1.51 ng/dL and in FT3 to 3.17 pg/mL after seven pulses of ivMP. Oral prednisone was gradually reduced and successfully stopped about six months later. He remained on low-dose thiamazole (5 mg od). Conclusions: Pulse ivMP in addition to oral steroids may be a useful adjunct therapy either for the preparation of a thyroidectomy or as a treatment modality in drug-resistant AIT. Though a total cure is possible, there is a danger of a rebound worsening of thyrotoxicosis after premature discontinuation of ivMP. [ABSTRACT FROM AUTHOR]

Context: Patients with amiodarone-induced thyrotoxicosis (AIT) often receive initial therapy for thyrotoxicosis in several different medical settings before admission to a referral center. Objective: This work aimed to determine whether first-line medical therapy (ie, therapies for thyrotoxicosis at first diagnosis of AIT) affects the outcome of AIT patients. Methods: A single-center historical-prospective cohort study was conducted on 313 AIT patients. Clinical and biochemical data were collected at first diagnosis, at a referral center, and during the course of AIT. Primary outcomes were cardiovascular (CV) 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 dose, 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: A total of 34.5% patients received appropriate therapies (28.1% OMT, 6.4% RCT), whereas the remaining (65.5%) received inappropriate therapies. CV events and hospitalizations were more frequent in patients who received inappropriate therapies (33.2% vs 4.5%, and 24.9% vs 6.5%, respectively; P<.0001 for both). Appropriate therapies reduced serum thyroid hormone concentrations (P=.018) from first diagnosis to referral, unlike the inappropriate therapies. The duration of exposure to thyrotoxicosis was longer in patients receiving inappropriate therapies and was a risk factor for arrhythmias (hazard ratio [HR] 1.004; P=.0008), major acute CV events (HR 1.004; P= .020), and hospitalizations (HR 1.006; P<.0001). Conclusion: The first medical therapy of AIT influences the exposure time to thyrotoxicosis and the occurrence of CV events and hospitalizations. [ABSTRACT FROM AUTHOR]

The OBJECTIVE of the study was to analyze the experience of performing thyroidectomy (TE) in patients with amiodarone-induced thyrotoxicosis (AmIT) at our centre.METHODS AND MATERIALS. The study included 12 patients with AmIT who underwent TE. Medical records were analyzed to assess the features of the AmIT and indications for TE. We also studied the operation protocols and postoperative follow-up data. Intraoperative, early and long-term postoperative complications were recorded. The long-term TE results were evaluated by the dynamics of the left ventricular ejection fraction (LVEF) based on the echocardiography data.RESULTS. The main indications for TE included the resistance of thyrotoxicosis to medication and worsening of the cardiac pathology. No cases of thyrotoxicosis progression or thyrotoxic crisis were registered during the operation. The vocal cord paresis developed in one case, completely restored in a year. Blood loss was minimal in all cases. Other intraoperative complications were absent. Not a single death was registered in the early postoperative period. At this period, a short paroxysm of atrial fibrillation resolved on its own was registered in patient with arrhythmogenic right ventricular dysplasia. A patient with biventricular chronic heart failure of a high functional class died 39 days after the operation due to a massive pulmonary thromboembolism. The long-term results of TE were evaluated in eight patients. In four out of five patients with initially reduced LVEF, it increased. In three patients with initially normal LVEF, it did not change.CONCLUSION. Thyroidectomy is an effective and safe treatment in patients with AmIT, including those with the persistent thyrotoxicosis and severe cardiac pathology. The success is possible when the preparation of patients for the intervention is carried out by a team of specialists experienced in treating of such patients.

A 60-year female with no preceding thyroid disease presented in August 2020 with severe debilitating progressive motor weakness of her lower limbs. Initial investigations revealed an acute myopathy secondary to thyrotoxicosis. On further review it was noted that the patient had ceased amiodarone treatment for rhythm control of atrial fibrillation and associated tachyarrhythmia-induced cardiomyopathy 10 days prior to admission to hospital. The patient was treated with high dose carbimazole and prednisone with marked improvement in mobility over the next 2 weeks. Her weekly thyroid function tests continued to ameliorate with progressive improvement in her mobility and return to functional baseline over a two-month period.

Amiodarone is commonly used nowadays for the treatment of atrial fibrillation (AF). The wide use of this medication has led to the occurrence of adverse events, including pulmonary toxicity, hepatotoxicity, thyroid dysfunction, and many others. Higher doses of Amiodarone of ≥400 mg/day have been linked to increased complications. We present a case of a 70-year-old male with multivessel coronary artery disease (CAD) with ischemic cardiomyopathy and severe peripheral artery disease (PAD) who underwent an elective left femoral to posterior tibial bypass surgery followed by percutaneous coronary intervention (PCI) complicated by new-onset AF. The patient was loaded with 150 mg of intravenous (IV) Amiodarone followed by 360 mg infusion over six hours for chemical cardioversion. The patient was then maintained on oral Amiodarone 400 mg/day until the day of presentation when he complained of progressive dyspnea. Imaging was significant for diffuse ground glass opacities and interstitial thickening. The echocardiogram revealed an improved ejection fraction (EF) of 40% from 20%. The patient had worsening oxygenation despite adequate IV diuresis and developed severe acute respiratory distress syndrome (ARDS) requiring mechanical ventilation (MV). A bronchoscopy with bronchoalveolar lavage (BAL) showed diffuse alveolar hemorrhage (DAH) with a high lymphocyte count and negative infectious disease testing. Lab tests revealed elevated liver enzyme levels. There were also changes in thyroid function from baseline with elevated free T4 at 1.83 ng/dL (0.8-1.4 ng/dL), suppressed thyroid stimulating hormone (TSH) at 0.109 mIU/mL (0.4-4 mIU/mL), negative anti-thyroglobulin (TG) antibodies, and anti-thyroid peroxidase (TPO) antibodies indicating a type 2 Amiodarone-induced thyrotoxicosis. Unfortunately, the patient's condition deteriorated further despite appropriate treatment, and it was ultimately followed by his demise. Severe, fatal cases of Amiodarone toxicity are scarce, but more reports are being seen. We strongly believe clinicians should have a high index of suspicion for Amiodarone-related adverse events in elderly males with cardiopulmonary comorbidities. It is imperative to have an increased understanding, greater vigilance, and closer monitoring of pulmonary function tests (PFTs), laboratory tests, and imaging studies., Competing Interests: Human subjects: All authors have confirmed that this study did not involve human participants or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Al-Hiari et al.)

Context: Patients with amiodarone-induced thyrotoxicosis (AIT) and severely reduced left ventricular ejection fraction (LVEF) have a high mortality rate that may be reduced by total thyroidectomy. Whether in this subset of patients thyroidectomy should be performed early during thyrotoxicosis or later after restoration of euthyroidism has not yet been settled.Objectives: Mortality rates, including peritreatment mortality and 5-year cardiovascular mortality, and predictors of death, evaluated by Cox regression analysis.Methods: Retrospective cohort study of 64 consecutive patients with AIT selected for total thyroidectomy from 1997 to 2019. Four groups of patients were identified according to serum thyroid hormone concentrations and LVEF: Group 1 (thyrotoxic, LVEF <40%), Group 2 (thyrotoxic, LVEF ≥40%), Group 3 (euthyroid, LVEF < 40%), Group 4 (euthyroid, LVEF ≥40%).Results: Among patients with low LVEF (Groups 1 and 3), mortality was higher in patients undergoing thyroidectomy after restoration of euthyroidism (Group 3) than in those submitted to surgery when still thyrotoxic (Group 1): peritreatment mortality rates were 40% versus 0%, respectively (P = .048), whereas 5-year cardiovascular mortality rates were 53.3% versus 12.3%, respectively (P = .081). Exposure to thyrotoxicosis was longer in Group 3 than in Group 1 (112 days, interquartile range [IQR] 82.5-140, vs 76 days, IQR 24.8-88.5, P = .021). Survival did not differ in patients with LVEF ≥40% submitted to thyroidectomy irrespective of being thyrotoxic (Group 2) or euthyroid (Group 4): in this setting, peritreatment mortality rates were 6.3% versus 4% (P = .741) and 5-year cardiovascular mortality rates were 12.5% and 20% (P = .685), respectively. Age (hazard ratio [HR] 1.104, P = .029) and duration of exposure to thyrotoxicosis (HR 1.004, P = .039), but not presurgical serum thyroid hormone concentrations (P = .577 for free thyroxine, P = .217 for free triiodothyronine), were independent predictors of death.Conclusions: A prolonged exposure to thyrotoxicosis resulted in increased mortality in patients with reduced LVEF, which may be reduced by early thyroidectomy. [ABSTRACT FROM AUTHOR]

The review presents recent data on the pathogenesis, diagnosis and treatment of amiodarone-induced thyrotoxicosis (AIT), which is a frequent complication of amiodarone (Am) therapy. Changes in secretion and metabolism of thyroid hormones are described under the influence of short-term and long-term therapy. The development of AIT leads to worsening of arrhythmias, aggravation of circulatory insufficiency, deterioration of the patients condition. Two types of AIT are distinguished, as well as mixed form. Diagnostic criteria of AIT type 1 and AIT type 2 are described. The most informative test for differential diagnosis between first and second types of AIT and mixed forms is ultrasound examination of the thyroid gland with Doppler blood flow evaluation and radionuclide scanning with 99 mTc-sestaMIBI. Medical management is determined by the type of AIT, the state of cardiovascular system and the risk of recurrent arrhythmias. Pharmacological management of AIT depends on its type and comprises the use of anti-thyroid medications or glucocorticoids. The possibility of continuing antiarrhythmic amiodarone therapy in patients who underwent AIT is discussed. In patients with AIT type 1 and mixed form drug cancellation is required, if this is not possible radical treatment of thyrotoxicosis (radioiodine therapy, thyroidectomy) is applied. AIT type 2 is a self-limiting process with life-threatening arrhythmias, and amiodarone therapy can be continued. The effectiveness of radioiodine therapy for radical treatment of AIT type 1 and type 2 is shown in spite of low radioiodine capture. However, this issue requires further investigation and discussion. Plasmapheresis and thyroidectomy are used for rapid restoration of euthyroidfunction in severe patients.

Background: Agranulocytosis occurs in 0.2–0.5% of patients treated with the antithyroid drugs (ATDs) methimazole and propylthiouracil. The objectives of this study were to evaluate the risk of ATD-related agranulocytosis in patients with amiodarone-induced thyrotoxicosis (AIT), and to compare it with the agranulocytosis risk in patients with thyrotoxicosis due to other etiologies treated with ATDs. Methods: This was a retrospective cohort study. Participants were 14,781 adult patients with thyrotoxicosis, newly treated with an ATD between January 1, 2002, and December 31, 2015. Among them were 593 patients treated by ATDs due to AIT. The main outcome measures were incidence rates and crude and adjusted hazard ratios using univariate and multivariable Cox regression models for ATD-related agranulocytosis within one year of treatment initiation, in association with AIT. Results: Agranulocytosis occurred in 28 (0.19%) of patients newly treated with methimazole or propylthiouracil during the first year of follow-up. Of these 28 patients, 8/593 (1.35%) were AIT patients and 20/14,188 (0.14%) were thyrotoxic patients that was not AIT related (p < 0.001). Incidence rates were 22 (9.47–43.36) cases/1000 person-years of follow-up in AIT, and 1.79 (1.09–2.76)/1000 person-years of follow-up in non-AIT thyrotoxicosis (p < 0.0001). In univariate Cox regression analysis, risk for ATD agranulocytosis associated with AIT was 9.71 (4.28–22.05) compared to the risk in non-AIT thyrotoxicosis. In a multivariable model, adjusting for age, sex, body mass index, smoking history, year of cohort entry, diabetes mellitus, hypertension, renal failure, beta blockers, calcium channel blockers, anti-aggregants, and dose of ATDs, the risk associated with AIT was 5.70 (2.14–15.21). In a model adjusted for a propensity score to receive amiodarone, risk for ATD agranulocytosis associated with AIT was 6.32 (1.22–32.70). Conclusions: ATD use is associated with a higher risk for agranulocytosis in patients with AIT. [ABSTRACT FROM AUTHOR]

Agata Czarnywojtek,1,2,* Maria Teresa Płazińska,3,* Małgorzata Zgorzalewicz-Stachowiak,4 Kosma Woliński,1 Adam Stangierski,1 Izabela Miechowicz,5 Joanna Waligórska-Stachura,1 Paweł Gut,1 Leszek Królicki,3 Maja Zioncheck,6 Marek Ruchała1 1Department of Endocrinology, Metabolism and Internal Medicine, 2Department of Pharmacology, Poznan University of Medical Sciences, Poznan, 3Nuclear Medicine Department, Medical University of Warsaw, Warsaw, 4Department of Health Prophylaxis, Laboratory of Medical Electrodiagnostics, 5Department of Computer Science and Statistics, 6Poznan University of Medical Sciences, Poznan, Poland *These authors contributed equally to this work Aim: This study aims to explore and compare the efficacy of radioiodine treatment (RIT) in hyperthyroid and euthyroid patients who have been treated with amiodarone (AM) in the past or are currently undergoing AM treatment. Clinical observation of a group of patients with amiodarone-induced hypothyroidism during a 12-month follow-up period was used for comparison.Design: This was a observational, two-centered study. Patients were assessed at baseline and at 2 months, 6 months, 8 months, and 12 months after RIT.Patients: Group A: At baseline (61 males [M] and 17 females [F], mean age 50±19 years), there were 78 euthyroid patients with cardiac arrhythmias, who were treated with AM and developed amiodarone-induced thyrotoxicosis, and currently require retreatment with AM. Group B: Hyperthyroid patients (92 M and 26 F, mean age 72±11.8 years) after AM therapy in the past. Group C: Hyperthyroid patients (66 M and 13 F, mean age 63.9±13.2 years) currently treated by AM. Group D: Hypothyroid patients (6 M and 16 F, mean age 61.4±10.4 years) after AM therapy. The patients from Groups A, B, and C were retreated with AM after ~3–6 weeks of RIT.Results: In Group A, after 12 months of RIT therapy, recurrent thyrotoxicosis was observed in six (7.7%) cases, and persistent hypothyroidism was diagnosed in 42 (53.8%) cases. In Group B, hyperthyroidism occurring during treatment with AM was found in 40 (33.9%) patients, and permanent hypothyroidism was observed in eleven (12.5%) cases. After annual follow-up in Group C, nine (11.4%) patients were diagnosed with hypothyroidism, while 27 (34.1%) patients were diagnosed with hyperthyroidism. In Group D, all patients had permanent hypothyroidism and when the concentration of serum thyroid-stimulating hormone was >10 µIU/mL, l-thyroxine was applied.Conclusion: Our study showed that radioiodine administration is advisable in certain circumstances, even in euthyroid patients. It allows for continuation of further long-term AM treatment. Additionally, RIT allows for the reintroduction of AM therapy that was previously terminated. Hence, it can help control life-threatening tachyarrhythmias and decrease episodes of thyrotoxicosis. Keywords: amiodarone, amiodarone-induced thyrotoxicosis, amiodarone-induced hypothyroidism, radioactive iodine, radioiodine treatment, paroxysmal atrial fibrillation, ventricular tachycardia

The article contains abstracts of actual modern international researches dedicated to management of various thyroid pathology and influence of accompanying states.

Characteristics of amiodarone in clinical practice are focused on. Amiodarone pharmacological mode of action and its pro-arrhythmic effect is presented. As well as various side effects that can happen in clinical practice. Special attention is paid to the problem of amiodarone-induced thyrotoxicosis, its classification, diagnosis and treatment. Prospects of new anti-arrhythmic drugs class III, in particular dronedaron are also discussed.

Atrial fibrillation is a common cardiac arrhythmia. Amiodarone is an effective drug used for atrial fibrillation treatment. Various side effects of this drug including amiodarone-induced thyrotoxicosis are discussed. A clinical case is presented to provide data for the differential diagnosis between types 1 and 2 of amiodarone-induced thyrotoxicosis and to define approaches to the treatment.

Background: Amiodarone-induced thyrotoxicosis (AIT) type 2, characterized as a destructive thyroiditis, is well described in the medical literature; however, iodine-induced thyrotoxicosis (IIT) is not, though the latter has similar features and can be managed similarly. Case presentation: We present a 17-year-old female who presented with a history of an intermittent goiter with thyroid function tests (TFTs): thyroid-stimulating hormone (TSH)<0.015 (0.4–4 μU/mL), free thyroxine (T4)≥6 (0.7–2.1 ng/dL) and total triiodothyronine (T3) 651 (50–200 mg/dL). Thyroid antibodies were all negative. Despite methimazole therapy for 6 weeks, hyperthyroidism proved refractory to medical management. 123I scan uptake was suppressed. With hyperthyroidism being recalcitrant to therapy, a nutritional history revealed consumption of an iodine supplement containing at least 7 times the recommended daily allowance (RDA) for 5 years, contributing to the Jod-Basedow phenomenon. Urinary spot and 24-hour urinary iodine were both elevated. Though a surgical consult was obtained, surgery was cancelled once TFTs improved and then normalized with steroid therapy. The TFTs and urinary iodine levels remained normal post steroid therapy. Conclusions: We suggest that in addition to the need for a thorough nutritional history, a trial of corticosteroids should be utilized in the management of IIT which can present with findings similar to AIT type 2 which is recalcitrant to thionamide therapy. If successful, corticosteroids may delay or prevent surgical management thus avoiding possible complications with the latter approach. [ABSTRACT FROM AUTHOR]

The article analyzes a clinical cases of cardiac arrhythmia and amiodarone-induced thyrotoxicosis (AIT) in a patient with coronary artery disease (CAD). The article discussed the causes of cardiac arrhythmia and the treatment approach for CAD based on coronary angiography (CAG), as well as the efficacy of revascularization by coronary artery bypass grafting. The importance of hormonal tests and thyroid ultrasound before routine CAG is considered, and at least once in 6 months during amiodarone therapy. Differential diagnosis to clarify the type of AIT is carried out, as type I AIT is treated with tireostatics, and type II AIT with glucocorticosteroids. Comorbidity of somatic diseases in cardiological practice is one of the most crucial prognostic factors defining the outcome of the underlying disease. The article considers the choice of treatment approach for patients with CAD based on clinical tests.

Amiodarone is a potent antiarrhythmic agent, indicated for the treatment of refractory arrhythmias, which may lead to thyrotoxicosis. In these patients, thyroidectomy is a valid therapeutic option. Antithyroid therapy in the immediate preoperative setting and the subsequently accepted minimal delay until thyroidectomy have not been clearly defined yet. The aim of the present study was to show, that total thyroidectomy under general anaesthesia in patients with amiodarone-induced thyrotoxicosis (AIT) is safe without necessarily obtaining an euthyroid state preoperatively. We conducted a retrospective cohort study of prospectively gathered data on 11 patients undergoing total thyroidectomy under general anaesthesia between January 2008 and December 2013 for AIT at our University Hospital. All patients were preoperatively treated with carbimazole, steroids and β-receptor antagonists. Additionally, 3 patients received potassium perchlorate and in one patient carbimazole was changed to propylthiouracil. Plasmapheresis was performed in 3 patients. Only one patient was euthyroid at the time of operation. There were no significant intra- and postoperative complications, especially no signs of thyroid storm. One patient could postoperatively be removed from the cardiac transplant waiting list due to improved cardiac function. Improvements in the interdisciplinary surgical management for AIT between cardiologists, endocrinologists, anaesthetists and endocrine surgeons provide the basis of safe total thyroidectomy under general anaesthesia in hyperthyroid state. Early surgery without long delay for medical antithyroid treatment (with its potential negative side effects) is recommended. [ABSTRACT FROM AUTHOR]

Amiodarone is an effective medication for the treatment of cardiac arrhythmias. Originally developed for the treatment of angina, it is now the most frequently prescribed antiarrhythmia drug despite the fact that its use is limited because of potential serious side effects including adverse effects on the thyroid gland and thyroid hormones. Although the mechanisms of action of amiodarone on the thyroid gland and thyroid hormone metabolism are poorly understood, the structural similarity of amiodarone to thyroid hormones, including the presence of iodine moieties on the inner benzene ring, may play a role in causing thyroid dysfunction. Amiodarone-induced thyroid dysfunction includes amiodarone-induced thyrotoxicosis (AIT) and amiodarone-induced hypothyroidism (AIH). The AIT develops more commonly in iodine-deficient areas and AIH in iodine-sufficient areas. The AIT type 1 usually occurs in patients with known or previously undiagnosed thyroid dysfunction or goiter. The AIT type 2 usually occurs in normal thyroid glands and results in destruction of thyroid tissue caused by thyroiditis. This is the result of an intrinsic drug effect from the amiodarone itself. Mixed types are not uncommon. Patients with cardiac disease receiving amiodarone treatment should be monitored for signs of thyroid dysfunction, which often manifest as a reappearance of the underlying cardiac disease state. When monitoring patients, initial tests should include the full battery of thyroid function tests, thyroid-stimulating hormone, thyroxine, triiodothyronine, and antithyroid antibodies. Mixed types of AIT can be challenging both to diagnose and treat and therapy differs depending on the type of AIT. Treatment can include thionamides and/or glucocorticoids. The AIH responds favorably to thyroid hormone replacement therapy. Amiodarone is lipophilic and has a long half-life in the body. Therefore, stopping the amiodarone therapy usually has little short-term benefit. [ABSTRACT FROM PUBLISHER]

Amiodarone is a class 3 antiarrhythmic drug which may be associated with thyroid dysfunction. Amiodarone-induced thyrotoxicosis (AIT) is classified as type 1 (AIT 1; which may develop in the presence of latent autoimmune hyperthyroid condition) or type 2 (AIT 2; which develops in an apparently normal thyroid resulting from destructive thyroiditis). AIT 1 routinely requires treatment with thionamides, whereas AIT 2 is treated with steroids. Resistance to the conventional treatment of hyperthyroidism is not commonly found in clinical practice. This report discusses a case of AIT 2 resistant to conventional treatment. Despite being on high doses of carbimazole and steroids (prednisolone), the patient remained thyrotoxic. Cholestyramine, a bile salt sequestrant, was used as an adjunctive therapy resulting in significant clinical and biochemical improvement. The patient subsequently became euthyroid and is being followed up in endocrine clinic. [ABSTRACT FROM AUTHOR]