Evaluation and Treatment of Amiodarone-Induced Thyroid Disorders

Exploring Current Diagnosis and Management of Amiodarone-induced Thyrotoxicosis

Amiodarone, commonly used to treat various types of arrhythmias, can potentially lead to catastrophic adverse effects like amiodarone-induced thyrotoxicosis (AIT). This review offers insights into diagnosing and managing AIT, involving thyroid function tests, imaging techniques, and strategies to prevent cardiac deterioration and reduce mortality. The approach to managing AIT has shifted from focusing on thyrotoxicosis control to a broader strategy that includes preventing heart deterioration, hospitalizations, and reducing mortality. Healthcare professionals should consider the patient's need for amiodarone, side effects, coexisting conditions, and personal perspective. Routine thyroid function monitoring and collaboration across medical specialties are essential for comprehensive AIT management. Effective management of AIT is crucial to diminish mortality and morbidity. Pharmacological treatment can be initiated. Further intervention such as thyroidectomy is recommended, especially in cases where cardiac status is deteriorating and amiodarone continuation is necessary. In conclusion, early diagnosis and timely treatment through interdisciplinary collaboration according to specific individual case are crucial to reduce morbidity and mortality in AIT patients.

Incidence and Risk Factors for Amiodarone-Induced Thyroid Dysfunction: A Nationwide Retrospective Cohort Study

BACKGROUND

Amiodarone is an effective anti-arrhythmic drug; however, it is frequently associated with thyroid dysfunction. The aim of this study was to investigate the incidence and risk factor of amiodarone-induced dysfunction in an iodine-sufficient area.

METHODS

This retrospective cohort study included 27,023 consecutive patients treated with amiodarone for arrhythmia, using the Korean National Health Insurance database. A Cox regression analysis was performed to determine independent risk factors for amiodarone-induced thyroid dysfunction.

RESULTS

During a mean follow-up period of 6.4 years, 1326 (4.9%) patients developed thyrotoxicosis and 3121 (11.5%) developed hypothyroidism. The incidence rate of amiodarone-induced thyrotoxicosis (AIT) and amiodarone-induced hypothyroidism (AIH) was 6.92 and 17.1 per 1000 person-years, respectively. In the multivariate analysis, chronic kidney disease (CKD) [hazard ratio (HR) 1.46, 95% confidence interval (CI) 1.06-1.99], and Hashimoto's thyroiditis (HR 2.00, 95% CI 1.31-3.07) were associated with AIT, while female sex (HR 1.22, 95% CI 1.14-1.32), diabetes (HR 1.14, 95% CI 1.06-1.24), CKD (HR 1.18, 95% CI 1.05-1.34), and Hashimoto's thyroiditis (HR 2.26, 95% CI 1.66-3.09) were associated with AIH.

CONCLUSIONS

The incidence of AIH was higher compared with AIT in an area with sufficient iodine intake. Several potential risk factors for AIT and AIH were identified. When amiodarone treatment is considered for patients, particularly those at a high risk of thyroid dysfunction, it is warranted to perform regular thyroid function assessments.

The Safety Profile of Amiodarone Among Older Adults (Age ≥75 Years): A Pharmacovigilance Study from the FDA Data

BACKGROUND

Amiodarone is a widely used antiarrhythmic agent with significant toxicities and drug interactions more likely to affect older adults. Nevertheless, data regarding amiodarone safety in this population are limited.

METHODS

We conducted a retrospective analysis of FDA [Food and Drug Administration] Adverse Event Reporting System (FAERS) data from 2003 to 2024. Reports with amiodarone as the primary suspect were compared with other antiarrhythmics (sotalol, dronedarone, flecainide, propafenone, dofetilide). Disproportionality analysis assessed reporting odds ratios (RORs) for predefined adverse events in adults (<75 years) and older adults (≥75 years). Interaction analysis evaluated differences between age groups.

RESULTS

Among 9196 amiodarone FAERS reports, 4129 (44.9%) involved older adults. Hyperthyroidism (ROR 39.1; 95% confidence interval [CI], 25-61 and ROR 23.4; 95% CI, 11-49.8) and hypothyroidism (ROR 36.9; 95% CI, 15.2-89.8 and ROR 24.5; 95% CI, 11.5-52.1) were substantially over-reported in amiodarone users among both adults and older adults, respectively. Drug-induced liver injury and peripheral neuropathy were also over-reported without a significant age interaction. Interstitial lung disease was reported more frequently in amiodarone users overall, with significantly higher reporting in older adults (ROR 11.4; 95% CI, 6.9-18.6 vs 4.9; 95% CI, 3.4-7.0; Pinteraction = .007). Bradycardia was also over-reported in older adults compared with adults (ROR 1.6; 95% CI, 1.3-2 vs 1.0; 95% CI, 0.8-1.3; Pinteraction = .003). Torsades de pointes/QT prolongation were less frequently reported in both age groups.

CONCLUSIONS

In this global postmarketing study, interstitial lung disease and bradycardia were more frequently reported in older adults treated with amiodarone. These findings support vigilant monitoring for these adverse events, particularly in older patients.

Iodine and Hyperthyroidism: A Double-Edged Sword

OBJECTIVE

This article serves as an update to a 1995 review by Braverman and Roti that was publishsed in the inaugural issue of Endocrine Practice.

METHODS

We searched PubMed for relevant English-language literature and identified additional papers cited in recent reviews.

RESULTS

Iodine is a trace element found in the Earth's crust that is necessary for the biosynthesis of thyroid hormones. Excessive iodine exposure can lead to hyperthyroidism due to the failure of normal homeostatic mechanisms. Iodine-induced hyperthyroidism occurs most frequently in historically iodine-deficient regions, where there is an increased prevalence of autonomously functioning thyroid nodules, but this can also occur in regions with optimal background iodine intakes. Potential sources of iodine excess include iodized salt, seaweed, iodine-containing supplements, drinking water, iodinated contrast media, and amiodarone. In addition to being a potential cause of hyperthyroidism, inorganic iodine may be used to treat Graves' hyperthyroidism and thyroid storm, although there is a risk that this may worsen hyperthyroidism in some patients. Inorganic iodine is also used as a preoperative treatment to reduce thyroid vascularity before thyroidectomy.

CONCLUSION

Recognizing potential sources of iodine and patients who may be particularly vulnerable to the effects of iodine excess can help to identify and prevent hyperthyroidism.

Amiodarone Advances the Apoptosis of Cardiomyocytes by Repressing Sigmar1 Expression and Blocking KCNH2-related Potassium Channels

BACKGROUND

Heart failure (HF) is the ultimate transformation result of various cardiovascular diseases. Mitochondria-mediated cardiomyocyte apoptosis has been uncovered to be associated with this disorder.

OBJECTIVE

This study mainly delves into the mechanism of the anti-arrhythmic drug amiodarone on mitochondrial toxicity of cardiomyocytes.

METHODS

The viability of H9c2 cells treated with amiodarone at 0.5, 1, 2, 3, and 4 μM was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and Sigmar1 expression was examined by quantitative real-time PCR (qRTPCR). After transfection, the viability, apoptosis, reactive oxygen species (ROS) level, mitochondrial membrane potential (MMP), and potassium voltage-gated channel subfamily H member 2 (KCNH2) expression in H9c2 cells were assessed by MTT, flow cytometry, ROS assay kit, mitochondria staining kit, and Western blot.

RESULTS

Amiodarone at 1-4 μM notably weakened H9c2 cell viability with IC50 value of 2.62 ± 0.43 μM. Amiodarone at 0.5-4 μM also evidently suppressed the Sigmar1 level in H9c2 cells. Amiodarone repressed H9c2 cell viability and KCNH2 level and triggered apoptosis, ROS production and mitochondrial depolarization, while Sigmar1 upregulation reversed its effects. Moreover, KCNH2 silencing neutralized the effect of Sigmar1 up-regulation on H9c2 cell viability, apoptosis, and ROS production.

CONCLUSION

Amiodarone facilitates the apoptosis of H9c2 cells by restraining Sigmar1 expression and blocking KCNH2-related potassium channels.

The Complex Web of Interferences With Thyroid Function Tests

OBJECTIVE

Thyroid disorders are common. Serum thyroid stimulating hormone is frequently measured and is the single best initial biomarker to diagnose thyroid disease. Automated immunoassays used to evaluate thyroid function are susceptible to interferences that can affect test results and therefore clinical decisions. In this comprehensive review, our aim is to discuss common assay and drug interferences leading to abnormal thyroid function tests.

METHODS

Authors conducted a literature review of PubMed to include studies on drug related and laboratory assay interferences leading to primary and secondary thyroid dysfunction in addition to interferences with thyroid hormone replacement and thyroid function tests.

RESULTS

Overall, there are several assay interferences as well as drug interferences leading to primary thyroid dysfunction including iodine-containing drugs such as amiodarone, lithium, immune checkpoint inhibitors and tyrosine kinase inhibitors, drug interferences leading to secondary thyroid dysfunction such as glucocorticoids, and drug interferences affecting thyroid hormone absorption, metabolism, and thyroid binding globulin levels. In addition, assay interferences from biotin, heterophile antibodies, macro-thyrotropin or anti-streptavidin antibodies may occur without underlying thyroid dysfunction, leading to abnormal thyroid function tests.

CONCLUSION

For appropriate patient management, it is imperative to identify assay interferences when discrepancies between clinical presentation and thyroid function test results are noted.

The possible effects of chronic administration of amiodarone hydrochloride on the seminiferous tubules of adult male albino rats: histological and biochemical study

Amiodarone hydrochloride is an antiarrhythmic agent that is widely prescribed. However, it has serious side effects that approximately affect the whole body organs. In our study, we aimed to assess the possible effects of chronic administration of two different doses of amiodarone hydrochloride on the oxidative and inflammatory parameters as well as the histological morphology and ultrastructure of the seminiferous tubules of adult male albino rats. Forty rats were divided into four groups; Control group 1: each rat did not receive any drugs at all. Control group 2: each rat received 3 ml of 0.16% methylcellulose, orally and daily for 4 weeks. Low dose amiodarone group: each rat received 3 ml of 0.16% methylcellulose contained 3.6 mg amiodarone, orally and daily for 4 weeks. High dose amiodarone group: each rat received 3 ml of 0.16% methylcellulose contained 7.2 mg amiodarone, orally and daily for 4 weeks. Blood samples were collected for measuring serum levels of malondialdehyde, superoxide dismutase, interleukin-6 and tumor necrosis factor-alpha. Testes specimens were examined to assess the morphological changes and the level of expression of caspase-3 apoptotic marker. The results indicated that; amiodarone hydrochloride could induce a dose-dependent toxicity, causing oxidative stress, inflammation, cellular degeneration, deposition of collagen and enhanced apoptosis in the seminiferous tubules.

Adverse drug reaction signals mining comparison of amiodarone and dronedarone: a pharmacovigilance study based on FAERS

Background

Amiodarone and dronedarone are both class III antiarrhythmic medications used to treat arrhythmias. The objective of this study was to enhance the current understanding of adverse drug reaction (ADR) associated with amiodarone and dronedarone by employing data mining methods on the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS), and providing a reference for safe and reasonable clinical use.

Methods

The ADR records were selected by searching the FAERS database from 2011 Q3 to 2023 Q3. The disproportionality analysis algorithms, including Reporting Odds Ratio (ROR), Proportional Reporting Ratio (PRR), Bayesian Confidence Propagation Neural Network (BCPNN), and Empirical Bayesian Geometric Mean (EBGM), were used to detect signals of amiodarone-related and dronedarone-related ADRs. The ADR profiles of amiodarone and dronedarone categorized by organ toxicity were compared through the Z-test and the Fisher exact test.

Results

9,295 reports specifically mentioned the use of amiodarone and 2,485 reports mentioned the use of dronedarone among 9,972,109 reports, with the majority of ADRs occurring in males over 60 years old. The United States was responsible for the highest proportion of reported ADRs. Significant system organ classes (SOC) for both included Cardiac disorders, Respiratory, thoracic and mediastinal disorders, and Investigations, etc. At the preferred terms (PTs) level, the more frequent ADR signals for amiodarone were drug interaction (n = 856), hyperthyroidism (n = 758), and dyspnoea (n = 607), while dronedarone were atrial fibrillation (n = 371), dyspnoea (n = 204), and blood creatinine increased (n = 123). Notably, unexpected ADRs, including electrocardiogram T wave alternans (n = 16; EBGM05 = 231.27), accessory cardiac pathway (n = 11; EBGM05 = 140), thyroiditis (n = 178; EBGM05 = 125.91) for amiodarone, and cardiac ablation (n = 11; EBGM05 = 31.86), cardioversion (n = 7; EBGM05 = 22.69), and dysphagia (n = 47; EBGM05 = 3.6) for dronedarone, were uncovered in the instructions. The analysis also revealed significant differences in the ADR profiles of amiodarone and dronedarone, with dronedarone showing higher proportions of cardiac toxicity but lower thyroid toxicity compared to amiodarone.

Conclusion

These findings underscore the significance of vigilantly monitoring and comprehending the potential risks linked to the use of amiodarone and dronedarone. New ADRs discovered and clear ADR profiles of amiodarone and dronedarone enhance a thorough understanding of these drugs, which is essential for clinicians to ensure safe use of amiodarone and dronedarone.

Amiodarone Therapy: Updated Practical Insights

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.

Risks of Iodine Excess

Iodine is a micronutrient that is required for thyroid hormone synthesis. The iodide cycle in thyroid hormone synthesis consists of a series of transport, oxidation, organification, and binding/coupling steps in thyroid follicular cells. Common sources of iodine include the consumption of an iodine-rich diet or iodine fortified foods, the administration of amiodarone, iodine-containing supplements, or iodinated contrast media, and other miscellaneous sources. Methods to assess population iodine status include the measurement of urinary iodine concentrations, blood thyroglobulin levels, prevalence of elevated neonatal TSH levels, and thyroid volume. Although excessive iodine intake or exposure is generally well tolerated, an acute iodine load may result in thyroid dysfunction (hypothyroidism or hyperthyroidism) in certain susceptible individuals due to the failure to escape from the Wolff-Chaikoff effect and to the Jod-Basedow phenomenon, respectively. In this review, we discuss the associations between excessive iodine intake or exposure, with particular focus on iodinated contrast media as a common source of excess iodine in healthcare settings, and risks of incident thyroid dysfunction. We also summarize the risks of iodine excess in vulnerable populations and review current guidelines regarding the screening and monitoring of iodinated contrast-induced thyroid dysfunction. Finally, we discuss the long-term potential nonthyroidal health risks associated with iodine excess and suggest the need for more data to define safe upper limits for iodine intake, particularly in high-risk populations.

The global prevalence of sexual dysfunction in men with thyroid gland disorders: a systematic review and meta-analysis

Introduction

fluctuation in serum levels of thyroid hormones or thyroid-associated dysfunction can negatively affect the sexual behaviors or performance, and disruption in couples` relationship or satisfaction. Thus, this systematic review and meta-analysis study was aimed to investigate the global prevalence of sexual dysfunction in men with thyroid gland disorders (TGD).

Methods

this systematic review and meta-analysis study conducted based on PRISMA statement criteria regarding the available evidences representing the prevalence of sexual dysfunction in men with TGD. The initial searching process was applied on July, 2023. In this era, the main keywords of "Prevalence", "Sexual disorders", "Sexual disorder", "Sexual dysfunction", "Male sexual dysfunction", "Erectile dysfunction", "Males", "Men", "Thyroid disorders", "Thyroid diseases", "Hyperthyroidism", "Thyroid", and "Thyroiditis" were hired. Also, "AND" and "OR" operators were used for keywords combination. All intended studies were searched using the databases of Web of Science, Google Scholar, Scopus, ScienceDirect, PubMed, and Embase. Random effects model was used to perform the analysis and the heterogeneity of the studies was assessed through I2 index. Data analysis was applied with CMA software (v.2).

Results

following the assessment of 17 eligible studies with a sample size of 501 individuals, the global prevalence of male sexual dysfunction with TGD was found 51.5% (95% CI:38.7-64). Also, the prevalence of male sexual dysfunction in hypothyroidism and hyperthyroidism cases was 59.1% (95% CI:37.2-77.8) and 41.5% (95% CI:25.9-59.1), respectively. The meta-regression analysis showed that following incremental trend in sample size, the global prevalence of male sexual dysfunction with TGD decreases. This assessment also revealed that the prevalence of male sexual dysfunction increases with the year of study conduction, significantly (p < 0.05).

Conclusion

the global prevalence of sexual dysfunction in men with TGD was found relatively high. also, the highest prevalence of sexual disorders was reported in hypothyroid cases. Thus, health policymakers are suggested to inform the individuals prone to this pathology regarding the negative effects of TGD on sexual dysfunction. Besides, TGD-affected cases can prevent sexual disorders and unpleasant consequences through timely medical treatments.

Atypical Clinical Courses of Graves' Disease Confound Differential Diagnosis of Hyperthyroidism

BACKGROUND

This study examined the appropriateness of the current paradigm for differential diagnosis of painless thyroiditis and Graves' disease (GD) in patients with thyrotoxicosis.

METHODS

We retrospectively evaluated the clinical course of 343 consecutive patients with hyperthyroidism diagnosed by Tc-99m pertechnetate thyroid uptake (TcTU) testing at our hospital from January 2011 to December 2017.

RESULTS

Of the 263 patients with normal or high TcTU levels (≥1.0%), 255 (97%) had unequivocal GD and 5 had spontaneous remission GD or atypical GD. Of the 10 patients with low TcTU levels (<1.0% and ≥0.5%), 7 had GD, while others had subclinical GD, spontaneous remission GD with later relapse, and painless thyroiditis. Of those with very low TcTU levels (<0.5%), most had thyroiditis (painless thyroiditis, 33/67 [49%]; subacute thyroiditis, 29/67 [43%]), and some were positive for anti-TSH receptor antibodies.

CONCLUSION

Given that atypical GD may confound the diagnosis of thyrotoxicosis, it is essential to follow the patient as a tentative diagnosis, whatever the diagnosis. This is the first report clearly demonstrating that so far there is no gold standard for the diagnosis of GD. It is therefore urgent to establish a consensus on the definition of GD so that the specificity and sensitivity of future diagnostic tests can be determined.

Hyperthyroidism

Thyrotoxicosis causes a variety of symptoms and adverse health outcomes. Hyperthyroidism refers to increased thyroid hormone synthesis and secretion, most commonly from Graves' disease or toxic nodular goitre, whereas thyroiditis (typically autoimmune, viral, or drug induced) causes thyrotoxicosis without hyperthyroidism. The diagnosis is based on suppressed serum concentrations of thyroid-stimulating hormone (TSH), accompanied by free thyroxine and total or free tri-iodothyronine concentrations, which are raised (overt hyperthyroidism) or within range (subclinical hyperthyroidism). The underlying cause is determined by clinical assessment, detection of TSH-receptor antibodies and, if necessary, radionuclide thyroid scintigraphy. Treatment options for hyperthyroidism include antithyroid drugs, radioactive iodine, and thyroidectomy, whereas thyroiditis is managed symptomatically or with glucocorticoid therapy. In Graves' disease, first-line treatment is a 12-18-month course of antithyroid drugs, whereas for goitre, radioactive iodine or surgery are preferred for toxic nodules or goitres. Evidence also supports long-term treatment with antithyroid drugs as an option for patients with Graves' disease and toxic nodular goitre.

The Utility of Intravenous Methylprednisolone as an Adjunct Treatment for Drug-Resistant Amiodarone-Induced Thyrotoxicosis

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.

2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation" provides recommendations to guide clinicians in the treatment of patients with atrial fibrillation.

METHODS

A comprehensive literature search was conducted from May 12, 2022, to November 3, 2022, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through November 2022, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Atrial fibrillation is the most sustained common arrhythmia, and its incidence and prevalence are increasing in the United States and globally. Recommendations from the "2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" and the "2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" have been updated with new evidence to guide clinicians. In addition, new recommendations addressing atrial fibrillation and thromboembolic risk assessment, anticoagulation, left atrial appendage occlusion, atrial fibrillation catheter or surgical ablation, and risk factor modification and atrial fibrillation prevention have been developed.

Monitoring thyroid function during amiodarone use

Amiodarone is an antiarrhythmic drug used to treat cardiac tachyarrhythmias. It has many adverse effects, with thyroid dysfunction one of the most notable. Through various mechanisms, both thyrotoxicosis and hypothyroidism can occur secondary to amiodarone therapy. There are two types of amiodarone-induced thyrotoxicosis: type 1 occurs in those with pre-existing thyroid disease and is treated with thionamide, whereas type 2 occurs in those without and is treated with glucocorticoids. Patients with amiodarone-induced hypothyroidism may be given levothyroxine to replace thyroid hormone, but in some cases, the appropriate management may be cessation of amiodarone.

2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Patients With Atrial Fibrillation" provides recommendations to guide clinicians in the treatment of patients with atrial fibrillation.

METHODS

A comprehensive literature search was conducted from May 12, 2022, to November 3, 2022, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through November 2022, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Atrial fibrillation is the most sustained common arrhythmia, and its incidence and prevalence are increasing in the United States and globally. Recommendations from the "2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" and the "2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" have been updated with new evidence to guide clinicians. In addition, new recommendations addressing atrial fibrillation and thromboembolic risk assessment, anticoagulation, left atrial appendage occlusion, atrial fibrillation catheter or surgical ablation, and risk factor modification and atrial fibrillation prevention have been developed.

Advances in Thyroid Function Tests: Precision Diagnostics and Clinical Implications

This narrative review explores the evolving field of thyroid function testing, explicitly highlighting the significance of precision diagnostics and their substantial impact on clinical practice. Commencing with a comprehensive examination of the historical progression of thyroid diagnostics, the discourse proceeds to explore recent developments, highlighting the paramount importance of accuracy in testing methods. The primary issue under consideration is the crucial requirement for accuracy in the field of therapeutic practice. The review critically examines the problems related to the interpretation, standardization, and ethical considerations in examining advanced laboratory techniques, novel biomarkers, and state-of-the-art technologies like immunoassays, molecular testing, and automation. The focus on the paradigm shift towards precision diagnostics brings attention to the complex connection between test results and their direct influence on patient care. This investigation expands upon the incorporation of imaging and molecular diagnostics, highlighting the rising significance of precision in customizing treatment strategies. In summary, the study provides a prospective viewpoint, recognizing the persistent obstacles and highlighting the want for dependable, uniform methodologies in thyroid diagnostics. This narrative's primary objective is to guide physicians, researchers, and stakeholders in effectively navigating the intricate nature of contemporary thyroid function tests, with a particular emphasis on resolving the fundamental issue of precision.

[Type 2 amiodarone-induced thyrotoxicosis: prevalence, time and predictors of development]

BACKGROUND

Amiodarone takes a leading position in arrhythmological practice in the prevention and relief of various cardiac arrhythmias. Type 2 amiodarone-induced thyrotoxicosis is a frequent side effect of the drug. It is the most complex type of thyroid dysfunction both in terms of the severity of clinical manifestations, and in terms of understanding the mechanisms of pathogenesis, possibility of differential diagnosis and providing effective treatment. Due to the increasing life expectancy of the population, corresponding increase in the frequency of cardiac arrhythmias, the problem does not lose its relevance. Identification of predictors, assessment and prediction of the individual risk of developing this thyroid pathology is a necessity in daily clinical practice for making a reasonable decision when prescribing the drug, determining the algorithm for further dynamic monitoring of the patient.

AIM

To evaluate the structure of amiodarone-induced thyroid dysfunction, prevalence, time and predictors of development type 2 amiodarone-induced thyrotoxicosis in a prospective cohort study. MATERIALS AND METHODS: The study involved 124 patients without thyroid dysfunction who received amiodarone therapy for the first time. Evaluation of the functional state of the thyroid gland was performed initially, after prescribing the drug for the first 3 months 1 time per month, in the future - every 3 months. The follow-up period averaged 12-24 months. The end of the observation occurred with the development of amiodaron-induced thyroid dysfunction or patient's refusal to further participate in the study. For the differential diagnosis of the type of amiodarone-induced thyrotoxicosis, the level of anti-TSH receptor antibodies and thyroid scintigraphy with technetium pertechnetate were determined. The type and frequency of thyroid dysfunction, time and predictors of development type 2 amiodarone-induced thyrotoxicosis were evaluated.

RESULTS

The structure of amiodarone-induced thyroid dysfunction was represented by hypothyroidism in 19,3% (n=24), type 1 thyrotoxicosis in 1,6% (n=2), type 2 thyrotoxicosis in 23,4% (n=29). The median time of its development was 92,0 [69,0;116,0] weeks; the average period of common survival - 150,2±12,6 weeks (95% CI: 125,5-175,0), median - 144±21,7 weeks (95% CI: 101,4-186,6). The main predictors of type 2 amiodarone-induced thyrotoxicosis were: age (OR=0,931; 95% CI: 0,895-0,968; p<0.001), BMI (OR=0,859; 95% CI: 0,762-0,967; p=0,012), time from the start of amiodarone therapy (OR=1,023; 95% CI: 1,008-1,038; p=0,003). Age ≤60 years was associated with increased risk of the dysfunction by 2.4 times (OR=2,352; 95% CI: 1,053-5,253; p=0,037), BMI≤26,6 kg/m2 - 2,3 times (OR=2,301; 95% CI: 1,025-5,165; p=0,043). CONCLUSION: The results allow to personalized estimate the risk of type 2 amiodarone-induced thyrotoxicosis and determine the patient's management tactic.

Development and Validation of a Prediction Model for Incident Hypothyroidism in a National Chronic Kidney Disease Cohort

CONTEXT

Hypothyroidism is a common yet under-recognized condition in patients with chronic kidney disease (CKD), which may lead to end-organ complications if left untreated.

OBJECTIVE

We developed a prediction tool to identify CKD patients at risk for incident hypothyroidism.

METHODS

Among 15 642 patients with stages 4 to 5 CKD without evidence of pre-existing thyroid disease, we developed and validated a risk prediction tool for the development of incident hypothyroidism (defined as thyrotropin [TSH] > 5.0 mIU/L) using the Optum Labs Data Warehouse, which contains de-identified administrative claims, including medical and pharmacy claims and enrollment records for commercial and Medicare Advantage enrollees as well as electronic health record data. Patients were divided into a two-thirds development set and a one-third validation set. Prediction models were developed using Cox models to estimate probability of incident hypothyroidism.

RESULTS

There were 1650 (11%) cases of incident hypothyroidism during a median follow-up of 3.4 years. Characteristics associated with hypothyroidism included older age, White race, higher body mass index, low serum albumin, higher baseline TSH, hypertension, congestive heart failure, exposure to iodinated contrast via angiogram or computed tomography scan, and amiodarone use. Model discrimination was good with similar C-statistics in the development and validation datasets: 0.77 (95% CI 0.75-0.78) and 0.76 (95% CI 0.74-0.78), respectively. Model goodness-of-fit tests showed adequate fit in the overall cohort (P = .47) as well as in a subcohort of patients with stage 5 CKD (P = .33).

CONCLUSION

In a national cohort of CKD patients, we developed a clinical prediction tool identifying those at risk for incident hypothyroidism to inform prioritized screening, monitoring, and treatment in this population.

The Role of Nuclear Medicine in Benign Thyroid Disease

Since the mid-twentieth century, the radionuclide thyroid scan has been utilized in the management of benign thyroid disorders. In current medical practice, patients with hyperthyroidism are referred for thyroid scintigraphy, while patients with goiters and thyroid nodules are most often evaluated by ultrasound or computed tomography. Since thyroid scintigraphy reflects the functional state of the gland, it provides information that anatomical imaging lacks. Therefore, radionuclide imaging of the thyroid is the imaging modality of choice in the evaluation of the hyperthyroid patient. In addition, patients with so-called subclinical hyperthyroidism often present a diagnostic dilemma to the clinician since the causative factor must be determined for proper patient management. The aim of this manuscript is to illustrate the imaging characteristics of thyroid disorders commonly seen in clinical practice resulting in thyrotoxicosis or pending thyrotoxicosis, so that correlation with clinical presentation and pertinent laboratory data will lead to the correct diagnosis.

A Brief Look at Hashimoto's Disease, Adrenal Incidentalomas, Obesity and Insulin Resistance-Could Endocrine Disruptors Be the Other Side of the Same Coin?

Hashimoto's disease (HD) is the most common cause of hypothyroidism in developed countries. The exact pathomechanism behind it has not been clearly established; however, an interplay of genetic susceptibility, environmental triggers (including diet) and epigenetic factors seems to be involved. Among the latter, increasingly more attention has been paid to some hormonally active substances, known as endocrine disruptors, which are commonly used worldwide. HD has become a condition widely reported in the media, acting as a culprit for inexplicable weight gain, chronic fatigue or weakness. Nevertheless, the recognition of HD is undeniably increasing and represents a major public health burden. At the same time, improving access to imaging tests has increased the number of incidentally diagnosed adrenal tumors. Above all, the widespread use of chest computed tomography (CT) due to the COVID-19 pandemic has contributed to frequent incidental detection of adrenal lesions. Fortunately, a vast majority of these findings are asymptomatic benign tumors with no excessive hormonal activity, and therefore, they are defined as adrenal incidentalomas (AIs). Interestingly, recent studies have indicated that patients with AIs are more prone to obesity and insulin resistance. Although mutual relationships between the thyroid and the adrenal glands have been studied widely, still, little is known about the possible pathophysiological associations between thyroid autoimmunity and the occurrence of adrenal incidentalomas. This article presents a brief review of the common endocrine disorders with a special focus on the frequently coexisting insulin resistance and/or obesity. Furthermore, in response to the recent growing interest in endocrine disruptors, with their transgenerational epigenetic effects that influence hormonal system function, a concise overview of the topic has also been included.

Amiodarone-Induced Myxedema Coma in Elderly Patients: A Systematic Review of Case Reports

This systematic review aimed to explore whether elderly patients administered amiodarone were susceptible to developing myxedema coma. Utilizing the Cochrane guidelines, a comprehensive review of databases such as Medline (PubMed), Science Direct, CINAHL Cochrane, and Google Scholar was undertaken to examine case reports on amiodarone-induced myxedema coma. Following stringent criteria for inclusion, 12 pertinent case reports were identified. These findings suggested a high probability of myxedema coma development in patients who had been administered amiodarone. Specifically, patients who received an oral dosage of 100-200 mg of amiodarone were reported to have developed bradycardia and hypothermia alongside elevated thyroid-stimulating hormone (TSH) levels. Upon diagnosis, the majority of patients were treated with a regimen of levothyroxine and hydrocortisone medication. Despite the myriad potential causes of myxedema coma complicating the diagnosis, it was found that through a combination of clinical symptoms and serum TSH measurements, a confirmed diagnosis could be reached. Furthermore, it was observed that amiodarone-induced myxedema coma responded favorably to treatment with levothyroxine and glucocorticoids.

Thyroid and Aging

Older adults are more vulnerable to the negative effects of excess thyroid hormone and may even be protected by lower levels of thyroid hormone. The diagnosis and management of thyroid disease in older adults needs to account for aging-related changes in function and resilliance.

Therapeutic Plasma Exchange for the Treatment of Hyperthyroidism: Approach to the Patient with Thyrotoxicosis or Antithyroid-Drugs Induced Agranulocytosis

Primary hyperthyroidism is an endocrine disorder characterized by excessive thyroid hormone synthesis and secretion by the thyroid gland. Clinical manifestations of hyperthyroidism can vary from subclinical to overt forms. In rare cases, hyperthyroidism may represent a clinical emergency, requiring admission to an intensive care unit due to an acute and severe exacerbation of thyrotoxicosis, known as a thyroid storm. First-line treatment of hyperthyroidism is almost always based on medical therapy (with thioamides, beta-adrenergic blocking agents, glucocorticoids), radioactive iodine or total thyroidectomy, tailored to the patient’s diagnosis. In cases of failure/intolerance/adverse events or contraindication to these therapies, as well as in life-threatening situations, including a thyroid storm, it is necessary to consider an alternative treatment with extracorporeal systems, such as therapeutic plasma exchange (TPE). This approach can promptly resolve severe conditions by removing circulating thyroid hormones. Here we described two different applications of TPE in clinical practice: the first case is an example of thyrotoxicosis due to amiodarone treatment, while the second one is an example of a severe adverse event to antithyroid drugs (agranulocytosis induced by methimazole).

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

CONTEXT

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

STUDY DESIGN

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Iodine as a potential endocrine disruptor-a role of oxidative stress

PURPOSE

Iodine is an essential micronutrient required for thyroid hormone biosynthesis. However, overtreatment with iodine can unfavorably affect thyroid physiology. The aim of this review is to present the evidence that iodine-when in excess-can interfere with thyroid hormone synthesis and, therefore, can act as a potential endocrine-disrupting chemical (EDC), and that this action, as well as other abnormalities in the thyroid, occurs-at least partially-via oxidative stress.

METHODS

We reviewed published studies on iodine as a potential EDC, with particular emphasis on the phenomenon of oxidative stress.

RESULTS

This paper summarizes current knowledge on iodine excess in the context of its properties as an EDC and its effects on oxidative processes.

CONCLUSION

Iodine does fulfill the criteria of an EDC because it is an exogenous chemical that interferes-when in excess-with thyroid hormone synthesis. However, this statement cannot change general rules regarding iodine supply, which means that iodine deficiency should be still eliminated worldwide and, at the same time, iodine excess should be avoided. Universal awareness that iodine is a potential EDC would make consumers more careful regarding their diet and what they supplement in tablets, and-what is of great importance-it would make caregivers choose iodine-containing medications (or other chemicals) more prudently. It should be stressed that compared to iodine deficiency, iodine in excess (acting either as a potential EDC or via other mechanisms) is much less harmful in such a sense that it affects only a small percentage of sensitive individuals, whereas the former affects whole populations; therefore, it causes endemic consequences.

Protective Role of Amiodarone on Reperfusion Arrhythmia in Patients of Acute Myocardial Infarction with Percutaneous Coronary Intervention Treatment

With the development and popularity of percutaneous coronary intervention (PCI), ischemia-reperfusion injury (IRI) has attracted more and more clinical attention. Reperfusion arrhythmia (RA), one of the common manifestations during and after PCI, can affect the postoperative cardiac function of patients with acute myocardial infarction (AMI). Therefore, effective intervention on RA has important clinical significance. This study observed the effect of amiodarone on reperfusion arrhythmia (RA) after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) and explored its possible mechanism. The results showed that amiodarone had good clinical efficacy in the prevention of RA in patients with AMI after PCI, and it could reduce the levels of serum IL-6, hs-CRP, CK-MB, and cTnI in patients and reduce the damage caused by reperfusion, thereby reducing the occurrence of RA.

The effects of amiodarone on thyroid function in pediatric and adolescent patients

PURPOSE OF REVIEW

Amiodarone-induced thyroid dysfunction is well established. The present review discusses recent literature related to the effects of amiodarone on the thyroid gland and thyroid function in pediatrics.

RECENT FINDINGS

Current guidelines in adults treated with amiodarone recommend baseline thyroid function testing followed by initiation of thyroid hormone monitoring after 3 months on therapy. Two retrospective studies to evaluate amiodarone-induced thyroid dysfunction in children and young adults reveal thyroid dysfunction as soon as 2 weeks after amiodarone initiation with a greater percentage of pediatric patients developing amiodarone-induced hypothyroidism rather than thyrotoxicosis. Although additional studies are needed to determine if AIH is associated with negative impact on growth and neurocognitive development, what is clear is that in both adults and pediatrics, there is low compliance with recommended side effect-monitoring guidelines.

SUMMARY

Pediatric patients are at similarly high risk to develop amiodarone-induced thyroid dysfunction as are adults. It is hoped that through improved education of providers and patients further research into the incidence, the potential risks of amiodarone therapy and the potential benefits of thyroid hormone replacement therapy in patients with AIH will be investigated and reported.