Category: Thyroid

Monitor: 2

2 - AMIODARONE-INDUCED THYROTOXICOSIS WITH UNDERLYING CARDIAC ARRHYTHMIA: A CARDIO-ENDOCRINE CONUNDRUM

Friday, Apr 26
11:30 AM – 12:00 PM

Objective :

To report an interesting case of Amiodarone-Induced Thyrotoxicosis(AIT).
AIT can occur from increased T3 and T4 production(Type I) or destructive thyroiditis leading to increased release of T3 and T4(Type II AIT). 


Methods : The Clinical and paraclinical data of the patient are presented


Results :

A 39-year-old female with nonischemic cardiomyopathy with biventricular implantable cardioverter defibrillator (ICD) and multiple shocks for ventricular fibrillation (VF), was in the cardiology clinic for follow up. She had been on Amiodarone for approximately 1.5 years after failing a trial of Sotalol due to QTc prolongation. TSH and free T4 values before starting Amiodarone were 2.29 mIU/L (0.35-4.94 mIU/L) and 0.9 ng/dL (0.70-1.48 ng/dL). For 2 months, the patient noted a 30lb weight loss as well as worsening weakness, diarrhea, and tremulousness. Subsequent thyroid function test showed an undetectable TSH and a free T4 of 5.41 ng/dL. Amiodarone was stopped.
Technetium-99m uptake scan suggested Type II AIT so corticosteroids were started. After 7 months of treatment, TSH was 3.19 mIU/L, and free T4 was 0.9 ng/dL. The patient had an ICD shock for VF 1-year after stopping Amiodarone and was started on mexiletine. Within the following month, the patient was admitted twice for palpitations and an additional ICD shock. She continues her steroid taper. She had TSH of 5.69 mIU/L and free T4 of 0.73 ng/dL. 1-year post amiodarone cessation.


Discussion : We need to be vigilant with regards to AIT, particularly with underlying cardiomyopathy and arrhythmia. AIT with severe left ventricular dysfunction is associated with an increased risk of fatal cardiac events. There may be a benefit to continue amiodarone if prescribed for life-threatening ventricular arrhythmia but patients who remain on amiodarone during corticosteroid treatment for Type II AIT are at risk for recurrent thyrotoxicosis. Data is limited to guide clinicians on patients with arrhythmia on amiodarone who develop thyroid dysfunction to discontinue or remain on the drug; this has implications morbidity and mortality. Thyroid ablation may be considered for AIT if continuing amiodarone is necessary, some patients with Type II AIT develop transient or permanent hypothyroidism when the hyperthyroidism resolves. For these patients who develop hypothyroidism the safety and theoretical risk associated with restarting Amiodarone remains unclear.


Conclusion : Differentiating between the two types of AIT is critical, as they differ in both management and outcome. The symptoms may lag after starting Amiodarone use for up to 2-3 years, requiring a high clinical index of suspicion. Data is limited in regards to continuation of Amiodarone in patients with AIT.

Faisal Aljehani

Fellow
Division of Endocrinology, Diabetes & Medical Genetics, Medical University of South Carolina, Charleston-SC, and Jeddah University, Saudi Arabia.
Mount Pleasant, South Carolina

Faisal Aljehani has completed his medical school degree and received His M.B.B.S from King Abdul Aziz University Faculty of Medicine in Saudi Arabia. He is a board-certified internist who did his residency training in University of Utah, Salt Lake City. Now, he is a fellow in the division of Endocrinology, Diabetes & Medical Genetics at the Medical University of South Carolina (MUSC) in Charleston, South Carolina since July 2018.

Nicoleta Sora

Assistant Professor
Division of Endocrinology, Diabetes & Medical Genetics, Medical University of South Carolina .
Charleston, South Carolina

Nicoleta D. Sora, M.D., is an assistant professor of Medicine and Endocrinology in the division of endocrinology, diabetes, and metabolic diseases at the Medical University of South Carolina (MUSC) in Charleston, South Carolina. She is the Program Director of the Endocrinology Fellowship at MUSC.
In 1997, Dr. Sora received her medical degree from the University of Medicine and Pharmacy, Timisoara, Romania. She completed her internal medicine residency at the University of Connecticut affiliated hospital, Saint Vincent's Medical Center, before starting an endocrinology fellowship in 2009 at MUSC. In 2011, after completing her fellowship in endocrinology, she did an extra year of advanced fellowship training focusing on lipid and lipoprotein metabolism as well as cardiovascular preventive management. Dr. Sora has been on faculty at MUSC since 2012. She is board certified in internal medicine as well as endocrinology, diabetes, and metabolism.
Dr. Sora looks forward to providing care for patients with endocrine disorders with particular interest in obesity, metabolic syndrome, lipid, and thyroid disorders.

Faisal Aljehani

Faisal Aljehani

Fellow
Division of Endocrinology, Diabetes & Medical Genetics, Medical University of South Carolina, Charleston-SC, and Jeddah University, Saudi Arabia.
Mount Pleasant, South Carolina

Faisal Aljehani has completed his medical school degree and received His M.B.B.S from King Abdul Aziz University Faculty of Medicine in Saudi Arabia. He is a board-certified internist who did his residency training in University of Utah, Salt Lake City. Now, he is a fellow in the division of Endocrinology, Diabetes & Medical Genetics at the Medical University of South Carolina (MUSC) in Charleston, South Carolina since July 2018.