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Thyroid Dysfunction Induced by Amiodarone Therapy Clinical Presentation

  • Author: Mini Gopalan, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
 
Updated: Jul 12, 2016
 

History

The clinical presentation of AIH is usually subtle, while that of AIT can be dramatic, with life-threatening cardiac manifestations without antecedent subclinical biochemical findings. Suspect AIT in a patient who was previously stable while receiving amiodarone but who starts to show signs of cardiac decompensation, tachyarrhythmias, or angina. However, patients may lack cardiac manifestations because of amiodarone's intrinsic effect on the heart, and other signs of hyperthyroidism such as weight loss and fatigue may predominate. Thyrotoxicosis can occur while a patient receives amiodarone and even several months after discontinuation of treatment. Hypothyroidism is rare after the first 18 months of therapy.

  • Symptoms of AIT include the following:
    • Unexplained weight loss
    • Heat intolerance or increased perspiration
    • Profound muscle weakness
    • Unexplained fatigue
    • Emotional lability
    • Frequent stools
    • Oligomenorrhea
    • Anxiety, nervousness, or palpitations
  • Symptoms of AIH include the following:
    • Fatigue
    • Lethargy
    • Cold intolerance
    • Mental sluggishness
    • Weakness
    • Constipation
    • Menorrhagia
    • Dry skin
  • A family history of certain conditions can also be important. Consider the following:
    • Autoimmune disease
    • Thyroid disease
    • Medication history
    • Emigration from iodine-deficient areas
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Physical

The physical signs of thyrotoxicosis or hypothyroidism induced by amiodarone therapy do not differ from those observed in states of thyroid excess or deficiency attributable to other causes.

  • Signs of AIT include tremor, goiter, heart failure, sinus tachycardia, and atrial fibrillation.
  • The presence of proptosis or multinodular or diffuse goiter usually indicates type 1 AIT. A small, often tender, goiter occasionally develops in patients with type 2 AIT.
  • The clinical manifestations of AIH are similar to those of spontaneous hypothyroidism. Patients present with vague symptoms and signs such as fatigue, lethargy, cold intolerance, mental sluggishness, and dry skin. A goiter is found in 20% of patients with hypothyroidism who live in iodine-replete areas, but most of these goiters predate the start of amiodarone treatment. Myxedema coma has also been reported in a patient receiving long-term amiodarone therapy. In patients already receiving levothyroxine replacement therapy, the dose of levothyroxine may need to be increased to offset the amiodarone-induced inhibition of the T4-to-T3 conversion.
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Causes

The risk of developing hypothyroidism or thyrotoxicosis is independent of the daily or cumulative dose of amiodarone. However, some small studies show the contrary. Autoimmune thyroid disease is the principal risk factor for the development of hypothyroidism. High dietary intake and a positive family history of thyroid disease may also be predisposing factors. Females with thyroid peroxidase or thyroglobulin antibodies have a relative risk of 13.5% for the development of hypothyroidism.

A literature review by Zhong et al indicated that new-onset AIH is particularly likely to occur in older women and in regions with a high environmental iodine content. The incidence of AIH in women was reported to be 19.2%, compared with 13.3% in men, with mean age found to correlate positively with the percentage of women. In areas with a high iodine content, the incidence of AIH was 20.3%, compared with 8.7% in regions with a low iodine content.[6]

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Contributor Information and Disclosures
Author

Mini Gopalan, MD Clinical Assistant Professor, Department of Medicine, Texas Tech University; Consulting Physician, Department of Internal Medicine, Midland Community Healthcare Services

Mini Gopalan, MD is a member of the following medical societies: American College of Physicians, American Medical Association, Endocrine Society, Texas Medical Association

Disclosure: Nothing to disclose.

Coauthor(s)

James Burks, MD, FACP, FACE Professor of Medicine, Program Director, Department of Medicine, Texas Tech University Health Sciences Center

James Burks, MD, FACP, FACE is a member of the following medical societies: American Association of Clinical Endocrinologists, American Diabetes Association, Endocrine Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Arthur B Chausmer, MD, PhD, FACP, FACE, FACN, CNS Professor of Medicine (Endocrinology, Adj), Johns Hopkins School of Medicine; Affiliate Research Professor, Bioinformatics and Computational Biology Program, School of Computational Sciences, George Mason University; Principal, C/A Informatics, LLC

Arthur B Chausmer, MD, PhD, FACP, FACE, FACN, CNS is a member of the following medical societies: American Association of Clinical Endocrinologists, American College of Nutrition, American Society for Bone and Mineral Research, International Society for Clinical Densitometry, American College of Endocrinology, American College of Physicians, American College of Physicians-American Society of Internal Medicine, American Medical Informatics Association, Endocrine Society

Disclosure: Nothing to disclose.

Chief Editor

Romesh Khardori, MD, PhD, FACP Professor of Endocrinology, Director of Training Program, Division of Endocrinology, Diabetes and Metabolism, Strelitz Diabetes and Endocrine Disorders Institute, Department of Internal Medicine, Eastern Virginia Medical School

Romesh Khardori, MD, PhD, FACP is a member of the following medical societies: American Association of Clinical Endocrinologists, American College of Physicians, American Diabetes Association, Endocrine Society

Disclosure: Nothing to disclose.

Acknowledgements

Robert A Gabbay, MD, PhD Associate Professor of Medicine, Division of Endocrinology, Diabetes and Metabolism, Laurence M Demers Career Development Professor, Penn State College of Medicine; Director, Diabetes Program, Penn State Milton S Hershey Medical Center; Executive Director, Penn State Institute for Diabetes and Obesity

Robert A Gabbay, MD, PhD is a member of the following medical societies: American Association of Clinical Endocrinologists, American Diabetes Association, and Endocrine Society

Disclosure: Novo Nordisk Honoraria Speaking and teaching; Merck Honoraria Speaking and teaching

References
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