Amiodarone-induced thyrotoxicosis: a review.
BACKGROUND
Amiodarone-induced thyrotoxicosis (AIT) develops in 3% of amiodarone-treated patients in North America. AIT is classified as type 1 or type 2. Type 1 AIT occurs in patients with underlying thyroid pathology such as autonomous nodular goiter or Graves' disease. Type 2 AIT is a result of amiodarone causing a subacute thyroiditis with release of preformed thyroid hormones into the circulation.


OBJECTIVE
To review the literature and present an overview of the differentiation between and management of type 1 and type 2 AIT.


METHODS
PubMed, the Cumulative Index to Nursing and Allied Health Literature and Medscape searches of all available English language articles from 1983 to 2006 were performed. Search terms included 'amiodarone -induced thyrotoxicosis', 'complications', 'management', 'treatment' and 'colour flow Dopper sonography'.


RESULTS
There is evidence to suggest that to differentiate between type 1 and type 2 AIT, a careful history and physical examination should be performed to identify pre-existing thyroid disease. An iodine-131 uptake test and colour flow Doppler sonography should be performed. Patients with type 2 AIT should receive a trial of glucocorticoids, whereas those with type 1 should receive antithyroid therapy. For patients in whom the mechanism of the thyrotoxicosis is unclear, a combination of prednisone and antithyroid therapy may be considered.
Tsang
Wendy
W
University of Toronto, Toronto, Ontario.
Houlden
Robyn L
RL
D000638:Amiodarone / Q000009:adverse effects*; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects*; D006044:Goiter, Nodular / Q000150:complications; D006111:Graves Disease / Q000150:complications; D006801:Humans; D013968:Thyroiditis, Subacute / Q000150:complications; D013971:Thyrotoxicosis / Q000139:chemically induced* / Q000145:classification / Q000175:diagnosis / Q000209:etiology; D014665:Vasodilator Agents / Q000009:adverse effects*
D000889:Anti-Arrhythmia Agents; D014665:Vasodilator Agents; D000638:Amiodarone