What are the risk factors for amiodarone-associated thyroid dysfunction?

Updated: Aug 28, 2020
  • Author: Mini Gopalan, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Answer

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 Japanese study, by Kinoshita et al, indicated that in patients receiving amiodarone, the presence of dilated cardiomyopathy and cardiac sarcoidosis are risk factors for amiodarone-induced hyperthyroidism, while higher baseline TSH levels and lower baseline free thyroxine levels are predictors for amiodarone-induced hypothyroidism. The investigators also stated that because the TSH and free thyroxine levels are apparent risk factors, subclinical hypothyroidism may be a predictor for amiodarone-induced hypothyroidism. [10]

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. [11]


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