Table 2.

Comparison between AIT type 1 versus AIT type 2

Criteria	AIT 1	AIT 2
Mechanism	Excessive hormone production (true hyperthyroidism)	Destructive thyroiditis
Underlying thyroid abnormality	Yes	Usually no
Colour-flow Doppler ultrasound	Increased vascularity	No hypervascularity
Thyroid radio-iodine uptake	Decreased/normal/increased	Decreased
Thyroid autoantibodies	Present if AIT is due to Graves’ disease	Usually absent
Onset time after starting amiodarone	Short (median 3 months)	Long (median 30 months)
Spontaneous remission	No	Possible
Subsequent hypothyroidism	No	Possible
First-line medical treatment	Thionamides	Oral glucocorticoids
Subsequent definitive thyroid treatment	Generally yes	No

Adapted with permission from Bartalena L, Bogazzi F, Chiovato L, et al. 2018 European Thyroid Association (ETA) guidelines for the management of amiodarone-associated thyroid dysfunction. Eur Thyroid J 2018;7:55–66. Copyright 2018 S. Karger AG, Basel.¹¹

AIT, amiodarone-induced thyrotoxicosis.