Table 2 Amiodarone induced thyrotoxicosis (AIT).

	AIT1	AIT2
Thyroid	Goitre +	Normal
Ultrasound imaging	MNG/diffuse goitre	Normal
Colour flow Doppler scan	Normal or increased flow	Decreased flow
Thyroid antibodies	Absent/present	Absent generally
Interleukin 6	Normal or high	Very high
RAI uptake	Low or normal	Very low/absent
Preferred treatment	Carbimazole/PTU Potassium perchlorate	Glucocorticoids

AIT—more common in iodine deficient (12%) compared with sufficient areas (2%). AIT1 results from iodine excess and AIT2 is a destructive thyroiditis. Clinically a combination of AIT1 and 2 often occurs. AIH—amiodarone induced hypothyroidism is more common in iodine replete (13%) compared with iodine deficient areas (6%). Hormone synthesis is reduced particularly in TPOAb positive patients.