Management of amiodarone-induced thyrotoxicosis in Latin America: an electronic survey.

Objective: To assess diagnostic and therapeutic approaches to amiodarone-induced thyrotoxicosis (AIT) among members of the Latin American Thyroid Society (LATS).

Methods: LATS members responded to an online questionnaire that presented an index case (a 62-year-old man on amiodarone, with thyrotoxic symptoms and a nodular goitre) and a variant (same patient, no goitre).

Results: About 25% of invited members responded to the questionnaire. Most respondents lived in iodine-sufficient areas and observed that amiodarone-induced hypothyroidism (AIH) is more common than AIT. Nearly all assessed TSH, and the most used combination of tests was TSH and free T4 (37%). Thyroid autoimmunity was assessed by about 90%. Interleukin-6 (IL-6) was useful to 80%. Additional tests ordered for the index case were: radioactive iodine uptake (RAIU; 57%), echo-colour Doppler sonography (ECDS; about 50%) and fine-needle aspiration biopsy (FNAB; 44%). For the variant, ECDS and RAIU were judged unhelpful by 16%. Most defined the index case as type I AIT and the variant as type II AIT, but 16% in LATS suggested a mixed form in the index case. As initial treatment, nearly all used thionamides in the index case [with potassium perchlorate (KClO(4)) in one-third], while glucocorticoids were indicated to the variant by 66%. Only about 5% considered amiodarone withdrawal unnecessary. If initial strategy is ineffective in type I AIT, KClO(4) (half) or glucocorticoids (a third) are added; in type II, glucocorticoids are indicated by most. Once euthyroidism is restored, ablative therapy is prescribed by a third of respondents for type I AIT.

Conclusions: There are several points of disagreement among thyroidologists regarding AIT management, mainly in the radiological evaluation and the approach to the already stabilized patient if amiodarone needs to be restarted.