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.