Amiodarone induced thyroid problems

Q: Amiodarone causes thyroid problems because?

A) It resembles thyroxine

B) It contains high amount of Iodine

C) Both A and B

D) It blocks potassium channels

E) It is idiopathic (cause unknown)

Answer: C

Amiodarone chemically resembles thyroxine, and it binds to the nuclear thyroid receptor which contributes to its toxic effect on thyroid, either amiodarone-induced thyrotoxicosis (AIT) or amiodarone-induced hypothyroidism (AIH). Also, iodine in Amiodarone play significant role in pathology.

There are two main forms of AIT: type 1, a form of iodine-induced hyperthyroidism, and type 2, a drug-induced destructive thyroiditis. However, mixed/indefinite forms also exists.

The most likely mechanism of AIH is an enhanced susceptibility to the inhibitory effect of iodine on thyroid hormone synthesis