Amiodarone induced thyroid dysfunction – Medicine MCQ

Wrong statement about amiodarone induced thyroid dysfunction:
A) Hypothyroidism occurs in iodine sufficient areas
B) Hyperthyroidism occurs in iodine deficient areas
C) Amiodarone can cause destructive thyroiditis
D) Amiodarone increases 5-deiodinase activity

Correct answer: D) Amiodarone increases 5-deiodinase activity

amiodaroneStructure of amiodarone (note the iodine atoms attached to the benzene ring in the middle)
Amiodarone induced thyroid dysfunction

Amiodarone is a commonly used class III antiarrhythmic drug.
It has a high iodine content.
It can produce hypothyroidism in patients from iodine sufficient areas and hyperthyroidism in those from iodine deficient areas.
It reduces 5-deiodinase activity and thereby decreases the conversion of T4 to T3.
There is decreased generation of T3 and reduced clearance of rT3 (reverse T3), leading to accumulation of rT3.
Destructive thyroiditis is the result of direct toxic effect of amiodarone and its metabolite on thyroid follicular cells.

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