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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