MOFFITT ENDOCRINE REPORT PEARLS 9/14/16: Amiodarone-Induced Thyroid Dysfunction!

Thanks to Annie and Jeff for presenting two great endocrine cases this morning exploring the parathyroid and thyroid pathways! Here are some learning points from one of our cases:


Top Pearl:

*There are two types of amiodarone-induced hyperthyroidism: 1) Excess iodine causing increased thyroid hormone synthesis and 2) Autoimmune-mediated thyroid destruction causing increased thyroid hormone release.



  • Missed hyperthyroidism (now burned out thyroid gland)
  • Wolff-Chaikoff effect: iodine temporarily inhibits thyroid hormone biosynthesis, “escape” from this effect after 2-4 weeks of iodine exposure
  • Amiodarone-induced hypothyroidism more common in pts with pre-existing autoimmune hypothyroidism

Tx: Continue amiodarone and give thyroid replacement (although hypothyroidism often resolves if amiodarone is stopped for other reasons)

Hyperthyroidism aka amiodarone-induced thyrotoxicosis (AIT):

  • Type 1: increased synthesis of thyroid hormone (from increased iodine)
  • Type 2: excess release due to destructive thyroiditis (autoimmune)

Doppler ultrasound is the best way to distinguish between type 1 and type 2 AIT

Tx: Discontinue amiodarone unless necessary and effective for life-threatening arrhythmia.

  • For type 1 AIT, control hyperthyroidism before d/c amio, otherwise could get worse transiently.
  • For type 2 AIT, give steroids whether or not amio is discontinued.




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