Amiodarone and thyroid.
Assessment of TSH and TPO-Ab before starting amiodarone (AM) treatment is recommended. The usefulness of periodic TSH measurement every 6 months during AM treatment is limited by the often sudden explosive onset of AIT, and the spontaneous return of a suppressed TSH to normal values in half of the cases. AM-induced hypothyroidism develops rather early after starting treatment, preferentially in iodine-sufficient areas and in females with TPO-Ab; it is due to failure to escape from the Wolff-Chaikoff effect, resulting in preserved radioiodine uptake. AM-induced thyrotoxicosis (AIT) occurs at any time during treatment, preferentially in iodine-deficient regions and in males. AIT can be classified in type 1 (iodide-induced thyrotoxicosis, best treated by potassium perchlorate in combination with thionamides and discontinuation of AM) and type 2 (destructive thyrotoxicosis, best treated by prednisone; discontinuation of AM may not be necessary). AIT is associated with a higher rate of major adverse cardiovascular events (especially of ventricular arrhythmias). Uncertainty continues to exist with respect to the feasibility of continuation of AM despite AIT, the appropriate methods to distinguish between AIT type 1 and 2 as well as the advantages of AIT classification into subtypes in view of possible mixed cases, and the best policy when AM needs to be restarted.
Eskes
Silvia A
SA
Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, The Netherlands.
Wiersinga
Wilmar M
WM
D000638:Amiodarone / Q000009:adverse effects* / Q000031:analogs & derivatives / Q000378:metabolism / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects* / Q000627:therapeutic use; D000077764:Dronedarone; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000139:chemically induced; D008297:Male; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000188:drug therapy; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000187:drug effects*; D013971:Thyrotoxicosis / Q000139:chemically induced / Q000188:drug therapy; D013972:Thyrotropin / Q000276:immunology
D000889:Anti-Arrhythmia Agents; D013972:Thyrotropin; D000077764:Dronedarone; D000638:Amiodarone