title: Amiodarone-induced thyrotoxicosis late after amiodarone withdrawal.
abstract: BACKGROUND
  Amiodarone-induced thyrotoxicosis (AIT) may develop long after amiodarone withdrawal. This study sought to determine the incidence and clinical characteristics of AIT after amiodarone withdrawal.
  
  
  RESULTS
  The incidence and clinical characteristics of AIT were examined retrospectively in 71 patients (51 males, mean age 65±13 years) whose amiodarone therapy had been discontinued after at least 1 month of administration. Five (7%) patients developed AIT late after amiodarone withdrawal (11±3 months): 2 patients exhibited exacerbation of heart failure by atrial fibrillation, 2 developed dyspnea on exertion, and 1 patient was asymptomatic. The patients who developed AIT had a high incidence of amiodarone-induced hypothyroidism during amiodarone therapy (100 vs. 24%, P=0.002), had received amiodarone therapy for longer (76±86 months vs. 16±22 months, P<0.001), with a larger cumulative dose (271.1±268.5 g vs. 63.4±86.5 g, P<0.001) compared with those who did not. In all 5 patients, AIT resolved spontaneously within 5 months without the use of steroids.
  
  
  CONCLUSIONS
  Occurrence of amiodarone-induced hypothyroidism during amiodarone therapy and long duration of therapy may be cautionary markers of late AIT.
authors.affiliation: Department of Cardiovascular Medicine, Tokyo Medical and Dental University.
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Yagishita
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Hachiya
authors.forename: Mihoko
authors.initials: M
authors.lastname: Kawabata
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Koji
authors.initials: K
authors.lastname: Sugiyama
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Sasano
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Isobe
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hirao
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000638:Amiodarone / Q000008:administration & dosage / Q000009:adverse effects*; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000009:adverse effects*; D001281:Atrial Fibrillation / Q000139:chemically induced / Q000453:epidemiology; D004417:Dyspnea / Q000139:chemically induced / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013971:Thyrotoxicosis / Q000139:chemically induced* / Q000453:epidemiology; D013997:Time Factors
chemical_list: D000889:Anti-Arrhythmia Agents; D000638:Amiodarone