title: The presence of anti-thyroglobulin (TgAb) and/or anti-thyroperoxidase antibodies (TPOAb) does not exclude the diagnosis of type 2 amiodarone-induced thyrotoxicosis.
abstract: OBJECTIVE
  It is widely accepted that type 2 amiodarone-induced thyrotoxicosis (AIT) generally occurs in patients with a normal thyroid gland without signs of thyroid autoimmunity. However, it is currently unknown if the presence of anti-thyroglobulin (TgAb) and/or anti-thyroperoxidase antibodies (TPOAb) in AIT patients without other signs of an underlying thyroid disease may impair the response to glucocorticoid therapy.
  
  
  METHODS
  We performed a pilot retrospective cohort study with matched-subject design and an equivalence hypothesis, comparing the response to glucocorticoid therapy between 20 AIT patients with a normal thyroid gland, low radioiodine uptake, undetectable TSH receptor antibodies and positive TgAb and/or TPOAb (Ab+ group), and 40 patients with the same features and absent thyroid antibodies (Ab- group).
  
  
  RESULTS
  The mean cure time was 54 ± 68 days in the Ab+ group and 55 ± 49 days in the Ab- group (p = 0.63). The equivalence test revealed an equivalent cure rate after 60, 90 and 180 days (p = 0.67, 0.88 and 0.278, respectively). The occurrence of permanent hypothyroidism was higher in the Ab+ group than in the Ab- group (26.3 vs 5.13 %, p = 0.032).
  
  
  CONCLUSIONS
  The presence of TgAb and/or TPOAb does not affect the response to glucocorticoid therapy, suggesting that the patients with features of destructive form of AIT should be considered as having a type 2 AIT irrespective of the presence of TGAb or TPOAb. These patients have a higher risk of developing hypothyroidism after the resolution of thyrotoxicosis and should be monitored accordingly.
authors.affiliation: Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124, Pisa, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Tomisti
authors.affiliation: Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124, Pisa, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Urbani
authors.affiliation: Unit of Epidemiology and Biostatistics, Institute of Clinical Physiology, National Research Council, 56184, Pisa, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Rossi
authors.affiliation: Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124, Pisa, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Latrofa
authors.affiliation: Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124, Pisa, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Sardella
authors.affiliation: Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124, Pisa, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Manetti
authors.affiliation: Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124, Pisa, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Lupi
authors.affiliation: Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124, Pisa, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Marcocci
authors.affiliation: Endocrine Unit, Department of Clinical and Experimental Medicine, University of Insubria, 21100, Varese, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Bartalena
authors.affiliation: Unit of Epidemiology and Biostatistics, Institute of Clinical Physiology, National Research Council, 56184, Pisa, Italy.
authors.forename: O
authors.initials: O
authors.lastname: Curzio
authors.affiliation: Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124, Pisa, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Martino
authors.affiliation: Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124, Pisa, Italy. fbogazzi@hotmail.com.
authors.forename: F
authors.initials: F
authors.lastname: Bogazzi
mesh_terms: D000328:Adult; D000638:Amiodarone / Q000009:adverse effects*; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D001324:Autoantigens / Q000276:immunology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007453:Iodide Peroxidase / Q000276:immunology*; D033862:Iron-Binding Proteins / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011379:Prognosis; D012189:Retrospective Studies; D013971:Thyrotoxicosis / Q000097:blood / Q000139:chemically induced / Q000175:diagnosis* / Q000276:immunology; D014665:Vasodilator Agents / Q000009:adverse effects*
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D033862:Iron-Binding Proteins; D014665:Vasodilator Agents; C006606:anti-thyroglobulin; C056658:TPO protein, human; D007453:Iodide Peroxidase; D000638:Amiodarone
keywords: Amiodarone; Antibodies; Hyperthyroidism; Thyroid; Thyrotoxicosis