title: Treatment of amiodarone-induced thyrotoxicosis, a difficult challenge: results of a prospective study.
abstract: Amiodarone-induced thyrotoxicosis (AIT) occurs in both abnormal (type I) and apparently normal (type II) thyroid glands due to iodine-induced excessive thyroid hormone synthesis in patients with nodular goiter or latent Graves' disease (type I) or to a thyroid-destructive process caused by amiodarone or iodine (type II). Twenty-four consecutive AIT patients, 12 type I and 12 type II, were evaluated prospectively. Sex, age, severity of thyrotoxicosis, and cumulative amiodarone dose were similar. Type II patients had higher serum interleukin-6 (IL-6; median, 440 vs. 173 fmol/L; P < 0.001), but lower serum thyroglobulin levels. Several weeks of thionamide therapy in eight type II or prolonged glucocorticoid administration in two type I patients had previously failed to control hyperthyroidism. Type II patients were given prednisone (initial dose, 40 mg/day) for 3 months and achieved normal free T3 and IL-6 after an average of 8 and 6 days, respectively. Exacerbation of thyrotoxicosis with increased serum IL-6 values, observed in 4 patients while tapering steroid, was promptly corrected by increasing it. Type I patients, given methimazole (30 mg/day) and potassium perchlorate (1 g/day), achieved normal free T3 and IL-6 concentrations after an average of 4 weeks. Exacerbation of thyrotoxicosis with markedly increased IL-6 was controlled by prednisone in 3 of 4 cases. Distinction of different forms of AIT is essential for its successful management. Type II AIT should be treated with glucocorticoids; type I AIT should be treated with methimazole and potassium perchlorate. Exacerbation of thyrotoxicosis, which may occur in both forms and is probably related to destructive processes, should be controlled by the addition/increase in glucocorticoids.
authors.affiliation: Istituto di Endocrinologia, University of Pisa, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Bartalena
authors.forename: S
authors.initials: S
authors.lastname: Brogioni
authors.forename: L
authors.initials: L
authors.lastname: Grasso
authors.forename: F
authors.initials: F
authors.lastname: Bogazzi
authors.forename: A
authors.initials: A
authors.lastname: Burelli
authors.forename: E
authors.initials: E
authors.lastname: Martino
mesh_terms: D000328:Adult; D000368:Aged; D000638:Amiodarone / Q000009:adverse effects*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008713:Methimazole / Q000627:therapeutic use; D008875:Middle Aged; D010472:Perchlorates / Q000627:therapeutic use; D017680:Potassium Compounds / Q000627:therapeutic use; D011241:Prednisone / Q000627:therapeutic use; D011446:Prospective Studies; D013971:Thyrotoxicosis / Q000097:blood / Q000139:chemically induced* / Q000145:classification; D014284:Triiodothyronine / Q000097:blood
chemical_list: D015850:Interleukin-6; D010472:Perchlorates; D017680:Potassium Compounds; D014284:Triiodothyronine; C009006:potassium perchlorate; D008713:Methimazole; D000638:Amiodarone; D011241:Prednisone