title: The prevalence of autoantibodies to: myosin, troponin, tropomyosin and myoglobin in patients with circulating triiodothyronine and thyroxine autoantibodies (THAA).
abstract: OBJECTIVE
  Anti-thyroglobulin, anti-thyroid-peroxidase and anti-TSH receptor antibodies have been observed with high frequency in autoimmune thyroid diseases. Thyroid hormone auto-antibodies (THAA): anti-thyroxine (T4) and anti-triiodothyronine (T3), conversely, have been reported rarely. In both hyperthyroidism and hypothyroidism, patients suffer from muscle weakness and function disorders. The aim of our study was the evaluation of the occurrence rate of autoantibodies targeting muscle proteins in a group of 24 patients with circulating anti-T3 and/or anti-T4 autoantibodies. The control group consisted of 41 healthy blood donors.
  
  
  METHODS
  In polyethylene tubes coated with muscle antigens: actin, myosin, myoglobin, troponin and tropomyosin solid-phase radioimmunoassay was performed to detect autoantibodies. A reaction with 125I-labelled staphylococcus protein A was used for the detection of antibodies bound to the antigens on the tubes.
  
  
  RESULTS
  We found a high occurrence of antibodies to muscle proteins in patients with THAA. Anti-myoglobin autoantibodies were most frequent (54.2% of subjects), the binding index values was very high and exceeded normal values two to four fold. Anti-myosin autoantibodies were detected in 50% of subjects; anti-troponin autoantibodies in 33.3%, and anti-tropomyosin autoantibody in 3 patients (12.5%). Differences between the patients and the controls were statistically significant. The antibody binding index to actin was low and statistically insignificant.
  
  
  CONCLUSIONS
  Our study indicates that muscle protein antibodies, especially to myoglobin, myosin and troponin, are very frequently present in patients with autoimmune thyroid disease and circulating anti-T3 and anti-T4 autoantibodies, as well as in most cases of chronic thyroiditis with clinical symptoms of hypothyroidisms.
authors.affiliation: Department of Endocrinology, Metabolism and Internal Medicine, University of Medical Sciences, Poznan, Poland. mruchala@ump.edu.pl
authors.forename: Marek
authors.initials: M
authors.lastname: Ruchala
authors.forename: Jerzy
authors.initials: J
authors.lastname: Kosowicz
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Baumann-Antczak
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Skiba
authors.forename: Hanna
authors.initials: H
authors.lastname: Zamyslowska
authors.forename: Jerzy
authors.initials: J
authors.lastname: Sowinski
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D001327:Autoimmune Diseases / Q000276:immunology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009211:Myoglobin / Q000276:immunology*; D009218:Myosins / Q000276:immunology*; D013959:Thyroid Diseases / Q000276:immunology*; D013974:Thyroxine / Q000276:immunology*; D014284:Triiodothyronine / Q000276:immunology*; D014335:Tropomyosin / Q000276:immunology*; D014336:Troponin / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D009211:Myoglobin; D014335:Tropomyosin; D014336:Troponin; D014284:Triiodothyronine; D009218:Myosins; D013974:Thyroxine