title: Relevance of TSH-receptor antibody levels in predicting disease course in Graves' orbitopathy: comparison of the third-generation TBII assay and Mc4-TSI bioassay.
abstract: OBJECTIVE
  To investigate if TSH-receptor antibody (TRAb) levels measured in early Graves' orbitopathy (GO) stages are predictive of clinical disease course beyond 1 year after initial GO diagnosis and to compare performance of two newly developed TRAb assays (third-generation thyrotropin-binding inhibitor immunoglobulin (TBII) assay vs Mc4-thyroid-stimulating immunoglobulin (TSI) bioassay) in predicting disease course.
  
  
  METHODS
  Newly diagnosed, untreated GO patients whose duration of ocular symptoms was less than 6 months were included. One year after initial diagnosis, all patients were classified as presenting either a mild (Group 1) or severe course (Group 2) according to their clinical manifestations. The measurements of two TRAb assays at initial GO diagnosis were used for analysis.
  
  
  RESULTS
  Data from 112 patients were available for analysis. Seventy-three patients (65.2%) were designated as Group 1, and 39 patients (34.8%) as Group 2. Patients with higher initial TRAb levels demonstrated a higher risk of severe disease course upon multiple regression analysis (P<0.01). The cutoff values for the prediction of severe course of the third-generation TBII and Mc4-TSI assays were 10.67 IU/l and 555.10%, respectively, with assay specificities of 84.9 and 89.0%. The TBII assay predictive power (area under the curve (AUC)=0.817; 95% confidence interval (CI) =0.732-0.902) was equivalent to the TSI bioassay (AUC=0.868, 95% CI=0.803-0.934) (P=0.203).
  
  
  CONCLUSIONS
  The predictive power of the third-generation TBII assay and Mc4-TSI bioassay are similarly strong. Measurement of TRAb using either third-generation TBII or Mc4-TSI in early GO periods would provide important prognostic information on future GO course.
authors.affiliation: Department of Ophthalmology, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea.
authors.forename: S Y
authors.initials: SY
authors.lastname: Jang
authors.forename: D Y
authors.initials: DY
authors.lastname: Shin
authors.forename: E J
authors.initials: EJ
authors.lastname: Lee
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee
authors.forename: J S
authors.initials: JS
authors.lastname: Yoon
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D001681:Biological Assay / Q000379:methods*; D005260:Female; D049970:Graves Ophthalmopathy / Q000097:blood / Q000276:immunology*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011989:Receptors, Thyrotropin / Q000097:blood / Q000276:immunology*; D012044:Regression Analysis; D012189:Retrospective Studies
chemical_list: D001323:Autoantibodies; D011989:Receptors, Thyrotropin