title: Concordance between thyroglobulin antibody assays.
abstract: BACKGROUND
  Antithyroglobulin antibodies are a prevalent cause of interference in serum thyroglobulin immunoassays. Current guidelines recommend that antithyroglobulin antibodies should be measured concurrently with thyroglobulin when monitoring thyroid cancer patients post-thyroidectomy. However, the concordance between different antithyroglobulin assays has been questioned despite the availability of an international thyroglobulin antibody Reference Preparation.
  
  
  METHODS
  Four antithyroglobulin assays currently in use in UK laboratories (Siemens Immulite(®), Brahms GmbH, PerkinElmer AutoDELFIA and Siemens ADVIA Centaur(®)) were compared in a cohort of 145 thyroid cancer patients.
  
  
  RESULTS
  Using reference data provided by the kit manufacturer, concordance between the assays was 74%. Adjusting the cut-offs to maximize agreement increased concordance to 90%. Recovery of exogenous thyroglobulin using the Brahms Tg-plus immunoradiometric assay was neither a specific nor a sensitive test for the presence of a positive antibody result by any assay.
  
  
  CONCLUSIONS
  Despite the availability of an international reference preparation, current antithyroglobulin assays show unacceptable variance.
authors.affiliation: Department of Clinical Biochemistry, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Taylor
authors.forename: Damon
authors.initials: D
authors.lastname: Parkington
authors.forename: Sonia
authors.initials: S
authors.lastname: Bradbury
authors.forename: Helen L
authors.initials: HL
authors.lastname: Simpson
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Jefferies
authors.forename: David J
authors.initials: DJ
authors.lastname: Halsall
mesh_terms: D001323:Autoantibodies / Q000097:blood*; D015331:Cohort Studies; D006801:Humans; D007118:Immunoassay / Q000592:standards; D012015:Reference Standards; D013954:Thyroglobulin / Q000097:blood* / Q000276:immunology*; D013964:Thyroid Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000601:surgery
chemical_list: D001323:Autoantibodies; C006606:anti-thyroglobulin; D013954:Thyroglobulin