title: Differences in serum thyroglobulin measurements by 3 commercial immunoradiometric assay kits and laboratory standardization using Certified Reference Material 457 (CRM-457).
abstract: BACKGROUND
  Serum thyroglobulin (Tg) is essential in the follow-up of patients with differentiated thyroid carcinoma (DTC). However, interchangeability and standardization between Tg assays have not yet been achieved, even with the development of an international Tg standard (Certified Reference Material 457 [CRM-457]).
  
  
  METHODS
  Serum Tg from 30 DTC patients and serially diluted CRM-457 were measured using 3 different immunoradiometric assays (IRMA-1, IRMA-2, IRMA-3). The intraclass correlation coefficient (ICC) method was used to describe the concordance of each IRMA to CRM-457.
  
  
  RESULTS
  The serum Tg measured by 3 different IRMAs correlated well (r > .85, p < .0001), but clinically relevant discrepancies were found in 13.3% of patients. IRMA-3, which claims to be standardized to CRM-457, showed the best ICC (p(1) = .98) for the CRM-457.
  
  
  CONCLUSIONS
  Hospitals caring for patients with DTC should either set their own cutoffs for IRMAs for Tg based on their patient pools, or adopt IRMAs standardized to CRM-457 and calibrate their laboratory using CRM-457.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Ji In
authors.initials: JI
authors.lastname: Lee
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Joon Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Hee Kyung
authors.initials: HK
authors.lastname: Kim
authors.forename: Hye Won
authors.initials: HW
authors.lastname: Jang
authors.forename: Kyu Yeon
authors.initials: KY
authors.lastname: Hur
authors.forename: Jae Hyeon
authors.initials: JH
authors.lastname: Kim
authors.forename: Kwang-Won
authors.initials: KW
authors.lastname: Kim
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Chung
authors.forename: Sun Wook
authors.initials: SW
authors.lastname: Kim
mesh_terms: D002291:Carcinoma, Papillary / Q000097:blood / Q000473:pathology / Q000601:surgery; D006801:Humans; D015592:Immunoradiometric Assay / Q000379:methods / Q000592:standards*; D008991:Monitoring, Physiologic / Q000379:methods; D011933:Reagent Kits, Diagnostic; D012015:Reference Standards; D015203:Reproducibility of Results; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000473:pathology / Q000601:surgery; D013965:Thyroidectomy / Q000379:methods
chemical_list: D011933:Reagent Kits, Diagnostic; D013954:Thyroglobulin