title: Performance Evaluation of the Serum Thyroglobulin Assays With Immunochemiluminometric Assay and Immunoradiometric Assay for Differentiated Thyroid Cancer.
abstract: BACKGROUND
  Measurement of postoperative serum thyroglobulin (Tg) is important for detecting persistent or recurrent differentiated thyroid cancer. We evaluated the analytic performance of the DxI 800 assay (Beckman Coulter, USA) for serum Tg and anti-thyroglobulin antibodies (TgAbs) in comparison with that of the GAMMA-10 assay (Shinjin Medics Inc., Korea) for serum Tg and RIA-MAT 280 assay (Stratec, Germany) for TgAb.
  
  
  METHODS
  We prospectively collected blood samples from 99 patients thyroidectomized for thyroid cancer. The functional sensitivity was investigated in standards and human serum. Precision and linearity were evaluated according to the guidelines of the Clinical and Laboratory Standards Institute. The correlation between the two assays was assessed in samples with different Tg ranges.
  
  
  RESULTS
  The functional sensitivity of the DxI 800 assay for serum Tg was between 0.0313 and 0.0625 ng/mL. The total CV was 3.9-5.6% for serum Tg and 5.3-6.9% for serum TgAb. The coefficient of determination (R²) was 1.0 and 0.99 for serum Tg and TgAb, respectively. The cut-offs for serum TgAb were 4.0 IU/mL (DxI 800) and 60.0 IU/mL (RIA-MAT 280), and the overall agreement was 68.7%. The correlation between the two assays was excellent; the correlation coefficient was 0.99 and 0.88 for serum Tg and TgAb, respectively.
  
  
  CONCLUSIONS
  The DxI 800 is a sensitive assay for serum Tg and TgAb, and the results correlated well with those from the immunoradiometric assays (IRMA). This assay has several advantages over the IRMA and could be considered an alternative test for Tg measurement.
authors.affiliation: Division of Endocrinology & Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yoon Young
authors.initials: YY
authors.lastname: Cho
authors.affiliation: Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Sejong
authors.initials: S
authors.lastname: Chun
authors.affiliation: Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Soo Youn
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Division of Endocrinology & Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Chung
authors.affiliation: Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. nayadoo@hanmail.net.
authors.forename: Hyung Doo
authors.initials: HD
authors.lastname: Park
authors.affiliation: Division of Endocrinology & Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. swkimmd@skku.edu.
authors.forename: Sun Wook
authors.initials: SW
authors.lastname: Kim
mesh_terms: D001323:Autoantibodies / Q000097:blood*; D006801:Humans; D015592:Immunoradiometric Assay; D008163:Luminescent Measurements; D011446:Prospective Studies; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000601:surgery
chemical_list: D001323:Autoantibodies; D011933:Reagent Kits, Diagnostic; C006606:anti-thyroglobulin; D013954:Thyroglobulin
keywords: DxI 800; Evaluation; Immunochemiluminometric assay; Performance; Thyroglobulin