Stimulating TSH receptor autoantibodies immunoassay: analytical evaluation and clinical performance in Graves’ disease

C. Autilio, R. Morelli, P. Locantore, A. Pontecorvi, C. Zuppi, C. Carrozza

Research output: Contribution to journalArticle

Abstract

Background: Thyroid-stimulating hormone (TSH) receptor (TSHR) autoantibodies (TRAbs) are a heterogeneous group of antibodies (Abs) with different functionalities. Among all TRAbs, only the stimulating ones (S-TRAbs) are considered as the pathogenetic marker of Graves’ disease (GD). To date, the methods available for TRAbs testing are based on immunoassays (IMAs) which detect total serum TRAbs or bioassays which are not suitable in clinical practice, even though they discern Abs functionality. The aim of our work was to evaluate the analytical and clinical performance of a very recent IMA (Immulite TSI method), supposed to test only the serum concentration of S-TRAbs, in comparison with a current method for total TRAbs (Roche/Elecsys IMA). Methods: We evaluated serum samples of 145 subjects: 46 with untreated (GD), 36 with chronic autoimmune thyroiditis, 3 with atrophic thyroiditis, 10 with multinodular non-toxic goiter and 50 healthy subjects. Results: The method showed an optimal analytical sensitivity and high precision levels (LoB: 0.04 UI/L, LoD:0.07 UI/L, LoQ:0.14 UI/L, intra-assay CV: 4.2–5.9%, inter-assay: 4.5–7.2%). By receiver operating characteristics curve analysis, we obtained a value of 0.57 (sensitivity: 98.0%, specificity: 99.9%) as the best cut-off to distinguish GD, apart from four cases. Passing Bablok regression and Bland Altman analysis pointed out a good correlation and agreement with Roche method (R2= 0.98, slope = 1.03, bias = −2.70). Conclusions: The new method presents very promising analytical characteristics and could be adopted in clinical practice for GD diagnosis. Moreover, the test allows to accurately detect very low values of analyte with a further clinical utility in detecting earlier possible relapses.

Original languageEnglish
Pages (from-to)172-177
Number of pages6
JournalAnnals of Clinical Biochemistry
Volume55
Issue number1
DOIs
Publication statusPublished - Jan 1 2018

Keywords

  • Graves’ disease
  • hyperthyroidism
  • S-TRAbs

ASJC Scopus subject areas

  • Clinical Biochemistry

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