Renato Tozzoli1, Graziano Kodermaz1, Danilo Villalta2, Marcello Bagnasco3, Giampaola Pesce3, Nicola Bizzaro4. 1. Clinical Pathology Laboratory, Beata Vergine delle Grazie Hospital, Latisana, Italy. 2. Allergology and Immunology Unit, S. Maria degli Angeli Hospital, Pordenone, Italy. 3. Department of Internal Medicine, S. Martino Hospital, University of Genua, Genua, Italy. 4. Clinical Pathology Laboratory, S. Antonio Hospital, Tolmezzo, Italy.
Abstract
PURPOSE: Specific autoantibodies acting as TSH receptor agonists (TRAb) are responsible for Graves' disease (GD). In the last 30 years three generations of assay methods for the detection of TRAb have become available. The aim of this multicentre study was to evaluate the analytical sensitivity, precision and diagnostic accuracy of TRAb measurement using a new automated assay in comparison with a second-generation standard method. METHODS: Serum samples from patients with GD (n=82), autoimmune thyroiditis (AIT, n=57) or hyperthyroidism (HT, n=292), from 106 healthy subjects and from 57 patients with infectious diseases were analysed using a third-generation TRAb immunoassay (anti-TSHR, RAD 120; Radim, Italy) based on the human monoclonal TSH receptor antibody M22. RESULTS: Using a cut-off value of 1.25 mIU/l, established by ROC curve analysis, 80/82 GD patients (97.5%), 68/292 HT patients (23.2%), and 6/57 AIT patients (10.5%) were TRAb-positive with the M22-based automated assay. The percentages of TRAb positivity were lower in the same patients when the measurements were done with the second-generation method (95.1%, 18.9%, 7.0%, respectively). CONCLUSION: The M22-based automated immunoassay shows high functional sensitivity (0.4 mIU/l) and high diagnostic specificity, is more sensitive than the standard second-generation method and is less time-consuming and labourintensive, and is therefore the up-to-date technology for TRAb detection in clinical practice.
PURPOSE: Specific autoantibodies acting as TSH receptor agonists (TRAb) are responsible for Graves' disease (GD). In the last 30 years three generations of assay methods for the detection of TRAb have become available. The aim of this multicentre study was to evaluate the analytical sensitivity, precision and diagnostic accuracy of TRAb measurement using a new automated assay in comparison with a second-generation standard method. METHODS: Serum samples from patients with GD (n=82), autoimmune thyroiditis (AIT, n=57) or hyperthyroidism (HT, n=292), from 106 healthy subjects and from 57 patients with infectious diseases were analysed using a third-generation TRAb immunoassay (anti-TSHR, RAD 120; Radim, Italy) based on the human monoclonal TSH receptor antibody M22. RESULTS: Using a cut-off value of 1.25 mIU/l, established by ROC curve analysis, 80/82 GDpatients (97.5%), 68/292 HTpatients (23.2%), and 6/57 AIT patients (10.5%) were TRAb-positive with the M22-based automated assay. The percentages of TRAb positivity were lower in the same patients when the measurements were done with the second-generation method (95.1%, 18.9%, 7.0%, respectively). CONCLUSION: The M22-based automated immunoassay shows high functional sensitivity (0.4 mIU/l) and high diagnostic specificity, is more sensitive than the standard second-generation method and is less time-consuming and labourintensive, and is therefore the up-to-date technology for TRAb detection in clinical practice.
Authors: J Sanders; J Jeffreys; H Depraetere; M Evans; T Richards; A Kiddie; K Brereton; L D K E Premawardhana; D Y Chirgadze; R Núñez Miguel; T L Blundell; J Furmaniak; B Rees Smith Journal: Thyroid Date: 2004-08 Impact factor: 6.568