High cut-off value of a chimeric TSH receptor (Mc4)-based bioassay can improve prediction of relapse in Graves' disease

Presentation Number: OR50-6
Date of Presentation: June 18th, 2013

Sena Hwang*1, Yongin Cho1, Dong Yeob Shin1 and Eun Jig Lee2
1Yonsei University College of Medicine, Seoul, Korea, Republic of (South), 2Yonsei University College of Medicine, Korea, Republic of (South)

Abstract

Background

There are scarce reports regarding a functional prognostic value of thyroid-stimulating autoantibodies (TSAb) using a thyroid-stimulating hormone receptor chimera (Mc4) in Graves’ disease (GD). The aim of this study was to investigate whether Mc4-TSAb can predict remission/relapse of GD after antithyroid drug (ATD) treatment and to compare with an inhibition assay using a human monoclonal thyroid-stimulating hormone receptor (M22-TRAb) in GD patients.

 Methods

Both M22-TRAb and Mc4-TSAb were measured in 64 GD patients with ATD (22 were newly diagnosed GD and 42 on therapy) before, at the end of treatment, and at the follow up period after ATD discontinuation. They underwent treatment with ATD for proximally 17 months and were followed up for about 8 months (3 – 19 months) after drug discontinuation. We compared between M22-TRAb and Mc4-TSAb values as indices of remission and relapse of GD.

 Results

At the end of ATD treatment, Mc4-TSAb were detected in 72.6% and M22-TRAb in 55.2% patients. Among total, 21 (31.1%) patients were relapsed after three or six months after ATD discontinuation. Among patients with relapse of GD, 8 (38%) patients were seronegative M22-TRAb and 2 (9%) were seronegative Mc4-TSAb at the end of therapy. However, seven (88%) patients with seronegative M22-TRAb were Mc4-TSAb positive and only one patient with seronegative Mc4TSAb was M22-TRAb positive at the same time. Logistic regression analysis showed that the only statistically significant predictor of relapse was Mc4-TSAb level at the end of therapy. Its prognostic value was evaluated by the ROC analysis which indicated the best cut-off of Mc4-TSAb was 245.0% (AUC 0.741, P<0.05) with 75% sensitivity and 78% specificity.

 Conclusion

The Mc4-TSAb could be a clinically useful predictor of relapse of Graves’ disease, and improve its predictive value with higher cut-off of positivity.

 

Nothing to Disclose: SH, YC, DYS, EJL