2-B-P-063 〇長田 佳子¹、遠藤 佑輔²、市原 克則¹、澤野 達哉¹、プリヨノ アグン¹、三明 淳一朗¹、今村 武史¹ Nagata Keiko¹, Yusuke Endo², Yoshinori Ichihara¹, Tatsuya Sawano¹, Agung Kurniawan Priyono¹, Junichiro Miake¹, Takeshi Imamura^{1 1}鳥取大・医・薬理学・薬物療法学、²鳥取大・研究推進機構 ¹Division of Pharmacology, Faculty of Medicine, Tottori University, ²Organization for Research Initiative and Promotion, Tottori University Objective
Thyrotropin receptor antibodies (TRAbs) are causative antibodies of Graves' disease. TRAbs are heterogeneous antibodies containing stimulating type (thyroid stimulating antibody: TSAb), blocking type, neutral type, and they could be classified into immunoglobulin isotype (TRAb-IgG and TRAb-IgM). Although the currently used methods are not suitable to measure TRAb-IgM, it may be the important antibody produced prior to TRAb-IgG. In the present study, we measured TRAb-isotype and calculated TRAb-IgM/TRAb-IgG (MG ratio), and report the possibility that MG ratio may be a predictor of clinical state of Graves' disease
Methods
We prepared total of 50 serial samples from 14 patients of Graves' disease (7 hyperthyroidism, 8 hypothyroidism, and 35 euthyroidism), and single samples from 50 patients of Graves' disease and 10 healthy subjects. TRAb-IgG, TRAb-IgM, and MG ratio of these samples were measured by ELISA system.
Results & Discussion
MG ratio could separate euthyroid from hyper or hypothyroidism (Cut off: 9.532, AUC: 0.947, 95% confidence interval: 0.889-1). Both TRAb-IgG and TRAb-IgM could diagnose Graves' disease with good positive or negative percent agreement with conventional RRA.
In some cases, increases of MG ratio were observed before severe hypothyroidism suggested the appearance of blocking TRAb.
Conclusions
MG ratio could detect exacerbation of Graves' disease, and TRAb-IgG and TRAb-IgM can be used for conventional TRAb. TRAb isotype and MG ratio may become necessary to know pathophysiology of Graves' disease.