Significance of thyrotrophic receptor antibody(TRAb) in clinical diagnosis of Graves' disease

Objective To investigate the clinical significance of serum thyrotrophic receptor antibody(TRAb) in the diagnosis of Graves' disease(GD).Methods Serum level of TRAb was measured with enzyme-linked immunosorbent assay(ELISA) in 298 untreated patients with GD,212 cases with hypothyroidism,47 cases with subacute thyroiditis,161 cases with thyroid nodule and 73 health controls.ROC curve with SPSS 13.0 was drawn according to the data from patients with GD and subacute thyroiditis.Results The mean value of serum TRAb was significantly higher in Graves' patients than in patients with other thyroid diseases.The positive rates of TRAb was highest in GD patients(93.3%),followed by the patients with subacute thyroiditis and hypothyroidism(14.9% and 11.3%),and the lowest in the patients with thyoid nodule(1.2%).Serum levels of TRAb in untreated GD showed various titers,and TRAb30U/L was more commonly found(38.3%).ROC analysis showed that diagnostic code on TRAb for subacute thyroiditis and GD patients was 1.495U/L(93.5% sensitivity and 85.1% specificity),and the doubtable value interval of 1.11U/L to 13.65U/L was determined.Finally,there was a positive correlation between the serum titer of TRAb and TPOAb(P0.01).Conclusion TRAb measured by ELISA is a stimulating antibody,and may be used in the differential diagnosis of GD and subacute thyroiditis.