Objective To explore the applicability of 3rd generation thyroid stimulating hormone receptor antibody (TRAb) assay (Elecsys) in clinical differentiation of thyrotoxicosis.
Methods 154 subjects with untreated thyrotoxicosis, who were admitted to Huashan Hospital between January 2016 and May 2018 were retrospectively selected. Thyroid function, TRAb, radioactive iodine uptake (RAIU), and mean peak systolic velocity of superior thyroid artery (STA-PSV) were detected. Receiver operating characteristic (ROC) curves were plotted to compare the value of the third generation TRAb and STA-PSV in the differential diagnosis of Graves'disease (GD) and destructive thyroiditis (DT).
Results Of the 154 subjects with untreated thyrotoxicosis enrolled, 111 (72.0%) were female, their mean age were 38.42 years. Totally, 117 (76.0%) were diagnosed as GD. The area under the ROC curve for TRAb in the differential diagnosis of thyrotoxicosis was 0.984 (95%CI 0.967-1.000), superior to that of STA-PSV (AUC 0.903, 95%CI 0.839-0.967). The best cutoff point of TRAb was 1.7 U/L, the sensitivity and specificity in distinguishing GD from DT were 94.8% and 94.3%, respectively. If TRAb cutoff point was set 3.6 U/L, its specificity and postive predictive value in GD differentiation reached 100%. There are 5 TRAb negative (< 1.7 U/L) GD cases, all of whom have significantly elevated STA-PSV.
Conclusions The 3rd generation TRAb assay (Elecsys) is sensitive and specific in the differential diagnosis of thyrotoxicosis.
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