Endocrine Abstracts

Introduction: Thyroglobulin plays a vital role in the follow-up of patients with differentiated thyroid carcinoma (DTC) after thyroidectomy combined with radioiodine (RAI) ablation. As to preablative stimulated thyroglobulin (ps-Tg), though several studies have manifested its potential in identifying distant metastatic DTC (DM-DTC), it remains unclear whether a single ps-Tg is sufficient for predicting DM-DTC. This retrospective study was aimed to evaluate the utility of serial ps-Tg measurements in identifying DM-DTC.

Methods: A series of ps-Tg, thyroid-stimulating hormone (TSH) and anti-Tg antibody (TgAb) was measured in 317 consecutive DTC patients before RAI administration, among which data collected at the first time were marked as Tg1, TSH1 and TgAb1, respectively, while as Tg2, TSH2 and TgAb2 at the last time. Patients were divided into two groups as M1 (n=72) and M0 (n=245) according to the presence of DM or not. Parameters derived from the change in ps-Tg including ΔTg (Tg2-Tg1), ΔTg′ (Tg2/TSH2-Tg1/TSH1) and ΔTg/ΔTSH (ΔTg/(TSH2-TSH1)) were calculated and further combined with an actual or corrected value of ps-Tg (Tg1, Tg2, Tg1/TSH1 or Tg2/TSH2). All the independent and combined parameters were tested for diagnostic performance in identifying DM-DTC.

Results: Higher Tg1, Tg2, Tg1/TSH1, Tg2/TSH2 and wider amplitudes of ΔTg, ΔTg′, ΔTg/ΔTSH were observed in M1 (all P<0.01). Tg2 and Tg2/TSH2, with corresponding areas under ROC curves (AUC) of both 0.947, were more accurate than Tg1 and Tg1/TSH1. ΔTg/ΔTSH manifested the highest accuracy (88.64%) and specificity (90.20%) among the three parameters of preablative changes, with a diagnostic range of −0.40~0.41 ng/μIU. Moreover, the diagnostic performance was further improved with a larger AUC (0.951) by combing ΔTg/ΔTSH with Tg2/TSH2.

Conclusions: Serial ps-Tg measurements hold incremental value in identifying DM-DTC. ΔTg/ΔTSH in conjunction with Tg2/TSH2 is a favorable indicator for DM-DTC as well as a feasible approach to assist in preablative assessment and decision-making.

Disclosure: This work was supported by the Ministry of Health Industry Special Scientific Research Projects of China (201202012) and the National Natural Science Foundation of China (30970850).