Monitoring differentiated thyroid cancer patients with negative serum thyroglobulin. Diagnostic implication of TSH-stimulated antithyroglobulin antibody.

Abstract Serum antithyroglobulin antibody (TgAb) has been reported as a surrogate marker for differentiated thyroid cancer (DTC) in some conditions. We investigated changes in serum TgAb levels after stimulation with thyroid-stimulating hormone (TSH) and the clinical implications for monitoring DTC. We retrospectively enrolled 53 DTC patients who had undergone total thyroidectomy and were negative for serum Tg and positive for TgAb. Patients underwent high-dose radioactive iodine treatment, and serum TgAb was measured before (TgAbBAS) and after TSH stimulation (TgAbSTIM). TgAb was followed up 6 to 12 months later (TgAbF/U). The change in TgAb after TSH stimulation (∆TgAbSTIM) was calculated as a percentage of the baseline level. Patient disease status was classified into no residual disease (ND) and residual or recurred disease (RD) by follow-up imaging studies and pathologic data. The characteristics and diagnostic value of serum TgAb levels and ∆ TgAbSTIM were investigated with respect to disease status. 38 patients were in the ND group and 15 were in the RD group. TgAbBAS, TgAbSTIM and TgAbF/U were significantly higher in the RD compared to the ND group (p = 0.0008, 0.0002, and