Development and clinical impact of thyroglobulin antibodies in patients with differentiated thyroid carcinoma during the first 3 years after thyroidectomy

Abstract

Objective and design: Cross-sectional studies have reported an increased prevalence of circulating thyroglobulin autoantibodies (TgAbs) in patients with differentiated thyroid carcinoma (DTC). With the advent of more sensitive assays, a longitudinal study monitoring the development of TgAb levels after ablative therapy was warranted. Methods: One hundred and twelve consecutive patients with follicular cell-derived thyroid cancer were followed for 3 years. All patients had been thyroidectomized and received, on average, two radioiodine therapies. Residual tissue was quantified scintigraphically by 131 I 24-h uptake. TgAb and thyroglobulin (Tg) serum levels were determined with a sensitive direct radioligand assay and an IRMA respectively. Results: The prevalence of TgAbs at the initial examination was 29% (median 130 U/ml). During follow-up, TgAb levels rose transiently in one-tenth of the patients, but the prevalence of demonstrable TgAbs decreased to , 10% after 3 years. The median serum half-life of TgAbs in treated DTC patients was 10 weeks. At initial examination (when all patients still had residual thyroid tissue and 17 had metastases), rising TgAb levels were correlated with the inability to detect Tg in 4, 30 and 73% of the patients, when initial TgAbs were , 6, 6 -50 or .50 U/ml respectively. While the Tg recovery test was valid for all patients, an in vitro dilution assay with TgAb serum reduced Tg values by up to 32%. Conclusions: The development and course of TgAbs in DTC patients cannot be predicted by initial or residual tumour volume, TgAb or Tg levels. The presence of TgAbs, even in low concentrations, may cause Tg underestimation despite valid recovery tests in DTC patients.European Journal of Endocrinology 153 49-55

Undetectable pre-ablation thyroglobulin levels in patients with differentiated thyroid cancer: it is not always what it seems

“…Although undetectable pre-ablation Tg levels usually indicate complete previous surgery, our data reinforce earlier observations that, in a low percentage of patients, this situation may be related to non-detectable Tg or to the presence of TgAb (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)31). We believe that, when concurrent chronic thyroiditis is found by the pathologist, or when initial TNM stages are diswith DTC, compared with the 10% generally seen in the general population (20).…”

“…When TgAb are initially detectable, their serum level may decrease over subsequent months and years after adequate therapy, as thyroid tissue mass and Tg antigen levels decline (25,26). Patients may not achieve negative TgAb status during the first postoperative year, and may even exhibit a rise (or de novo appearance of TgAb during the 6 months after a radioiodine treatment, when there is release of Tg antigen secondary to lytic cell damage of thyroid tissue) (27,28).…”

“…Up to 20% of patients may present Tg-Antibodies (TgAb), which might obscure the evidence of detectable Tg (3,4). TgAb are also considered as surrogate markers for the persistence of disease (1,2,(6)(7)(8).…”

Modified dynamic risk stratification for predicting recurrence using the response to initial therapy in patients with differentiated thyroid carcinoma

“…The timing of TgAb measurement is likely to affect the prevalence of positive serum TgAb level because TgAb decreases and eventually disappears as it removes the antigenic stimulus from Tg after initial therapy (22). A previous study reported that TgAb continuously decreased in most patients after surgery and the prevalence of positive serum TgAb decreased to !10% after 3 years (23). In this study, the prevalence of positive serum TgAb was 15% at the time of the remnant ablation and decreased to 5% at the time of restratification, 6-24 months after initial treatment.…”

Protective autoimmunity in cancer (Review)

“…During follow-up, TgAb levels rose transiently in one-tenth of the patients, but the prevalence of demonstrable TgAbs decreased to <10% after 3 years. The presence of TgAbs in breast cancer cannot in the meantime predict the initial or residual tumor volume and its prognostic role is still unknown (28).…”