Rising serum antithyroglobulin antibody levels predict recurrence of differentiated thyroid carcinoma in thyroglobulin-negative patients



SUMMARY BACKGROUND Serum antithyroglobulin antibodies (TgAbs) are found in 10 to 25% of patients with differentiated thyroid carcinoma (DTC), as compared with an incidence of approximately 10% in the general population. This poses a serious problem in the follow-up of patients with DTC, as circulating TgAb interferes with serum thyroglobulin (Tg) measurements performed by immunometric assays. Thyroid cancer management guidelines suggest that TgAb levels serve as a surrogate for serum Tg measurement during follow-up, providing TgAb is measured in the same laboratory. Kim et al. hypothesize that changes in serum TgAb might predict tumor outcome, which has been a point of contention in previous studies. The aim of this study was to determine whether a changing pattern of TgAb levels found soon after thyroidectomy could serve as a prognostic indicator. METHODS This retrospective study was performed on 1499 consecutive patients treated for DTC in the authors' hospital from 1995 through 2003. All had total thyroidectomy followed by remnant ablation with 100 to 150 mCi (3.7 to 5.55 GBq) of 131 I about 6 weeks after surgery. Patients selected for study had no preoperative evidence of extracervical tumor, or 131 I uptake outside the thyroid bed on the posttreatment whole-body scan (RxWBS) or in the thyroid bed on the first diagnostic whole-body scan (DxWBS) during follow-up. Patients with extracervical metastases or poorly differentiated or anaplastic thyroid cancer were excluded from the study. Follow-up DxWBS was performed with 4 mCi (148 MBq) of 131 I after thyroid hormone withdrawal every 3 to 6 months along with serum Tg and TgAb measurements. When serum Tg was above

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    Thyroid 03/2006; 16(2):109-42. DOI:10.1089/thy.2006.16.ft-1 · 4.49 Impact Factor
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    ABSTRACT: In the present investigation we studied serum anti-thyroglobulin and anti-thyroid microsomal autoantibodies, measured by hemagglutination technique, in 600 patients with thyroid cancer seen by us from 1975 to 1985 (mean follow-up 46 months). Positive thyroglobulin antibodies and/or microsomal antibodies were found in 138 (23%) patients (23.9% with papillary, 25% with follicular, 16.1% with anaplastic, and 4.1% with medullary thyroid carcinomas). The incidence of positive tests was similar in each decade of life (ranging between 21.9% and 27.9%), whereas in a normal sex-matched population with no evidence of thyroid disease, the frequency of positive tests was very low in young people and increased to 23% in people older than 60. In 64 patients with no evidence of residual or metastasic thyroid tissue after surgery and radioiodine, initially positive antibody titres became negative in 54.6%, decreased in 32.8%, did not change in 3.1%, and increased in 9.3%. On the contrary, antibody titres of patients with persistent disease became undetectable in 8.3%, decreased in 16.6%, remained unchanged in 25%, and increased in 50%. The clinical course of differentiated thyroid cancer was unaffected by the presence of thyroid antibodies and no difference was found in the death rate between antibody-positive and antibody-negative patients (11.5% and 13.6%, respectively). In conclusion, our data indicate that: 1) autoimmune phenomena are not an infrequent finding in thyroid cancer; 2) as in non-malignant thyroid diseases, positive-antibody tests are more frequently observed in females than in males; 3) at variance with normal controls, no age-dependent increase in serum anti-thyroid antibodies was found in thyroid cancer; 4) the presence of metastatic thyroid tissue seems to be necessary to perpetuate the autoantibody synthesis, and 5) anti-thyroid autoantibodies are not a protective or worsening factor in the tumour outcome.
    Acta endocrinologica 12/1988; 119(3):373-80. DOI:10.1530/acta.0.1190373
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    ABSTRACT: 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. 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 131I 24-h uptake. TgAb and thyroglobulin (Tg) serum levels were determined with a sensitive direct radioligand assay and an IRMA respectively. 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%. 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 07/2005; 153(1):49-55. DOI:10.1530/eje.1.01940 · 4.07 Impact Factor
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