Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2014) 35 P1140 | DOI: 10.1530/endoabs.35.P1140

ECE2014 Poster Presentations Thyroid Cancer (70 abstracts)

Thyroglobulin before radio remnant ablation during levothyroxine withdrawal can be considered an accurate parameter of remission of differentiated thyroid cancer

Rosa Maria Paragliola , Annapina De Rosa , Vincenzo Di Donna , Pietro Locantore , Paola Senes , Alessandro Prete , Alfredo Pontecorvi & Salvatore Maria Corsello

Endocrinology, Università Cattolica, Roma, Italy.

Introduction: Differentiated thyroid cancer (DTC) is the most frequent endocrine cancer. After surgery followed, if any, by 131I radio remnant ablation (RRA), follow-up monitoring consists of neck ultrasonography (US) and measurements of thyroglobulin (Tg) levels and anti-Tg antibodies (Ac-Tg) both on levothyroxine (L-T4) therapy and after recombinant TSH (rTSH). The aim of our study is to define a cut-off of Tg before RRA (RRA-Tg) during L-T4 withdrawal predictive of remission of disease.

Materials and methods: We prospective evaluated 113 patients who underwent total thyroidectomy with or without lymphadenectomy for DTC. All patients received RRA after surgery, without evidence of iodine uptake outside neck. Ac-Tg were negative. Tg after rTSH stimulation (rTSH-Tg) was performed 9–12 months after RRA. During follow-up patient was considered ‘free of disease’ on the basis of undetectable Tg values on suppressive L-T4 therapy (L-T4-Tg), rTSH-Tg < 2 ng/ml, negative Ac-Tg and negative neck US.

Results: RRA-Tg was between 0.5 and 117 ng/ml (mean±S.D.: 7.52±14.06); L-T4-Tg was between 0.01 and 1.00 ng/ml (mean±S.D. 0.15±0.20); rTSH-Tg was between 0.02 and 15.00 ng/ml (mean±S.D.: 0.58±2.06). 107 patients (94.7%) showed rTSH-Tg ≤2 ng/ml; six patients (5.3%) had rTSH-Tg ≥2 ng/ml. ROC curve demonstrated that RRA-Tg can be considered highly predictive of negative rTSH-Tg. In particular, for RRA-Tg values of 10 ng/ml sensitivity and specificity are of 100 and 83% respectively; for RRA-Tg values of 18.35 ng/ml sensitivity and specificity are of 100 and 95% respectively.

Conclusions: RRA-Tg can be considered an accurate parameter to predict the remission of DTC. For RRA-Tg values <18.35 ng/ml, during subsequent follow-up the possibility to avoid rTSH-Tg test should be considered in presence of undetectable L-T4-Tg levels, negative Ac-Tg and negative neck US.

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