Endocrine Abstracts

Objectives: We studied whether the postoperative serum thyroglobulin (TG) basal levels before treatment with I131 (baseline TG) could be related with the response to treatment. We consider the excellent response as the absence of clinical, biochemical disease (undetectable TG and anti-thyroglobulin antibodies AcTG negative) and/or structural disease.

Material and Methods: This is an observational study that includes 100 patients with differentiated thyroid carcinoma (CDT) who underwen total thyroidectomy and radioiodine therapy as initial treatment, during 2017 and 2018 in our center, with a minimum follow-up of 12 months. Clinical, radiological and biochemical data have been analyzed during the administration of I131 (after rhTSH stimulation) and in the follow-up (at 3, 6 and 12 months).

Results: It is a cohort of 100 patients (74% women) with an average age of 50.9 (range 23–82) years. Total thyroidectomy was performed in 56% and 44% required lymphadenectomy. 38% of patients diagnosed with Ac antiTg at diagnosis. The most frequent histology in our sample was papillary carcinoma (87%). The TNM classification is: stage 1: 75%, stage 2: 17%, stage 3: 5% and stage 4: 3%. According to the ATA classification, 41% of patients present a low risk of recurrence, 27% an intermediate risk and 22% a high risk. The average mean Tg level in patients with negative AcTg was 10 ng/ml. The 83% of these patients showed an excellent response to treatment, 12 months after treatment. They all presented a baseline TG equal to or less than 3.3 ng/l.

Conclusion: In our study, presenting a baseline TG value greater than 3.3 ng/ml implies an absence of excellent response one year after treatment with I131.