Endocrine Abstracts

Aim: To know if Tg levels after treatment (total thyroidectomy and radioiodine ablation) in the DTC can predict their prognosis in the long term.

Material and methods: Basal Tg and Tg after rh-TSH were measured in 229 patients with DTC without any evidence of residual tumour (negative neck ultrasonography) after treatment. The group was followed until tumour recurrence or, if recurrence was not found, a minimum of 12 month (mean ± SD =63±37 months).

Test response was classified in three categories: Excellent response: Tg stimulated <1 ng/ml; indeterminate response: 1–10 ng/ml and incomplete response: >10 ng/ml. All selected cases had negative Tg-antibodies.

Results: The relationship between Tg level and recurrence is described in the following table.

When initial Tg levels were positive, but tumour recurrence was not detected at the end of the follow up (n=32), the evolution of Tg stimulated levels was studied. Eight out of 32 patients showed an increase of Tg levels, in 3 cases Tg levels were stable, in 8 patients Tg decreased and in other 6 cases Tg became indetectable (without any additional treatment). In 7 patients Tg stimulated was no measured.

Conclusions: 1. When Tg stimulated levels post-treatment are undetectable the possibility of recurrence is minimal.

2. The probability of recurrence increases according to Tg levels.

3. However, it has to be considered that a positive Tg level can decrease and even become negative during the follow-up.