RESUMEN
PURPOSE: Anti-thyroglobulin antibodies (TgAb) can be used as a surrogate tumor marker in the follow-up of papillary thyroid carcinoma (PTC). We try to determine if the change in TgAb levels in the first post-operative year is a good predictor of persistence/recurrence risk in TgAb-positive PTC patients. METHODS/PATIENTS: 105 patients with PTC who underwent thyroidectomy between 1988 and 2014 were enrolled. We calculated the percentage of change in TgAb levels with the first measurement at 1-2 months after surgery and the second one at 12-14 months. RESULTS: TgAb negativization was observed in 29 patients (27.6%), a decrease of more than 50% was observed in 57 patients (54.3%), less than 50% in 12 patients (11.4%) and in 7 patients (6.7%) the TgAb level had increased. The percentage of persistence/recurrence was 0, 8.8, 16.7 and 71.4% in each group, respectively (p < 0.001). In the multivariate analysis, only the percentage of change in TgAb showed a significant association with the risk of persistence/recurrence, regardless of other factors such as age, size and TNM stages. CONCLUSIONS: Changes in TgAb levels in the first year after surgery can predict the risk of persistence/recurrence of TgAb-positive PTC patients. Patients who achieved negativization of TgAb presented an excellent prognosis.