OBJECTIVES: The prognostic value of thyroglobulin antibody (TgAb) and its trends during follow-up periods may guide the treatment plans in patients with differentiated thyroid cancer (DTC) following surgery, however, there is still a lack of sufficient data. This study aims to evaluate the impact of change trends in TgAb levels on the prognosis of patients with DTC and to explore its potential application in clinical practice. MATERIALS AND METHODS: A retrospective analysis was conducted on the medical records of 2,981 DTC patients who underwent surgery followed by RESULTS: Pre-treatment TgAb levels in the Negative Conversion Group were significantly lower than those in the other three groups ( CONCLUSIONS: Negative conversion or a decrease in TgAb levels was associated with a favorable prognosis, whereas stable or increased TgAb levels indicated a higher risk of persistent/recurrent DTC. For patients with positive TgAb serum levels, monitoring the TgAb trend changes during follow-up should be a clinical priority, with timely adjustments to individualized treatment plans.