Changes in thyroglobulin antibodies after treatment of differentiated thyroid cancer and its influencing factors

To investigate the changes in thyroglobulin antibodies (TgAb) and its influencing factors in differentiated thyroid cancer (DTC) patients with positive TgAb (>115 U/ml) after total thyroidectomy and radioiodine (¹³¹I) therapy.

We collected the clinical data of 118 DTC patients with positive TgAb and analyzed their TgAb levels before surgery, before ¹³¹I therapy, and after ¹³¹I therapy with a median follow-up of 2.3 months and 5.2 months. Multiple linear regression (MLR) was applied to analyze the time of TgAb concentration decreased by more than 50% (T₅₀) and its influencing factors.

Compared with the previous TgAb levels, TgAb decreased significantly 2.3 months and 5.2 months after surgery or after ¹³¹I therapy, respectively (both P=0.000). The proportions of patients with TgAb decreased by more than 50% in each stage were 28.6%,33.3%, and 37.2%,respectively. The negative conversion ratios were 23.4%,48.9%, and 62.8%,respectively. MLR showed that only the interval between surgery and ¹³¹I therapy was correlated with T₅₀ (B=1.125, P=0.000).

The TgAb levels in DTC patients remarkably decrease after surgery and after ¹³¹I therapy. The interval between surgery and ¹³¹I therapy remarkably influences the lowering speed of TgAb levels. Prompt application of ¹³¹I therapy after surgery helps to lower TgAb levels.