Empiric I-131 Treatment of High Thyroglobulin Levels in Differentiated Thyroid Carcinoma After Remnant Ablation

Aim: The objective of this study is to establish the efficacy of empiric 1-131 treatment (EIT) given for patients whose thyroglobulin(Tg) levels remained high after ablative 1-131 treatment (AIT). Methods: Fifty-six patients (46 women, 10 men; mean age 47.4 +/- 16.8), without distant metastasis, who were treated empirically for high Tg levels after AIT in our clinic, were retrospectively studied. In all patients stimulated Tg levels before AIT (Tg I) and 6 months after AIT (Tg II) were measured. After EIT, post-therapeutic whole-body scintigraphy (PWBS) was performed to all patients. 18F-FDG PET CT was performed to patients who had negative PWBS but continued to have high Tg II levels. Results: PWBS was positive in 28 patients (50%) and negative in 28 patients (50%). Twenty-eight patients did not respond to EIT (50%), and 28 patients (50%) responded to EIT at different rates. Sixteen patients (28.6%) responded to EIT completely, and 12 patients (21.4%) responded to EIT partially. Tg I was 60.7 +/- 40 ng/ml and Tg H was 31 +/- 20.4ng/ml in responding patients, whereas Tg I was 87 ng/ml and Tg II was 114.3 +/- 106 ng/ml in unresponding ones. 18F-FDG PET CT was positive in 22 patients and negative in 6. Conclusion: Our findings, suggested that the EIT is not beneficial in patients who have higher Tg II than Tg land the cure rate is low in increasing Tg levels. The patients who have high Tg II but lower than Tg I can be treated empirically with 1-131