Preablation Stimulated Thyroglobulin/TSH Ratio as a Predictor of Successful I¹³¹Remnant Ablation in Patients with Differentiated Thyroid Cancer following Total Thyroidectomy

Abstract

Background. About 90% of thyroid cancers are differentiated thyroid cancers. Standard treatment is total thyroidectomy followed by radioactive I131remnant ablation and TSH suppression with thyroxine. Unsuccessful ablation drastically affects the prognosis of patients with DTC particularly high risk individuals; therefore, identifying the factors that affect the success of ablation is important in the management of patients with DTC. sTg is a good predictor of successful ablation in DTC. Its levels can be influenced by tumor staging and TSH values, as well as other factors. Therefore, we did this study using TSH to correct the predictive value of sTg in success of RRA. Methods. We retrospectively reviewed the records of 75 patients with DTC, who underwent total thyroidectomy followed by RRA and TSH suppression. Results. Preablation sTg and sTg/TSH ratio are significantly associated with ablation outcome. Cutoff value for sTg to predict successful and unsuccessful ablation was 18 ng/mL with 76.7% sensitivity and 79.1% specificity, while for sTg/TSH cutoff was 0.35 with 81.4% sensitivity and 81.5% specificity (P < 0.001). Association was stronger for sTg/TSH ratio with adjusted odds ratio (AOR) 11.64 (2.43–55.61) than for sTg with AOR 5.42 (1.18–24.88). Conclusions. Preablation sTg/TSH ratio can be considered as better predictor of ablation outcome than sTg, tumor size, and capsular invasion.

Prediction of radioactive iodine remnant ablation failure in patients with differentiated thyroid cancer: A cohort study of 740 patients

“…Our study was performed on a large number of patients with nonmetastatic DTC, and demonstrated that the Tg/TSH ratio is significantly more associated with ablation outcome than Tg alone. This finding is consistent with a previous study by Zubair Hussain et al Results of several noncontrolled retrospective studies suggest that a TSH value of >30 mU/L is associated with increased I‐131 uptake in tumors . In contrast, studies using single‐dose exogenous TSH stimulation suggest that maximal thyrocyte stimulation is reached when TSH levels are between 51 and 82 mU/L …”

Efficacy and Affecting Factors of 131I Thyroid Remnant Ablation After Surgical Treatment of Differentiated Thyroid Carcinoma

“…Many studies report that high sTg level before the first 131 I ablation is associated with lower success rate of 131 I ablation and sTg has an important predictive value for successful 131 I ablation (13, 34–36). Tamilia et al (37) and Zubair et al (38) report that the cutoff sTg values for prediction of successful or unsuccessful thyroid remnant ablation are 6 and 18 ng/ml, respectively. In these two studies, the sensitivities of sTg to predict unsuccessful thyroid remnant ablation are 67 and 76.7%, respectively, and the specificities are 79 and 79.1%, respectively (37, 38).…”

“…Tamilia et al (37) and Zubair et al (38) report that the cutoff sTg values for prediction of successful or unsuccessful thyroid remnant ablation are 6 and 18 ng/ml, respectively. In these two studies, the sensitivities of sTg to predict unsuccessful thyroid remnant ablation are 67 and 76.7%, respectively, and the specificities are 79 and 79.1%, respectively (37, 38). Our data also display that the success rate of the first 131 I ablation is clearly lower in the group with higher pre-ablation sTg level.…”

Is Very High Thyroid Stimulating Hormone Level Required in Differentiated Thyroid Cancer for Ablation Success?

“…In the literature, some studies have reported that the serum Tg/serum TSH ratio was an important predictor of ablation success that correlated well with patient outcomes. Moreover, they suggested that this rate and similar laboratory parameters might be considered while determining risk stratifications of DTC patients (13,14). Although a high TSH level (≥30 mIU /L) is recommended for ablation success in all textbooks, to the best of our knowledge there is only one study that assesses the correlation between ablation success and low TSH level (<30 mIU/L) in the literature.…”