Evaluation of Discordance in Differentiated Thyroid Cancer Patients with Negative Radioiodine Scans and Positive Thyroglobulin Values at the Ablation Outcome Control

Abstract

Objective: We aimed to evaluate the discordance of 5 mCi (185 MBq) I-131 whole body scan (WBS) and thyroglobulin (Tg) values at the ablation outcome control in differentiated thyroid cancer (DTC) patients who had thyroidectomy and then received radioiodine (RAI) ablation. Materials and Methods: We retrospectively evaluated 36 DTC patients who had RAI treatment in our department between 1992-2009 and whose 5 mCi (185 MBq) I-131 WBS were negative, but Tg values were ≥2 ng/ml during the ablation outcome control (Patient group). Thirty-six patients whose Tg values were 2 cm (p2 cm (p40 (p<0.01) were significantly different between lymph node and micrometastatic groups.Conclusion: I-131 WBS/Tg level discordance at the ablation outcome control is mainly caused by metastatic lymph nodes.

Keywords

• Differentiated thyroid carcinoma
• radioiodine ablation
• I-131 whole body scan
• lymph node metastases