Following thyroidectomy, the Tg level decreases dramatically to 0.7 ng/mL (0.7 μg/L).<h4>Discussion</h4>Significantly elevated Tg levels after TL warrant careful consideration, but it is crucial to exclude potential laboratory errors and assay interference; additionally, it is essential to rule out underlying metastatic disease.<h4>Conclusion</h4>Measuring Tg and Tg antibody levels post-TL can provide a baseline for future reference. Here, TG is linked to metastatic neoplasm.