A 34-year-old lady had total thyroidectomy and neck dissection. Papillary carcinoma of thyroid 4.5 cm, extra capsular invasion present with 9 out of 13 nodes positive. Underwent radioiodine scan in July 2015. Only focal uptake in thyroid bed.

In December 2015, her Thyroglobulin is 186. The Thyroglobulin antibody is normal (2.2) Radioiodine scan and treatment (100 mCi) done. No uptake seen anywhere. What should be the next treatment?