The median Tg level following TSH stimulation at the time of the discovery of BM for a patient with C-BM-R was relatively low at 12.5 ng/ml (IQR: 3.9–31.1) in accordance with the low tumor burden and was 0.7 ng/ml (IQR: 0.07–8) after RAI treatment. Here, TG is linked to neoplasm.