Iodine 131 dose selection for nail clearing Currently, the first nail clearing treatment is usually done at a fixed dose of 3.7 GBq (100 mCi) of 131I. In some patients (especially low- and intermediate-risk patients), lower doses (e.g., 30-75 mCi) can be effective, but the success rate of a single treatment may be low. The first dose of nail clearing treatment should be reduced in patients with high residual thyroid tissue and combined with abnormal renal function. In children with DTC, the dose of nail cleansing treatment should be adjusted according to body weight or body surface area. In the following cases, 3.7-7.4 GBq (100-200 mCi) 131I can be applied directly: a large number of residual DTC lesions that cannot be removed surgically; lymph nodes or distant metastases in the neck that are inoperable or the patient refuses surgery; unexplained and markedly elevated serum Tg levels. In this case, nail clearing treatment is combined with the purpose of focal clearance. Recommendation 2-14: 131I dose of 1.11-3.7 GBq (30-100 mCi) for nail clearance in patients with non-high risk DTC. (Recommendation level B) Recommendation 2-15: For patients with intermediate or high risk DTC with focal clearance, the 131I dose for nail clearance is 3.7-7.4GBq (100-200mCi) 131I.(Recommendation level C)