Method: At the time of L-T4 withdrawal or after thyroidectomy, patients with DTC awaiting WBS or radioiodine treatment were randomized in two groups (double-blind): L-T3 (50 mg qd) or an identical placebo for 3 weeks, after which treatment was stopped for 2 weeks. A validated questionnaire of signs and symptoms of hypothyroidism (Billewicz's scale) was administered every 2 weeks until the WBS. TSH, fT4 and fT3 were measured weekly.