For the 21 cases (36%) in which calcitonin was evaluated both preoperatively and postoperatively, serum calcitonin levels showed elevated preoperative values between 38–2000 pg/mL and normalized postoperative values (between 2–11.5 pg/mL) or persisted at increased levels (between 21–2000 pg/mL); in cases with familial MTC, two patients presented postoperative normalized calcitonin whereas the other two maintained high calcitonin levels. The gene discussed is CALCA; the disease is medullary thyroid gland carcinoma.