Whether this is the optimal cutoff, including other diagnostic characteristics, has only been partially evaluated in research.<h4>Objective</h4>The aims of this study were to evaluate the current calcitonin-driven recommendation and to investigate whether other diagnostic characteristics can be added to improve prediction of M1 disease at diagnosis.<h4>Methods</h4>Adult MTC patients treated in a tertiary care hospital between 1984 and 2023 with a preoperative calcitonin measurement were retrospectively collected. The gene discussed is CALCA; the disease is medullary thyroid gland carcinoma.