CALCA and metastatic malignant neoplasm in the lymph nodes: Patients with intrathyroidal MTC larger than 1–1.5 cm and calcitonin levels of more than 40 ng/L are at higher risk of lymph node metastases and should be considered for central lymphadenectomy (Machens et al. 2009, Rohmer et al. 2011, Machens & Dralle 2012, Wells et al. 2015, Machens et al. 2021c).