CALCA and medullary thyroid gland carcinoma: The main argument for this is that an increased Tg release is found not only in thyroid follicular cell-derived carcinomas (DTC) but also in various benign thyroid processes (e.g., thyroid enlargement, benign thyroid nodules, hyperthyroidism, thyroiditis), and it is therefore very unspecific [64], in contrast to calcitonin, which has a relatively high specificity with regard to “screening” for medullary thyroid carcinoma (MTC) [65].