CEACAM5 and medullary thyroid gland carcinoma: Among them, the ones with LM (half of our patients with MEN2) all had highly elevated serum levels of Ctn and CEA, which are known as indicators of distant metastases in MTC [2, 24], as it is reported in the literature that in the presence of increasing tumor infiltration or distant metastases the Ctn-level and CEA-levels will rise to more than 400pg/ml and 100 ng/ml, respectively [19, 26].