CEACAM5 and medullary thyroid gland carcinoma: Alternative serum markers of MTC were also considered in some patients: carcinoembryonic antigen (CEA) was above the upper reference limit in 1 of 12 cases; chromogranin A (CgA) was normal in 3 of 3 cases; and procalcitonin (PCtn) was moderately increased in the one case in which this marker was analyzed.