CEACAM5 and medullary thyroid gland carcinoma: Additional systematic laboratory tests indicated normal thyroid function (thyroid-stimulating hormone [TSH] 4.0 IU/mL, F-T4 0.77 ng/dL), calcium levels (9.8 mg/dL), carcinoembryonic antigen (CEA) levels (0.5 ng/mL), and calcitonin levels (25 pg/mL); none of the findings indicated medullary carcinoma.