TPO and medullary thyroid gland carcinoma: Additionally, anti-thyroid peroxidase (TPO) or other antibodies could be marked, calcitonin should be determined in case of suspected medullary carcinoma, RET (gene of tyrosine kinase receptor) mutation could be confirmed to exclude medullary carcinoma before planned surgery, or elastography could be performed before the planned FNAB to select the correct puncture site [29].