However, comprehensible reasons to abstain from FNAC are elevated basal calcitonin values, which indicate the presence of medullary thyroid carcinoma, the clear indication of malignant diagnoses by radiological imaging (e.g., with cervical lymph node metastases), small nodule size of less than 1 cm in diameter or the fact that the patient refuses this preoperative diagnostic option. This evidence concerns the gene CALCA and medullary thyroid gland carcinoma.