CALCA and medullary thyroid gland carcinoma: In our cohort, a moderate and statistically significant positive correlation was observed between serum calcitonin levels and nodule size (r = 0.52, p = 0.018), as well as between ES and nodule size (r = 0.48, p = 0.034), suggesting that larger MTC nodules tend to be both more secretory and stiffer.