Introduction: Association between hypercalcitoninemia and pathological conditions such as autoimmune thyroiditis (AIT) or differentiated thyroid carcinoma (DTC) has been addressed, with conflicting results. We evaluated the prevalence and the clinical relevance of elevated basal serum calcitonin (CT) levels in non-neoplastic (nodular goiter [NG] and AIT) and neoplastic thyroid diseases (DTC). Methods: We retrospectively evaluated 3,250 consecutive patients with thyroid nodular disease who underwent fine-needle aspiration cytology with adequate sample. After exclusion of medullary thyroid cancer (MTC) patients were divided according to the presence/absence of thyroid autoimmunity into NG or nodular autoimmune thyroiditis (N-AIT) and, according to cytological results, in benign or suspicious/malignant nodules. Results: One hundred ninety-seven/3,250 patients (6.0%) showed CT level >10 pg/mL. In 11/3,250 (0.3%) cases, a final histological diagnosis of MTC was made, while the remaining 186/3,250 patients (5.7%) had non-MTC-related hypercalcitoninemia (CT > 10 pg/mL). According to cytological diagnosis, the rate of hypercalcitoninemia was similar in class II and class V–VI groups (5.4 vs. 6.9%, p = 0.4). The occurrence of hypercalcitoninemia was significantly higher in patients with NG (166/2,634 [6.3%]) than in patients with N-AIT (20/605 [3.3%]) (p = 0.004). However, after matching by sex, no difference was found between the 2 groups (NG and N-AIT). These results were confirmed in 598 patients submitted to surgery. Conclusions: AIT and DTC seem not to affect serum CT levels in patients with thyroid nodules. Therefore, hypercalcitoninemia, in these patients, should be submitted to the same diagnostic workup than patients without AIT or DTC.

Background: A possible impact of obesity on the risk of thyroid cancer has been postulated in some studies, but it remains controversial. Objective: To investigate the association between obesity and differentiated thyroid carcinoma in a population of unselected patients subjected to fine-needle aspiration cytology (FNAC) for thyroid nodules. Methods: We retrospectively evaluated the results of FNAC of thyroid nodules in 4,849 patients (3,809 females and 1,040 males; mean age 55.9 ± 14.1 years). Patients were stratified according to their body mass index (BMI). There were 1,876 (38.7%) normal-weight patients (BMI 18-24.9), 1,758 (36.2%) overweight (BMI 25-29.9), 662 (13.7%) grade 1 obese (BMI 30-34.9), 310 (6.4%) grade 2 obese (BMI 35-39.9) and 243 (5.0%) grade 3 obese (BMI >40). Results: The prevalence of suspicious or malignant nodules (Thy4/Thy5) did not differ across the 5 BMI groups, i.e. it was 6.8% in normal-weight patients, 6.3% in overweight patients, 6.3% in grade 1 obese patients, 4.0% in grade 2 obese patients and 4.2% in grade 3 obese patients (p = 0.29). The prevalence of Thy4/Thy5 nodules did not differ when males and females were evaluated separately (p = 0.22 and p = 0.12, respectively). A significant, lower rate of Thy4/5 cytology was observed in female patients with grade 2-3 obesity (odds ratio 0.51; 95% confidence interval 0.284-0.920; p = 0.009). Conclusions: The results of this study, in a retrospective series of patients with thyroid nodules, do not confirm previous findings reporting an association between obesity and differentiated thyroid carcinoma. Thus, obese patients with nodular thyroid disease should be managed the same as normal-weight patients.