Routine calcitonin measurement in patients with nodular thyroid disease is rather controversial. The aim of this study was to evaluate the contribution of serum calcitonin measurement in the diagnostic evaluation of thyroid nodules with insufficient, indeterminate, or suspicious cytology. Out of 1668 patients who underwent thyroidectomy with the diagnosis of nodular thyroid disease and were screened, 873 patients with insufficient, indeterminate, or suspicious fine needle aspiration biopsy results were included in the study. From the total number of patients in this study, 10 (1.1%) were diagnosed as medullary thyroid cancer (MTC) using histopathology. The calcitonin level was detected to be above the assay-specific cut-off in 23 (2.6%) patients ranging between 6.5 - 4450 pg/mL. While hypercalcitoninemia was detected in all 10 MTC patients, a false positive elevation of serum calcitonin was detected in 13 patients (1.5%). Of the MTC group, 7 patients had cytology results that were suspicious for malignancy (Bethesda V), one patient's cytology showed atypia of undetermined significance (Bethesda III) and two patient's cytology results were suspicious for follicular neoplasm (Bethesda IV). Among the cases with non-diagnostic cytology (Bethesda I), none of the patients were diagnosed with MTC. In conclusion, routine serum calcitonin measurement can be performed in selected cases rather than in all nodular thyroid patients. While it is reasonable to perform routine calcitonin measurement in patients with Bethesda IV and Bethesda V, this measurement was not useful in Bethesda I patients. In Bethesda III patients, patient-based decisions can be made according to their calcitonin measurement.

中文翻译：

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血清降钙素常规测定对甲状腺结节细胞学检查不足、不确定和可疑的价值。

结节性甲状腺疾病患者的常规降钙素测量颇具争议。本研究的目的是评估血清降钙素测量在诊断评估细胞学不充分、不确定或可疑的甲状腺结节中的作用。在 1668 名被诊断为结节性甲状腺疾病并接受筛查的甲状腺切除术患者中，873 名细针穿刺活检结果不充分、不确定或可疑的患者被纳入研究。在本研究的患者总数中，10 名（1.1%）通过组织病理学诊断为甲状腺髓样癌（MTC）。23 名 (2.6%) 患者的降钙素水平在 6.5 - 4450 pg/mL 之间被检测到高于测定特异性临界值。虽然在所有 10 名 MTC 患者中检测到高降钙素血症，13 名患者（1.5%）检测到血清降钙素假阳性升高。在 MTC 组中，7 例患者的细胞学结果怀疑为恶性肿瘤（Bethesda V），1 例患者的细胞学结果显示意义不明的非典型性（Bethesda III），2 例患者的细胞学结果怀疑为滤泡性肿瘤（Bethesda IV）。在细胞学未确诊的病例（Bethesda I）中，没有患者被诊断为 MTC。总之，常规血清降钙素测量可以在选定的病例中进行，而不是在所有结节性甲状腺患者中进行。虽然对 Bethesda IV 和 Bethesda V 患者进行常规降钙素测量是合理的，但该测量对 Bethesda I 患者无用。在 Bethesda III 患者中，