[Value of Baseline Calcitonin for Differential Diagnosis of Medullary Thyroid Cancer]

Objective: To analyze the efficacy of using baseline calcitonin (bCtn) for auxiliary diagnosis of medullary thyroid cancer (MTC) in the hypercalcitoninemic population with thyroid nodules and to explore the relationship between preoperative levels of bCtn and carcinoembryonic antigen (CEA) and MTC staging.

Methods: The clinical, pathological, imaging, and lab test data of 58 MTC patients and 84 non-MTC patients were retrospectively reviewed in the study. The patients were hospitalized at West China Hosptal, Sichuan University between 2011 and 2020. Receiver operating characteristic (ROC) curves were constructed to calculate the MTC diagnostic efficacy of bCtn and CEA. The differences in the preoperative bCtn and CEA levels of MTC patients with different primary tumor sites and regional lymph node involvement were compared.

Results: The bCtn cutoff values were 31.54 pg/mL for men and 22.60 pg/mL for women for diagnosing MTC in the hypercalcitoninemic population with thyroid nodules. There were statistical differences in preoperative bCtn levels ( H=16.166, P=0.001) and in preoperative CEA levels ( H=9.447, P=0.024) in MTC patients of different T stages. There were statistical differences in preoperative bCtn levels ( H=7.919, P=0.019) and in preoperative CEA levels ( H=7.934, P=0.019) in MTC patients of different N stages.

Conclusion: The best bCtn cutoff values for the diagnosis of MTC in the hypercalcitoninemic population with thyroid nodules and are 31.54 pg/mL for men and 22.60 pg/mL for women.