Calcitonin testing in patients with thyroid nodules for screening medullary thyroid carcinoma: a 'gray zone'

Introduction. The results of the calcitonin (Ctn) study in patients with thyroid nodules are included in the clinical guidelines for the treatment of differentiated thyroid cancer. However, the management of patients with moderately elevated Ctn up to 100 pg/mL is not clearly defined.Materials and methods. The study included 103 patients with thyroid nodules and a Ctn level above the reference, but not more than 100 pg/ml. The Ctn concentration was determined using the Cobas e platform (Roche, Germany) or by the immunoradiometric method (Izotop, Hungary). 45 patients were operated on. The analysis of the incidence of medullary thyroid carcinoma (MTC), other thyroid and nonthyroid pathology in patients with elevated Ctn scan was carried out. The results of additional examination are presented: the serum cancer embryonic antigen, Ctn in wash-out, stimulated Ctn, gene RET mutation testing.The study objective is to evaluate the probability MTC with Ctn level 2000 pg/mL in mTC and up to 938 pg/mL in patients with histologically confirmed absence of MTC.Conclusion. If the Ctn level is