Evaluation of calcitonin measurement in fine needle aspirates in the diagnosis of primary and metastatic medullary thyroid carcinoma

Abstract

Serum CT represents the tumoral marker of medullary thyroid carcinoma (MTC), and is a main diagnostic tool and follow-up after treatment. Nevertheless, calcitonin levels can be elevated in a number of other situations and does not always distinguish MTC from other clinical circumstances, particularly when elevation remains moderate. Fine needle aspiration biopsy is a widely used examination for the investigation of thyroid nodules and lymph nodes, but its sensitivity for the diagnosis of MTC remains low ranging from 45% to 63%. Calcitonin measurement in fine needle aspiration wash out fluid has been reported as reliable, and is recommended by the experts of American Thyroid Association (ATA) in their 2015 consensus for the management of MTC even if its diagnostic is not standardized yet. Material and methods: Twenty patients with 45 lesions (thyroid nodule and lymph node) were included in this study; calcitonin was performed in each of them, the puncture needles were washed with 1ml of saline solution to obtain to measure Calcitonin in fine needle aspiration washout fluid. Results: After surgery 32 MTC were diagnosed on histology. Receiver operating curve (ROC curve) indicated CT in fine needle aspiration >22.99pg/ml as more accurate cut off value with a sensitivity and specificity of 96.87% and 100%. Calcitonin ratio was evaluated too, the cut off value being>0.64 with a sensitivity of 62.5% and specificity of 100%. Conclusion: Calcitonin in fine needle aspiration wash out fluid constitutes an excellent diagnostic tool of MTC with the use of 22.99pg/ml threshold.