The Diagnostic Value of Calcitonin Measurement in Wash-Out Fluid from Fine-Needle Aspiration of Thyroid Nodules in the Diagnosis of Medullary Thyroid Cancer

Objectives: The diagnostic value of calcitonin measurement in fine-needle aspiration biopsy (FNAB) wash-out fluid (Ct-FNAB) for medullary thyroid cancer (MTC) remains to be determined. This prospective study aimed to assess the diagnostic value of Ct-FNAB in thyroid nodules in comparison with basal serum calcitonin (Ct), pentagastrin-stimulated Ct (Pg-sCt), and cytology.Methods: Among patients with goiter addressed with US-FNAB who had an initial clinical suggestion for thyroidectomy, 27 patients with thyroid nodule/s (n = 60) and normal, borderline, or increased Ct fulfilled the criteria for thyroidectomy. All 27 patients (enrolled according to exclusion/inclusion criteria) underwent ultrasonography (US), Ct, Pg-sCt, US-assisted FNAB of each patient's nodule for both cytology, and Ct-FNAB before thyroidectomy.Results: Ct-FNAB always resulted in >1,000 pg/mL in MTC nodules at histology. For values between 36 and 1,000 pg/mL, MTCs and nodular or micronodular C-cell hyperplasia (CCH) results overlapped. Mos...