title: Calcitonin measurement on fine needle washouts: preanalytical issues and normal reference values.
abstract: Calcitonin (CT) measurement on fine-needle aspiration cytology (FNAC) washouts (FNAC-CT) is a promising tool in the diagnosis of medullary thyroid carcinoma (MTC). Guidelines for the method with codified cut-off are needed to use this technique in clinical routine. This study was undertaken to assess the best pre-analytical procedure and to define a reliable reference value for FNAC-CT. Fifty-four patients underwent thyroid surgery, so MTC was excluded by surgical pathology examination and CT immunostains. Before surgery, FNAC-CT was measured on 78 thyroid nodules from such 54 patients. Needles were rinsed by normal saline and specific CT-free dilution buffer, and CT was measured by a fully automated immunochemiluminometric assay. FNAC-CT levels were not significantly different in normal saline or specific buffer. The calculated 97.5th upper FNAC-CT value was 8.5 pg/mL (saline) and 7.43 pg/mL (buffer), respectively. Seeing its relatively large sample size, rigorous selection criteria and inclusion of CT immunostaining of thyroid nodules, the present study provides a reliable guideline and a clinically relevant reference value for FNAC-CT measurement in thyroid nodules.
authors.affiliation: Department of Nuclear Medicine and Thyroid Centre, Oncology Institute of Southern Switzerland, CH-6500 Bellinzona, Switzerland. luca.giovanella@eoc.ch
authors.forename: Luca
authors.initials: L
authors.lastname: Giovanella
authors.forename: Luca
authors.initials: L
authors.lastname: Ceriani
authors.forename: Massimo
authors.initials: M
authors.lastname: Bongiovanni
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000097:blood / Q000737:chemistry / Q000473:pathology*; D044963:Biopsy, Fine-Needle; D002116:Calcitonin / Q000032:analysis*; D002277:Carcinoma / Q000097:blood / Q000737:chemistry / Q000473:pathology*; D018276:Carcinoma, Medullary / Q000097:blood / Q000737:chemistry / Q000473:pathology*; D002291:Carcinoma, Papillary; D005260:Female; D006044:Goiter, Nodular / Q000097:blood / Q000473:pathology*; D006801:Humans; D057230:Limit of Detection; D008297:Male; D012016:Reference Values; D012965:Sodium Chloride / Q000737:chemistry; D012995:Solubility; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000097:blood / Q000737:chemistry / Q000473:pathology*; D016606:Thyroid Nodule / Q000097:blood / Q000737:chemistry / Q000473:pathology*; D013965:Thyroidectomy
chemical_list: D012965:Sodium Chloride; D002116:Calcitonin