title: Thyroglobulin assay in fluids from lymph node fine needle-aspiration washout: influence of pre-analytical conditions.
abstract: The aim of this study was to evaluate the pre-analytical factors contributing to uncertainty in thyroglobulin measurement in fluids from fine-needle aspiration (FNA) washout of cervical lymph nodes. We studied pre-analytical stability, in different conditions, of 41 samples prepared with concentrated solutions of thyroglobulin (FNA washout or certified standard) diluted in physiological saline solution or buffer containing 6% albumin. In this buffer, over time, no changes in thyroglobulin concentrations were observed in all storage conditions tested. In albumin free saline solution, thyroglobulin recovery rates depended on initial sample concentrations and on modalities of their conservation (in conventional storage tubes, recovery mean was 56% after 3 hours-storage at room temperature and 19% after 24 hours-storage for concentrations ranged from 2 to 183 μg/L; recovery was 95%, after 3 hours or 24 hours-storage at room temperature, for a concentration of 5,656 μg/L). We show here that these results are due to non-specific adsorption of thyroglobulin in storage tubes, which depends on sample protein concentrations. We also show that possible contamination of fluids from FNA washout by plasma proteins do not always adequately prevent this adsorption. In conclusion, non-specific adsorption in storage tubes strongly contributes to uncertainty in thyroglobulin measurement in physiological saline solution. It is therefore recommended, for FNA washout, to use a buffer containing proteins provided by the laboratory.
authors.affiliation: Département de biochimie et génétique, CHU, Angers, France, Groupe de biologie spécialisée de la Société française de médecine nucléaire, Paris, France.
authors.forename: Florence Boux de
authors.initials: FB
authors.lastname: Casson
authors.affiliation: Département de biochimie et génétique, CHU, Angers, France, Groupe de biologie spécialisée de la Société française de médecine nucléaire, Paris, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Moal
authors.affiliation: Département de biochimie toxicologie pharmacologie, CHRU, Grenoble, France, Groupe de biologie spécialisée de la Société française de médecine nucléaire, Paris, France.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Gauchez
authors.affiliation: Département de biochimie et pharmacologie toxicologie, CHU, Brest, France, Groupe de biologie spécialisée de la Société française de médecine nucléaire, Paris, France.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Moineau
authors.affiliation: Laboratoire Biomnis, Lyon, France, Groupe de biologie spécialisée de la Société française de médecine nucléaire, Paris, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Sault
authors.affiliation: Unité de biologie cellulaire, Hôpital Saint-Louis, AP-HP, Paris, France, Groupe de biologie spécialisée de la Société française de médecine nucléaire, Paris, France.
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Schlageter
authors.affiliation: Laboratoire d'hormonologie, Service de biochimie-toxicologie, CHU de Pontchaillou, Rennes, France, Centre d'investigation clinique plurithématique, Inserm 1414, CHU de Pontchaillou, Rennes, France, Groupe de biologie spécialisée de la Société française de médecine nucléaire, Paris, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Massart
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D044963:Biopsy, Fine-Needle; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000592:standards*; D013954:Thyroglobulin / Q000032:analysis*; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D013954:Thyroglobulin
keywords: differentiated thyroid cancer; fine-needle-aspiration; non-specific adsorption; thyroglobulin; washout