Performance evaluation of an automated electrochemiluminescent calcitonin (CT) immunoassay in diagnosis of medullary thyroid carcinoma

Objectives: The aim was to evaluate the Elecsys (R) hCT electrochemiluminescence immunoassay on the immunoanalyser Cobas e411. Design and methods: Within-run, between-run imprecision, linearity, recovery after dilution, the high dose hook effect, as well as the stability of calcitonin were examined. A method comparison to an established immunoradiometric assay was executed in 135 routine plasma samples. Results: Within- and between-run imprecision CVs were <= 1.4% and <= 2.5%, respectively. The Elecsys (R) hCT assay was linear over the measuring range of 0.5-2000 ng/L. Recoveries after dilution of a high sample in Diluent MultiAssay were within the range of 95% to 97%. The high dose hook point occurred at an hCT concentration of 56,000 ng/L. Calcitonin was found to be stable up to 5 h at RT, up to 24 h at 2-8 degrees C and up to one month at -20 degrees and -80 degrees C. Passing Bablok regression analysis showed no significant deviation from linearity (p = 0.10) with a slope of 1.00 (95% CI 0.95-1.06) and an intercept of -0.81 (95% CI -1.01 to -0.46). Conclusions: The Elecsys (R) hCT immunoassay provides precision and reliability in combination with reduced turnaround time as compared to the hCT IRMA. (C) 2016 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.