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Clin Chem Lab Med. 2019 Jan 10. pii: /j/cclm.ahead-of-print/cclm-2018-1100/cclm-2018-1100.xml. doi: 10.1515/cclm-2018-1100. [Epub ahead of print]

Sample matrix and high-sensitivity cardiac troponin I assays.

Author information

1
McMaster University, Hamilton, ON, Canada.
2
Core Laboratory, Hamilton Health Sciences, Hamilton, ON, Canada.
3
Juravinski Hospital and Cancer Centre, 711 Concession Street, Hamilton, ON L8V 1C3, Canada, Phone: +905-521-2100.
4
Clinical Research Laboratory and Biobank, Hamilton Health Sciences, Hamilton, ON, Canada.
5
Mayo Clinic, Rochester, MN, USA.

Abstract

Background Manufacturers of high-sensitivity cardiac troponin (hs-cTn) assays have restricted use of what sample types or matrices are acceptable to use for measurement. Our goal was to evaluate the comparability of the Siemens ADVIA Centaur hs-cTnI assay across different matrices and under different storage conditions. Methods Three different QC-plasma matrices were evaluated for imprecision <10 ng/L. Passing-Bablok regression and difference plots were determined for cTnI concentrations spanning the reference interval (limit of quantification to male 99th-percentile: 2.5 ng/L to <60 ng/L) between serum and lithium heparin plasma, lithium heparin and EDTA plasma and between the Siemens and Abbott hs-cTnI assays. Stability at room temperature (RT) and 2-8 °C was also assessed across the three matrices. Results Over 16-weeks the SDs were ≤1.0 ng/L for QCs ranging from 5.0 to 8.3 ng/L. Across the reference interval there was excellent agreement between lithium heparin plasma and serum for the Siemens hs-cTnI assay (slope=0.98/intercept=-0.1), however, cTnI concentrations were proportionally lower in EDTA as compared to lithium heparin plasma (slope=0.90, 95% CI: 0.88-0.92). In lithium heparin plasma the Siemens hs-cTnI concentrations were higher than the Abbott hs-cTnI concentrations (slope=1.26/intercept=-0.2). Stability of cTnI in lithium heparin plasma as compared in serum and EDTA plasma appeared more labile, with decreases ≥20% in concentrations evident as early as 1-day in storage at RT. Conclusions There is excellent agreement in concentrations between lithium heparin plasma and serum with the Siemens ADVIA Centaur hs-cTnI assay; however, cTnI concentrations in EDTA plasma are lower. Reference intervals and clinical studies in EDTA plasma for the Centaur hs-cTnI assay are required before clinical use.

KEYWORDS:

EDTA plasma; analytical variation; high-sensitivity cardiac troponin; lithium heparin plasma; matrix; serum; stability

PMID:
30838842
DOI:
10.1515/cclm-2018-1100

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