Sample matrix and high-sensitivity cardiac troponin I assays

Area of Science:

• Clinical Chemistry
• Biomarker Analysis
• Diagnostic Assay Validation

Background:

• High-sensitivity cardiac troponin (hs-cTn) assays have specific sample matrix requirements.
• Evaluating assay performance across various sample types is crucial for clinical adoption.

Purpose of the Study:

• To assess the comparability of the Siemens ADVIA Centaur hs-cTnI assay across different sample matrices (serum, lithium heparin, EDTA plasma).
• To evaluate the stability of hs-cTnI in these matrices under different storage conditions.

Main Methods:

• Imprecision testing for three QC-plasma matrices.
• Passing-Bablok regression and difference plots for serum vs. lithium heparin, lithium heparin vs. EDTA plasma, and Siemens vs. Abbott hs-cTnI assays.
• Stability assessment at room temperature and 2-8 °C.

Main Results:

• Excellent agreement between lithium heparin plasma and serum for the Siemens assay (slope=0.98).
• Lower cTnI concentrations observed in EDTA plasma compared to lithium heparin plasma (slope=0.90).
• Siemens assay showed higher cTnI concentrations than Abbott assay in lithium heparin plasma (slope=1.26).
• hs-cTnI in lithium heparin plasma demonstrated greater lability at room temperature compared to serum and EDTA.

Conclusions:

• The Siemens ADVIA Centaur hs-cTnI assay demonstrates excellent agreement between serum and lithium heparin plasma.
• EDTA plasma results in lower cTnI concentrations, necessitating specific reference intervals and clinical validation.
• Further studies are required for the clinical use of the Centaur hs-cTnI assay with EDTA plasma.