The importance of low level QC for high sensitivity troponin assays

Background: With the advent of the new high-sensitivity troponin assays, it is becoming critical to measure troponin accurately to low concentrations. To ensure assay performance is acceptable, appropriate QC must be run. Methods: In addition to the routine use of commercial QC material, we prepared pools of human QC material with low troponin concentrations close to the limit of quantitation, and ran these regularly on our laboratory analysers. Results: Over 3 years we found no drift or shift in our hs-cTnI assay. We found that only the very low concentration human QC material gave warning of precision problems with the hs-cTnI assay. At the time of the documented poor assay precision, the higher concentration QC material indicated satisfactory performance. Conclusions: Choice of QC material with an appropriate concentration is important for any assay. For hs-cTn assays, it is of particular importance to use control material with a concentration near to the limit of quantitation.