Reporting of Cardiac Troponin Concentrations

Abstract

There is currently substantial debate about how cardiac troponin concentrations should be reported. We would like to offer an alternative strategy to two recent recommendations. In a recent editorial, Apple and Wu (1) proposed that the concentration of cardiac troponin that corresponds to an analytical imprecision (CV) of 10% be used as a medical diagnostic guide. Panteghini et al. (2), in their document on quality specifications for cardiac troponin assays, state that “the detection limit … of cardiac troponin … should be significantly lower than the clinical discrimination limit used”. The main reason for this is that patient risk stratification based on results generated by assays not meeting this requirement would be compromised by considerable imprecision. In contrast, a recent article on the proposed new definition of myocardial infarction states that “A review of currently available data demonstrates no discernible threshold below which an increased value for cardiac troponin would be deemed harmless” (3). Thus, the first two views (1)(2) focus on ensuring that reported results are real, and the third (3) is intent on extracting the maximum clinically useful information. Is it possible to reconcile these imperatives? Current commercially available assays for cardiac troponin cannot detect the picomolar concentrations of protein that are reportedly present in the blood of healthy persons (4). This point is supported by recent work from Roche Diagnostics in their efforts to establish a reference value for cardiac troponin T. Among 1951 apparently healthy persons, only 19 had troponin T concentrations above the minimum detectable concentration of 0.010 μg/L (Roche Diagnostics, information on file). No information was …