Skeletal Muscle Biomarkers in Heart Disease

Abstract

On the other hand, methods on the market are nonstandardized, causing significantly different 99th percentile limits across the cTn assays [6]. Heterogeneity between assays is caused by the use of different antibodies for capture and detection of circulating cTn forms. A practical and convenient approach to deal with these differences has been proposed by Apple [6]. One of the factors taken into account in his scorecard for individual cTn assays is the analytical criterion recommended by the international guidelines, which requires a total imprecision equal to or less than 10% at the 99th percentile value [1,2]. Assays that are compatible with this requirement are designated as ‘guideline acceptable’. Using 20% as the maximal acceptable imprecision excludes a contemporary assay from clinical use, and assays with an imprecision between 10 and 20% are indicated as ‘clinically usable’ [6]. Another analytical issue that is important for clinical interpretation of cTn results is the impact of interferences. For example, human antimouse antibodies and rheumatoid factor cause falsely increased cTn, while anti-cTn autoantibodies cause falsely decreased cTn [7,8]. The influence of hemolysis appears to be method dependent, as it has been reported to increase cTnI on Vitros ECi (Ortho-Clinical Diagnostics) and to decrease cTnT on Roche instruments [9].