Practicing appropriateness: the case of troponin.

Laboratory testing significantly contributes to the clinical decision making, and the number of tests that a modern clinical laboratory can now perform is considerable. The impact of Laboratory Medicine in Cardiology has substantially evolved and increased over the past years. The cardiac troponin I and T (cTnI and cTnT) are universally regarded as the reference biomarkers for detection of myocardial injury and, understandably, for the diagnosis of myocardial infarction. Novel immunoassays for measurement of cTns have been recently introduced, which are characterized by a considerable improvement of analytical sensitivity and lower imprecision at low concentrations of the proteins. This assays, defined as last generation or high-sensitivity, allow to detect cTn concentrations that were virtually undetectable with the previous methods. On the one hand this has remarkably improved the diagnostic sensitivity for diagnosing myocardial infarction but, on the other, this has reduced the diagnostic specificity. A potential solution of this problem entails diagnostic algorithm based on the serial evaluation of these biomarkers, although the crucial issue still remains the appropriateness of the request. In conclusion, as often occurred in Laboratory Medicine, the leading problem with the use of highly-sensitivity cTn assays is the inappropriateness of ordering and interpretation of test results, and not the biomarker in itself.