Cardiac troponins in the intensive care unit: common causes of increased levels and interpretation

BACKGROUND AND OBJECTIVES: Clinical chemistry is an important component of the diagnosis of many conditions, and advances in laboratory science have brought many new diagnostic tools to the intensive care unit clinician, including new biomarkers of cardiac injury like troponin T and I. Interpretation of these clinical laboratory results requires knowledge of the performance of these tests. SETTING AND PATIENTS: This article reviews the interpretation and performance of diagnostic markers of myocardial injury in patients with diverse clinical conditions of interest to critical care practitioners. CONCLUSIONS: Cardiac troponin I and T, regulatory components of the contractile apparatus, are sensitive indicators of myocardial injury and have become central to the diagnosis of myocardial infarction. The troponins are also released in a number of clinical situations in which thrombotic complications of coronary artery disease and resultant acute myocardial infarction have not occurred. These situations include conditions like pulmonary embolism, sepsis, myocarditis, and acute stroke. Elevated troponins in these conditions are thought to emanate from injured myocardial cells and, in most circumstances, have been associated with adverse outcomes. Practitioners should be mindful of the wide spectrum of diseases that may result in elevated troponin when interpreting these measurements.