The measurement of cardiac troponins has become a commonly used biochemical marker for myocardial injury and infarction. Unfortunately, there are several factors that may make the interpretation of troponin values difficult, including spurious elevations that are not indicative of myocardial injury after further evaluation. One of the major clinical confounders, particularly in critically ill patients, is renal insufficiency. Patients with chronic renal insufficiency are known to be at higher risk for developing accelerated atherosclerotic coronary artery disease (CAD), so the ability to interpret biochemical markers for myocardial disease in this population is of great importance. For patients with acute renal insufficiency or failure, there is no similar incremental risk of CAD directly attributable to the renal failure, but myocardial events are nevertheless common in these patients.

Troponins are protein molecules that participate in the regulation of contractile function of the myocardial sarcomeres and are released into the general circulation when myocardial injury occurs much as creatinine kinase–MB (CK-MB) is under similar conditions. There are two troponins: I and T. Elevated troponin T has been shown to correlate with an increased risk of future acute coronary syndromes. For troponin I, this relationship is not as clear, with the study results being contradictory. Some hospitals measure and report troponin I, but many hospital laboratories report troponins as a combined value. The problem with this is that troponin T has been shown to lack specificity for making the diagnosis of an acute coronary event in patients with end-stage renal disease. The exact values for the upper normal limit of troponins may vary from hospital lab to hospital lab based on the assay used. Where the cutoff is set for any particular lab test will determine its specificity and sensitivity and should be optimized using receiver operator curve (ROC) analysis. The preponderance of data suggests that higher thresholds are required for using cardiac troponins to define outcomes for renal patients suspected of having an acute coronary syndrome. ROC analysis suggests that for nonrenal patients, the upper limit should be approximately 0.1 μg/L while for renal patients the upper limit should be approximately 0.5 μg/L, though these values are not absolute. In comparison, most of the data on CK-MB suggest
that values for this analyte do not need to be significantly adjusted for renal patients.