Interpreting troponin in chronic kidney disease
Learn about the influence of chronic kidney disease on troponin levels.
Troponin is a useful biomarker to track in patients who've experienced acute coronary syndrome. In this video, from our Cardiology Lab Essentials course, you'll learn about the influence of chronic kidney disease on troponin levels and how to interpret these levels in order to support your overall patient management plan.
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[00:00:00] In patients with chronic kidney disease, diagnosing acute myocardial infarction is much more challenging than in a general population. This is because some cardiac biomarkers act differently when renal function is impaired. So, how can we use cardiac lab markers in chronic kidney disease or CKD for short? Even in the absence of any clinical evidence of myocardial damage, troponin elevations are pretty common in patients with CKD, especially
[00:00:30] as renal impairment progresses. Today, it is clear that these elevations are not caused solely by the impaired renal function and decreased renal clearance but that chronic myocardial injury or structural heart disease also contribute to troponin elevation in these patients. Furthermore, we know that stably elevated cardiac troponin concentrations in CKD patients are associated with a poor long-term survival. Interestingly, it was observed that cardiac troponin I
[00:01:00] is less often elevated than comparison to troponin T, so some advocate the use of troponin I testing in CKD patients. However, with increasing sensitivity of tests, these differences diminish. So, what should you do if you suspect your CKD patient, with chronic troponin elevations, of having an acute myocardial infarction? Can you still use cardiac biomarkers to diagnose an acute myocardial infarction? The good news is, yes, you can. As with diagnostic criteria for individuals
[00:01:30] with no renal impairment, troponin is the preferred marker for diagnosing myocardial infarction and it is crucial to not rely on one single measurement but instead to use serial measurements and to interpret the changes in troponin levels. This will improve the specificity of your results. In patients with chronically elevated troponin levels, at or above the upper reference limit, a greater than 20% increase in serially measured troponin is generally recommended
[00:02:00] as an acceptable threshold for an acute MI, of course, along with appropriate clinical presentation. What about dialysis? Does dialysis have an impact on troponin levels? There are controversial results from studies addressing this question. Although it is best to consider the timing of dialysis when interpreting your lab results, dialysis does not alter diagnostic criteria. So, what are the take-home messages? First, don't ignore changes in troponin in patients with chronic kidney disease.
[00:02:30] These increase troponin levels may represent myocardial damage. You should definitely check for coronary heart disease. And second, large changes require fast action. If you suspect myocardial infarction and your patient already had increased troponin levels before, check for change of more than 20% in troponin levels, in serial measurements.