What is the relationship between cardiac troponin elevation and Acute Kidney Injury (AKI)?

From the Guidelines

Cardiac troponin elevation can occur in acute kidney injury (AKI) even in the absence of acute coronary syndrome, and clinicians should consider the clinical context and look for dynamic changes in troponin levels to distinguish between cardiac damage and kidney dysfunction. This relationship is important to understand because troponin is primarily used as a marker for myocardial injury, but its levels can be falsely elevated in patients with impaired kidney function 1. In AKI, troponin levels may rise due to decreased renal clearance of the molecule, rather than from actual cardiac damage. Additionally, the uremic state in AKI can cause direct myocardial injury through inflammation, oxidative stress, and electrolyte abnormalities, leading to genuine troponin release.

When interpreting troponin levels in patients with AKI, clinicians should consider the following key points:

• Look for dynamic changes in troponin levels rather than single values
• Correlate findings with other cardiac tests like ECG and echocardiography
• Serial measurements showing a rising and falling pattern are more suggestive of acute myocardial injury
• Persistently elevated levels without significant changes may reflect the kidney dysfunction This distinction is crucial for appropriate management decisions, as misinterpreting troponin elevation in AKI could lead to unnecessary cardiac interventions 1.

It is also important to note that troponin elevations can be due to various non-cardiac conditions, such as tachyarrhythmia, hypotension or hypertension, cardiac trauma, acute heart failure, myocarditis and pericarditis, acute pulmonary thromboembolic disease, and severe non-cardiac conditions such as sepsis, burns, respiratory failure, acute neurological diseases, and drug toxicity 1. Chronic elevations can result from structural cardiac abnormalities such as left ventricular hypertrophy or ventricular dilatation and are also common in patients with renal insufficiency.

In the diagnosis of acute myocardial infarction, a rise and/or fall in troponin values with at least one value above the decision level is required, coupled with a strong pre-test likelihood 1. The demonstration of a rising and/or falling pattern is needed to distinguish acute- from chronic elevations in troponin concentrations that are associated with structural heart disease. Therefore, clinicians should prioritize the clinical context and dynamic changes in troponin levels when interpreting troponin elevation in AKI, rather than relying solely on single values or absolute levels.

From the Research

Relationship between Cardiac Troponin Elevation and AKI

• Cardiac troponin elevation is a common occurrence in patients with acute kidney injury (AKI) 2, 3, 4.
• The diagnostic reliability of cardiac troponins is suboptimal in patients with kidney disease due to possible decreased clearance of troponin with acute and chronic kidney impairment 2.
• Troponin concentrations rise and fall with acute kidney injury and its recovery, limiting their use in the diagnosis of acute coronary syndromes (ACS) 2.
• High-sensitivity troponins can confirm or exclude a diagnosis of ACS in the emergency room in a significant proportion of kidney disease patients 2.
• Statistically significant factors associated with elevated troponin levels in AKI patients include age over 60 years, abnormal electrocardiogram, and history of previous ischemic heart disease 3.
• AKI induces high-sensitivity troponin measurement changes after cardiac surgery, with a significant sustained rise in the AKI group compared to the non-AKI group 4.

Pathophysiology and Management of AKI

• AKI is a heterogeneous syndrome that affects acute morbidity and mortality, as well as a patient's long-term prognosis 5, 6.
• Prevention of AKI focuses on fluid management, kidney perfusion pressure, and the choice of vasopressor 6.
• Supportive treatment of AKI includes appropriate volume control, nephrotoxic drug management, and the timing and type of kidney support 5.
• Post-AKI risk of long-term sequelae includes incident or progression of chronic kidney disease, cardiovascular events, and mortality 5, 6.

Diagnostic Value of Troponin in AKI

• The diagnostic value of high-sensitivity troponin T (hsTnT) is explored in the settings of cardiac surgery-induced AKI, showing a significant sustained rise in the AKI group compared to the non-AKI group 4.
• The use of hsTnT can help confirm or exclude a diagnosis of ACS in kidney disease patients, despite the limitations of troponin measurements in AKI patients 2, 4.