Troponin I

A value of 0.04 ng/mL is the 99th percentile value for a healthy population.

Clinical Interpretation

The 99th percentile concentration for the Beckman High Sensitivity Troponin assay is 0.03 ng/mL. According to current consensus guidelines (Newby 2012), troponin results that exceed the 99th percentile concentration are strongly suggestive of cardiac injury, which can be from many causes (see below for examples). For troponin concentrations 0.40 ng/mL and higher, the underlying cardiac injury is usually a myocardial infarction. Troponin concentrations of 0.04-0.39 ng/mL require serial troponin measurements and clinical correlation to interpret, as further described in the guidelines. Note that a more precise assay was implemented on Dec 1, 2019.

Partial list of non-ischemic causes of elevated troponin (myocardial damage)

• Heart Failure
• Pulmonary Embolism
• Chronic Kidney Disease
• Sepsis
• Chemotherapy-Associated Cardiac Toxicity
• Cardiotoxicity of Other Drugs
• Cocaine Use
• Infection and Myocarditis
• Myopericarditis
• Myocardial contusion

Frequently Asked Questions Regarding the Use of Troponin (Adapted from Newby 2012, Table 3)

What does an elevated troponin level mean?

• Elevated troponin is a sensitive and specific indication of myocardial damage, with troponin release from myocytes into the systemic circulation.
• In and of itself, elevated troponin does not indicate myocardial infarction (myonecrosis due to ischemia); rather, it is nonspecific relative to the etiology of myocardial damage.
• Troponin elevation occurs in many nonischemic clinical conditions (see above).

When should a troponin level be obtained?

• Because an elevated troponin concentration is not specific for myocardial infarction, troponin evaluation to rule out myocardial infarction should be performed only if clinically indicated.
• An elevated troponin level must always be interpreted in the context of the clinical presentation and pre-test likelihood that it represents myocardial infarction.
• Troponin is recommended for diagnosis of myocardial infarction in chronic kidney disease patients with symptoms of myocardial infarction (regardless of the severity of renal impairment). A rise or fall in troponin values of ≥20% over 6 to 9 h should be used to define acute myocardial infarction in end-stage renal disease patients.

What is the prognostic significance of an elevated troponin level?

• Troponin elevation imparts a worse prognosis, irrespective of the underlying etiology.
• For patients with non-ST-segment elevation acute coronary syndrome, global risk assessment, rather than any single risk marker, best informs prognosis and is preferred to guide therapeutic decisions.