Cardiac troponin assays have gone through a tremendous evolution since they were introduced into clinical labs in 1995 until the most recent ultra-sensitive assays became prevalent in 2007. The original troponin T (TnT) and troponin I (TnI) assays had a cut-off value of 1.5 ng/mL in 1995. With this original assay, the troponin levels would typically become elevated about 7 hours after the onset of chest pain from ACS. In 2003, a more sensitive cardiac troponin T (cTnT) and cardiac troponin I (cTnI) test was developed with a cut-off value of 0.1 ng/mL and would typically become elevated about 2-3 hours after the onset of ACS symptoms. In 2007, the ultra-sensitive cardiac troponin T (cTnT-ultra) and cardiac troponin I (cTnI-ultra) test was developed with a cut-off value of 0.04 ng/mL. This ultra-sensitive cTnT and cTnI test can become elevated less than two hours after the onset of ACS symptoms.
This ultra-sensitive TnI test can help to make a faster diagnosis of ACS; however, it is so sensitive that it can be elevated from many other cardiac disorders and non-cardiac disorders. I caution all hospitals to be wary of this to avoid unnecessary hospital admissions for “troponinemia” to “rule out MI” or “rule out ACS.” I caution all hospitals to avoid having a cardiac troponin test as part of an “ER panel” for blood work just as I would avoid having a D-dimer as part of an “ER panel”. This way you will avoid unnecessary testing for patients presenting to the ER for complaints that are obviously not related to the heart such as ankle or knee pain.
The following is a list of all the cardiac and non-cardiac causes of troponinemia:
Non-cardiac Causes of Increased Troponin Levels
- Renal failure
- Pulmonary embolism
- Severe pulmonary hypertension
- Sepsis
- Severe critical illness
- Burns
- Extreme exertion
- Amyloidosis or other infiltrative diseases
- Stroke and subarachnoid hemorrhage
Cardiac Causes of Elevated Troponin (besides ACS)
- Acute and chronic heart failure
- Myocarditis
- Cardiac contusion from trauma
- Cardioversion
- Endomyocardial biopsy
- Aortic dissection
- Hypertrophic cardiomyopathy
- Aortic valve disease (aortic stenosis or regurgitation)
- Cardiotoxic drugs
- Tachyarrhythmia (SVT, V-tach, atrial fibrillation)
- Bradyarrhythmia or heart block
- Cardiac surgery
- Cardioversion
- Tako-tsubo cardiomyopathy
- Rhabdomyolysis
- Stenting or angioplasty (percutaneous coronary intervention/PCI)
