Troponin

Aka: Troponin, Troponin Assay, Increased Troponin Causes, Causes of Abnormal Troponin

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II. Physiology: Dynamics

  1. Rises: 2-4 hours (but may be delayed to 8-12 hours in minor injury)
  2. Peaks: 12-24 hours
  3. Duration: 14 days (in large Myocardial Infarction)

III. Physiology: Subunits

  1. Troponin T
  2. Troponin I
  3. Ultrasensitive Troponin T (hs-cTnT)

IV. Causes: Increased Troponin

  1. Acute Coronary Syndrome (Myocardial Infarction)
    1. Other causes below are referred to as Myocardial Injury or Troponin Leak
  2. Arrhythmia
    1. Atrial Fibrillation with Rapid Ventricular Rate
    2. Supraventricular Tachycardia (15-20% of cases)
  3. Cardiac injury, stress or increased myocardial oxygen demand
    1. Cardiac procedures
    2. Chronic Severe Hypertension
    3. Severe Cardiomyopathy (including Hypertrophic Cardiomyopathy)
    4. Congestive Heart Failure
    5. Myocarditis
    6. Pericarditis
    7. Marathon Running or other strenuous Exercise
    8. Cardiac Contusion
    9. Endocarditis
    10. Arrhythmia (e.g. PSVT, Atrial Fibrillation with RVR)
  4. Non-cardiac conditions
    1. Chronic Renal Failure
    2. Hypoxia
    3. Pulmonary Embolism
    4. Pulmonary Hypertension
    5. Chemotherapy
    6. Cerebrovascular Accident
    7. Subarachnoid Hemorrhage
    8. Aortic Dissection
    9. Burn Injury
    10. Acute Respiratory Distress Syndrome (ARDS)
    11. Sepsis
    12. Severe Anemia
    13. Shock
  5. References
    1. Agewall (2011) Eur Heart J 32(4): 404-11 [PubMed]

V. Approach: Precautions

  1. Obtain Troponin for risk stratification when pretest probability of Acute Coronary Syndrome is high
    1. Ultrasensitive Troponin T has a high False Positive Rate
    2. Positive Troponin In low probability Chest Pain
      1. Subjects that patient to possibly unnecessary stress testing (in some cases angiogram)
  2. Interpret Troponin In context of history, exam and Electrocardiogram
    1. A normal Troponin does not exclude Acute Coronary Syndrome
      1. Negative Troponin does not negate a concerning history or clinical findings
    2. An abnormal Troponin In the absence of other clinical findings does not equal Acute Coronary Syndrome
  3. Compare Troponin level to prior Troponin levels and establish a baseline
    1. Mild chronically elevated Troponin Is common in Chronic Kidney Disease and Congestive Heart Failure
    2. Obtain a second Troponin In 4-6 hours
      1. Establish a trend in mildly elevated Troponin levels despite other reassuring findings
  4. Troponin Increase suggests myocardial cell injury (outside of Chronic Kidney Disease)
    1. First exclude Acute Coronary Syndrome
    2. Next optimize management of conditions with increased myocardial oxygen demand (e.g. CHF, Sepsis)
    3. Finally, consider Troponin Increase a potential marker for worse prognosis in acute presentations (e.g. CVA)
  5. Biotin (High dose, >5000 mcg/day) falsely lowers Troponin

VI. References

  1. Mattu in Majoewsky (2013) EM:Rap 13(9): 5
  2. Ebell (2000) J Fam Pract 49:550-6 [PubMed]
  3. Newby (2012) J Am Coll Cardiol 60(23):2427-63 [PubMed]

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