Lab

Serum Cardiac Marker

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Serum Cardiac Marker, Cardiac Marker

  • See Also
  • Indications
  • Protocol
  • Typical
  1. Troponin I or Troponin T at presentation and 3 hours later
  2. May extend Troponin Timing to every 4 to 6 hours for 3 samples
  3. Trend upward above discriminatory Troponin values suggests acute Myocardial Infarction
  4. Older protocols using CK and CK-MB have largely been replaced by Troponins
  • Protocol
  • Troponin and CK-MB with 2 hour intervals (older protocol)
  1. Initial tests at presentation
    1. Troponin I or Ultrasensensitive Troponin T
    2. CK and CK-MB
  2. Tests at 2-4 hours after initial labs
    1. Troponin I
    2. CK and CK-MB
  3. Interpretation: Case in which acute Myocardial Infarction unlikely
    1. Initial Ultrasensitive Troponin T negative or
    2. Second Troponin I negative and CK-MB not increasing
  4. References
    1. Weingart in Majoewsky (2012) EM:RAP 12(4): 6-7
  • Protocol
  • Troponin and CK-MB every 8 hours for 3 samples (older protocol)
  1. Protocol
    1. Obtain Troponin at 0 hours, 8 hours and 16 hours
      1. Primary Cardiac Marker: Specific for cardiac event
      2. Not useful for monitoring event extension
        1. Levels stay elevated for 14 days
    2. Obtain CK-MB at 0 hours, 8 hours, and 16 hours
      1. Primary purpose: Follow cardiac event extension
      2. Decreases more rapidly than Troponin after event
  2. Test Sensitivity of combined protocol
    1. Test Sensitivity: >98% at 8 hours
    2. Test Specificity: 80 to 95% at 8 hours
  3. References
    1. Jernberg (2000) Am J Cardiol 86:1367-71 [PubMed]
  1. Rises: 3-6 hours (up to 10 hours)
  2. Peaks: 12-48 hours
  3. Duration: 4-10 days
  4. Subunits
    1. Troponin T
    2. Troponin I
  1. Rises: 4-6 hours
  2. Peaks: 12-24 hours
  3. Duration: 4-5 days
  4. Subunits (Fractionate to CK-MB only if CPK increased)
    1. CK-MB Fraction (duration for 2-3 days)
    2. CK-MB over 5% of total CPK suggests Myocardial Injury
  • Labs
  • Myoglobin
  1. Advantage: First Cardiac Marker to increase
  2. Disadvantage: Poor Specificity (only helps if negative)
  3. Rises: 1-2 hours
  4. Peaks: 4-6 hours
  5. Duration: 1-2 days
  1. Peaks: 24-36 hours
  2. Duration: 5 days
  1. Peaks: 24-48 hours
  2. Duration: 14 days
  1. Predicts adverse events in Unstable Angina
  2. Morbidity and mortality increase with increased WBCs
    1. WBC Count >10,000: High risk of adverse event
    2. WBC Count >15,000: Very high risk of adverse event
  3. References
    1. Cannon (2001) Am J Cardiol 87:636-9 [PubMed]