Cardiac Enzymes Flashcards
How do you distinguish between a STEMI and NSTEMI?
EKG
How do you distinguish between UA and NSTEMI?
Cardiac Enzymes
What are cardiac enzymes?
When there is an infarction of myocardial cells the membrane integrity is disrupted causing leaking of macromolecules into the peripheral circulation where they are detected.
Ideal Biomarker Requirements:
- High Specificity
- High Sensitivity
- Release and Clearance kinetics provide expedient diagnosis
- Measured level is in direction proportion to the extent of myocardial injury
- Commercially available, easy to perform
This cardiac enzyme is highly specific and sensitive for MI.
It will rise in 3-12 hours
Peak at 24 hours
Return to normal in 5-14 days
Troponin I
This cardiac enzyme is highly specific and sensitive for MI.
It will rise in 3-12 hours
Peak at 12-48 hours
Return to normal in 5-14 days
Troponin T
When are troponin levels more beneficial?
6+ hours post-MI
When do you need to reassess Troponin?
6-12 hours after symptoms began
T/F: Troponin levels are not useful for late diagnosis of MI
False, they are useful.
Negative Troponin Test indicates:
Low Risk of Death or MI within 30 days
Positive Troponin Test indicates:
Strong Independent Predictor of Mortality and Serious Adverse Outcomes
Tropinin turn around time?
9-12 minutes
If a patient comes in with ACS symptoms, regardless of EKG findings, if there are negative troponins at least twice, how would we categorize this?
Unstable Angina
If a patient comes in with ACS symptoms, ST/T Abnormalities (not Elevation) EKG findings, if there are positive troponins at least once, how would we categorize this?
NSTEMI
Causes of Troponin Elevation other than MI
- CHF
- Tachyarrhythmia, heart block
- Endurance Exercise
- Cardiomyopathy (CM)
- Myocarditis, Pericarditis
- Blunt Chest Trauma
- Pulmonary Embolism
- Renal Failure
- Severe Sepsis
- Aortic Valve Disease
- CVA
- Cardiotoxic Drugs
This enzyme is found in multiple places throughout the body, including: brain, lungs, GI, skeletal and cardiac muscle. It is subdivided into different groups.
Normal Range:
Creatine Kinase
CK found in brain, lungs, and GI
CK-BB
CK found predominantly in cardiac muscle and some skeletal muscle
CK-MB
CK found in skeletal and cardiac muscle
CK-MM
______ of CK increases diagnostic specificity.
Fractionation
This is the most specific of the CKs for cardiac muscle.
It rises in 3-12 hours
Peaks at 24 hours
Returns to Baseline in 2-3 days
CK-MB
False Positives of CK-MB could be due to
- Trauma
- Skeletal Muscle Injury
- Surgical Procedures
What is better than CK-MB testing the same thing?
Monoclonal Antibody Assays (More accurate)
How do you calculate the Relative Index for CK-MB?
[Measure CK-MB (ng/mL) x 100]/Total CK Activity (IU/L)
