Cardiac Biomarkers
Cardiac Biomarkers
- Which of the following is the most specific marker for myocardial infarction?
A. CK-MB
B. Myoglobin
C. LDH
D. Troponin I
Explanation: Troponin I is the most specific and sensitive biomarker for myocardial infarction. It rises within 4–6 hours and remains elevated for up to 10 days. - Which biomarker rises earliest after myocardial injury?
A. Myoglobin
B. Troponin T
C. CK-MB
D. LDH
Explanation: Myoglobin is the earliest marker to rise (within 1–3 hours), but it is not specific for cardiac muscle. - CK-MB levels typically return to normal within how many hours post-MI?
A. 12–24 hours
B. 24–48 hours
C. 48–72 hours
D. 72–96 hours
Explanation: CK-MB rises in 4–6 hours and returns to normal within 48–72 hours, making it useful to detect reinfarction. - Which cardiac biomarker is useful in detecting reinfarction within a few days of an initial MI?
A. Troponin I
B. LDH
C. Myoglobin
D. CK-MB
Explanation: CK-MB returns to baseline faster than troponins, making it helpful for detecting reinfarction. - Which of the following is NOT a cardiac-specific isoenzyme?
A. CK-MB
B. Troponin T
C. LDH-1
D. Myoglobin
Explanation: Myoglobin is present in both cardiac and skeletal muscle, thus not cardiac-specific. - BNP and NT-proBNP are primarily used to assess:
A. Myocardial infarction
B. Valvular regurgitation
C. Heart failure
D. Pericarditis
Explanation: BNP and NT-proBNP are released in response to ventricular stretch and are primarily used to diagnose and monitor heart failure. - LDH isoenzyme pattern showing a flipped ratio (LDH1 > LDH2) indicates:
A. Liver injury
B. Skeletal muscle damage
C. Myocardial infarction
D. Renal failure
Explanation: A flipped LDH pattern (LDH1 > LDH2) is classic for myocardial infarction. - Which biomarker remains elevated the longest after myocardial infarction?
A. CK-MB
B. Myoglobin
C. Troponin I
D. LDH
Explanation: Troponin I may remain elevated for 7–10 days post-MI, longer than other markers. - Troponin elevation without rise in CK-MB may occur in:
A. Non-cardiac chest pain
B. Early MI
C. Renal failure
D. Hyperkalemia
Explanation: Renal failure may cause elevated troponins due to reduced clearance, even without CK-MB rise. - The use of high-sensitivity Troponin assays is primarily intended to:
A. Differentiate between NSTEMI and STEMI
B. Diagnose myocarditis
C. Detect very low levels of cardiac injury early
D. Monitor anticoagulation
Explanation: High-sensitivity troponin assays help detect even small degrees of myocardial injury early and with greater accuracy. - Which of the following is NOT elevated in stable angina?
A. Troponin I
B. CK-MB
C. Myoglobin
D. All of the above
Explanation: In stable angina, there is no myocardial necrosis, hence cardiac biomarkers like troponin and CK-MB remain normal. - Which marker is least specific for myocardial infarction?
A. Myoglobin
B. Troponin I
C. CK-MB
D. LDH-1
Explanation: Myoglobin is the earliest marker to rise but is found in both cardiac and skeletal muscle, making it non-specific. - Which troponin is more cardiac specific?
A. Troponin T
B. Troponin I
C. Troponin C
D. All are equal
Explanation: Troponin I is more specific to cardiac muscle than Troponin T or C. - Which enzyme is found in highest concentration in heart muscle?
A. LDH
B. CK
C. AST
D. Troponin
Explanation: AST is present in cardiac tissue but is also found in liver and skeletal muscle; CK and LDH are also abundant, but CK-MB is heart-specific. - Which of the following conditions can cause elevated troponins besides MI?
A. Renal failure
B. Sepsis
C. Pulmonary embolism
D. All of the above
Explanation: Elevated troponins may occur in critically ill patients due to non-coronary causes such as renal failure, sepsis, and PE. - Which cardiac biomarker is most useful in diagnosing perioperative MI?
A. Myoglobin
B. Troponin I
C. CK
D. LDH
Explanation: Troponin I remains the most sensitive and specific marker, especially in the setting of surgery where CK can be elevated from muscle injury. - What is the peak time of CK-MB after acute MI?
A. 1–3 hours
B. 3–6 hours
C. 12–24 hours
D. 48 hours
Explanation: CK-MB typically peaks around 12–24 hours after onset of myocardial infarction. - Which biomarker returns to baseline the fastest?
A. Myoglobin
B. CK-MB
C. Troponin I
D. LDH
Explanation: Myoglobin rises early and also returns to baseline quickly—usually within 24 hours. - Which cardiac biomarker is released from necrotic myocytes?
A. BNP
B. CRP
C. IL-6
D. Troponin T
Explanation: Troponin T is a structural protein released from necrotic cardiac myocytes and is highly specific to myocardial injury. - Which of the following is a marker of heart failure severity?
A. NT-proBNP
B. Troponin I
C. CK-MB
D. CRP
Explanation: NT-proBNP is released by ventricular myocardium in response to pressure or volume overload and is used to assess severity and prognosis in heart failure. - What is the typical half-life of troponin I in the bloodstream?
A. 1 hour
B. 6 hours
C. 20 hours
D. 72 hours
Explanation: The biological half-life of troponin I is approximately 20 hours, though it remains detectable for several days due to slow clearance. - Which of the following biomarkers is most elevated in rhabdomyolysis?
A. LDH
B. Troponin I
C. CK-MM
D. BNP
Explanation: CK-MM is the isoenzyme of creatine kinase found predominantly in skeletal muscle and is markedly elevated in rhabdomyolysis. - Which test differentiates between cardiac and skeletal muscle damage?
A. CK total
B. LDH
C. AST
D. CK-MB
Explanation: CK-MB is more specific to cardiac muscle than CK-MM, making it useful in distinguishing cardiac from skeletal muscle damage. - Which biomarker may help in diagnosing reinfarction?
A. Troponin T
B. CK-MB
C. BNP
D. LDH-1
Explanation: CK-MB normalizes within 2–3 days and can rise again with reinfarction, unlike troponins that remain elevated for longer. - What type of molecule is troponin?
A. Enzyme
B. Hormone
C. Cytokine
D. Structural protein
Explanation: Troponin is a structural protein involved in cardiac and skeletal muscle contraction. - Which cardiac marker is commonly elevated in chronic kidney disease without MI?
A. Troponin T
B. CK-MB
C. Myoglobin
D. LDH
Explanation: Troponin T may be chronically elevated in CKD patients due to decreased clearance and ongoing myocardial strain. - BNP is most useful in the diagnosis of:
A. Acute coronary syndrome
B. Pericarditis
C. Myocarditis
D. Congestive heart failure
Explanation: BNP and NT-proBNP are released in response to ventricular stretch and volume overload, making them key biomarkers in diagnosing CHF. - Which of the following has the longest detection window after MI?
A. Myoglobin
B. CK-MB
C. Troponin I
D. AST
Explanation: Troponin I may remain elevated for up to 10 days post-MI, offering a long diagnostic window. - Which inflammatory marker is often elevated in acute coronary syndromes?
A. CRP
B. BNP
C. Troponin T
D. CK-MB
Explanation: C-reactive protein (CRP) is a nonspecific marker of inflammation and is often elevated in unstable angina and other acute coronary syndromes. - The primary role of troponin in muscle physiology is:
A. Provide energy for contraction
B. Bind oxygen for mitochondria
C. Initiate ATP breakdown
D. Regulate actin-myosin interaction
Explanation: Troponin regulates contraction by controlling actin and myosin interactions in striated muscle fibers.
| 🩺 Points 1–15 | 🩺 Points 16–30 |
|---|---|
| 1. Troponins are the most specific markers for MI. | 16. Troponin I is preferred for diagnosing perioperative MI. |
| 2. Myoglobin rises earliest after MI but lacks specificity. | 17. CK-MB peaks at 12–24 hours after infarction. |
| 3. CK-MB helps diagnose reinfarction due to short half-life. | 18. Myoglobin returns to baseline within 24 hours. |
| 4. Troponin I is more cardiac-specific than Troponin T. | 19. Troponin T is released from necrotic myocytes. |
| 5. Troponins remain elevated for 10–14 days post-MI. | 20. NT-proBNP reflects severity of heart failure. |
| 6. BNP is useful in diagnosing heart failure. | 21. Troponin I has a half-life of ~20 hours. |
| 7. Troponin can be elevated in CKD without MI. | 22. CK-MM is elevated in rhabdomyolysis. |
| 8. Troponin T is a structural cardiac protein. | 23. CK-MB distinguishes cardiac from skeletal muscle injury. |
| 9. LDH-1 is elevated in late MI presentations. | 24. CK-MB helps in diagnosing reinfarction. |
| 10. CK-MB peaks at 12–24 hours post-MI. | 25. Troponin is a structural, not enzymatic, protein. |
| 11. Biomarkers are not elevated in stable angina. | 26. Troponin T may be chronically elevated in CKD. |
| 12. Myoglobin is the least specific cardiac biomarker. | 27. BNP is most useful in diagnosing CHF. |
| 13. Troponin I has greater specificity than Troponin T. | 28. Troponin I has the longest detection window post-MI. |
| 14. CK is abundant in heart; CK-MB is more specific. | 29. CRP is an inflammatory marker elevated in ACS. |
| 15. Troponins can rise in non-MI causes (e.g. sepsis). | 30. Troponin regulates actin-myosin interaction. |
| # | Key Point | # | Key Point |
|---|---|---|---|
| 1 | Troponins are the most specific markers for MI. | 16 | Troponin I is preferred for perioperative MI. |
| 2 | Myoglobin rises early but lacks specificity. | 17 | CK-MB peaks 12–24 hrs post-MI. |
| 3 | CK-MB is useful in detecting reinfarction. | 18 | Myoglobin normalizes within 24 hrs. |
| 4 | Troponin I is more specific than T. | 19 | Troponin T is released from necrotic myocytes. |
| 5 | Troponins stay elevated for 10–14 days. | 20 | NT-proBNP indicates HF severity. |
| 6 | BNP is a heart failure marker. | 21 | Troponin I half-life is ~20 hrs. |
| 7 | Troponins may rise in CKD without MI. | 22 | CK-MM is elevated in rhabdomyolysis. |
| 8 | Troponin T is a structural protein. | 23 | CK-MB differentiates cardiac vs skeletal injury. |
| 9 | LDH-1 is elevated late post-MI. | 24 | CK-MB can detect reinfarction. |
| 10 | CK-MB peaks at 12–24 hrs. | 25 | Troponin is a structural, not enzymatic protein. |
| 11 | Stable angina doesn’t elevate biomarkers. | 26 | Troponin T remains high in CKD. |
| 12 | Myoglobin is the least specific marker. | 27 | BNP aids diagnosis of CHF. |
| 13 | Troponin I is highly myocardium-specific. | 28 | Troponin I stays detectable longest post-MI. |
| 14 | CK is in heart; CK-MB adds specificity. | 29 | CRP is elevated in ACS. |
| 15 | Troponin may rise in non-MI conditions. | 30 | Troponin regulates actin-myosin interaction. |
