A 55-year-old man presents to the emergency department 90 minutes after the onset of chest pain. Which cardiac biomarker is expected to show the EARLIEST detectable rise in serum?
- A Cardiac troponin I
- B CK-MB
- C Myoglobin ✓
- D LDH-1
Correct answer: C. Myoglobin
Explanation
Myoglobin, a small cytosolic heme protein abundant in cardiac and skeletal muscle, leaks rapidly through damaged membranes and becomes detectable within 1 to 3 hours of symptom onset, peaking around 6 to 12 hours. Troponins begin to rise at 3 to 4 hours, CK-MB at 4 to 6 hours, and LDH much later. The limitation of myoglobin is its poor cardiac specificity, since skeletal muscle injury also raises it, so it serves only as an early rule-out marker.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.