Among the following biochemical markers of acute myocardial infarction, which one appears in blood EARLIEST after coronary occlusion?

• A Cardiac troponin I
• B CK-MB mass
• C Myoglobin ✓
• D LDH-1

Explanation

Myoglobin, a small cytoplasmic heme protein of about 17 kDa, leaks rapidly through damaged sarcolemma and becomes detectable in serum within 1 to 3 hours of symptom onset, earlier than CK-MB at 4 to 6 hours or troponin at 3 to 6 hours. Its usefulness is limited by poor cardiac specificity because skeletal muscle injury and renal failure also raise it, and by rapid renal clearance within about 24 hours. LDH-1 rises last, peaking around 3 to 4 days.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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