In a patient with myocardial infarction, serum creatine kinase enzyme (CK) increases within hours.?

Appeared in: MP CHO - 2022

Explanation

Following a myocardial infarction (MI), the creatine kinase-MB (CK-MB) isoenzyme is released from damaged cardiac muscle cells.
Serum levels of CK-MB begin to rise within 3 to 6 hours after the onset of chest pain or myocardial injury.
This makes CK-MB an important early biomarker for the diagnosis of acute MI, although cardiac troponins are more specific and remain elevated for longer.
The peak level of CK-MB is typically reached around 18-24 hours, and it returns to baseline within 2-3 days.

Option A: This timeframe (2-4 days) represents the period when CK-MB levels typically return to normal after an MI, not the initial increase.
Option C: This timeframe (18-24 hours) corresponds to the peak concentration of CK-MB in the blood, not the onset of its rise.
Option D: This duration (3-6 days) is more aligned with the elevation period of cardiac troponins, which stay in the bloodstream longer than CK-MB.

Clinical Relevance

Nursing practice connection: Use the key finding related to Timeline of cardiac markers after myocardial infarction to guide bedside assessment, documentation, and the next nursing action.
Nurses play a critical role in ensuring timely collection of blood samples for cardiac marker analysis in patients with suspected MI. This is essential for prompt diagnosis and treatment.
Understanding the timeline of cardiac markers helps the nurse anticipate orders for serial testing (e.g., every 6-8 hours) to observe the characteristic rise and fall pattern, which confirms the diagnosis.
Nurses should avoid administering intramuscular (IM) injections to patients with suspected MI, as the resulting skeletal muscle injury can falsely elevate total CK levels, complicating the interpretation of CK-MB results.

How to Approach the Question

First, identify the core of the question, which is about the timing of a specific cardiac marker (Creatine Kinase, CK) after a myocardial infarction (MI).
Recall the different cardiac biomarkers (CK-MB, Troponin, Myoglobin) and their characteristic timelines.
Focus specifically on the 'onset' or 'initial rise' of CK, as requested by the question.
Compare the given timeframes in the options with your knowledge of the CK-MB timeline.
Select the option (3-6 hours) that matches the known initial rise of CK-MB.
Mentally differentiate this from the peak time (18-24 hours) and normalization time (2-3 days) to confirm the other options are incorrect distractors.

Concept Tested & Keywords

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E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 259-261

E6 PATHOLOGY QUICK REVIEWBased on Harsh Mohan Textbook of PATHOLOGY p. 196-198

Practise the full MP CHO - 2022

Attempt every question from this paper in a timed mock, then review the full solution for each one.