Which one of the following markers begin to rise about 6 hours after Myocardial Infarction and peaks in 18 ho… - ESIC Nursing Officer-7July 2024

ESIC Nursing Officer-7July 2024

Medical Surgical Nursing

Easy

Appeared in: ESIC Nursing Officer-7July 2024

Explanation

CK-MB (Creatine Kinase-MB) is an isoenzyme of creatine kinase found primarily in heart muscle.
Following a myocardial infarction (MI), damaged heart muscle cells release CK-MB into the bloodstream.
According to clinical data, CK-MB levels begin to rise within 3-6 hours after the onset of MI.
The concentration of CK-MB peaks in the blood at approximately 18-24 hours.
This timeline directly corresponds to the rise (6 hours) and peak (18 hours) specified in the question.

Option B: Cardiac Troponin T (cTnT) remains elevated in the blood for a much longer period, up to 10-14 days, and its peak is generally observed between 18-24 hours but can be later. The key differentiator is its long duration compared to CK-MB.
Option C: Myoglobin is the earliest marker to appear after an MI, rising within 1-4 hours and peaking at 6-7 hours. This is too early to match the 18-hour peak described in the question.
Option D: Similar to cTnT, Cardiac Troponin I (cTnI) has a prolonged elevation, staying in the blood for 7-10 days. While its peak can be around 14-24 hours, its primary characteristic is long-term elevation, not a specific peak at 18 hours followed by a quick decline.

Visual 1: Graph - A line graph comparing the serum concentrations of Myoglobin, CK-MB, and Troponins over time (0-14 days) after a myocardial infarction. This visual clearly illustrates the different onset, peak, and duration for each marker, making the concept easy to remember.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Timeline of Cardiac Markers in Myocardial Infarction as background academic context rather than a clinical decision trigger.
Understanding the timelines of cardiac markers is crucial for nurses in accurately interpreting lab results and assessing the stage of a myocardial infarction.
Serial sampling is a key nursing intervention. Blood is typically drawn on admission, and then at 3-6 hour intervals to track the rise and fall of these markers, confirming the diagnosis and assessing the extent of damage.
CK-MB is particularly useful for detecting reinfarction (a second heart attack) shortly after the first one. Because it returns to normal within 2-3 days, a new rise in CK-MB indicates a new event, whereas troponin levels would still be elevated from the initial MI.

How to Approach the Question

First, identify the core of the question. The question is asking for a specific cardiac marker based on its time of rise (around 6 hours) and peak (around 18 hours) after an MI.
This is a factual recall question. You need to access your knowledge of the characteristic timelines for the main cardiac biomarkers.
Mentally review or sketch out the timelines for Myoglobin, CK-MB, and Troponins.
Compare the timeline given in the question (rise ~6h, peak ~18h) with the known timelines of each marker in the options.
Myoglobin: Rises and peaks too early.
Troponins: Rise time is similar, but they peak later and stay elevated for much longer.

Concept Tested & Keywords

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