Question

The client is admitted two weeks after the onset of chest pain. Which laboratory test is the most indicative for a myocardial infarction? A. Creatine kinase (CK-MB) B. Troponin level C. Lactic acid dehydrogenase (LDH) D. Blood urea nitrogen (BUN)

Short answer

Answer: B. Troponin level

Step-by-step solution

Understand the terminology

A myocardial infarction, also known as a heart attack, occurs when blood flow to a part of the heart is blocked, usually by a blood clot. This can damage or destroy part of the heart muscle. Laboratory tests are essential for the diagnosis of myocardial infarction. The exercise provides four options for laboratory tests indicating a myocardial infarction.

Characteristics of each laboratory marker

Each marker has a different time course and specificity for myocardial infarction: A. Creatine kinase (CK-MB): CK-MB is an enzyme present in the heart muscle. Its levels increase after a heart attack and peak within 24 hours, but they return to normal within about 2-3 days. B. Troponin level: Troponins are proteins found in heart muscle that help regulate muscle contractions. Troponin levels rise about 4-6 hours after a heart attack starts, peaking within 12-48 hours, and can remain elevated for up to 14 days. C. Lactic acid dehydrogenase (LDH): LDH is an enzyme that rises about 6-12 hours after a heart attack, peaks within 2-3 days, and normalizes in 8-14 days. D. Blood urea nitrogen (BUN): BUN is a measure of kidney function and does not have a specific time course for myocardial infarction. It is not a reliable test for detecting heart attacks.

Identify the most appropriate test

You are looking for the most indicative test for myocardial infarction two weeks after the onset of chest pain. Based on the information about the time course of each laboratory marker, the most accurate test for this scenario is: B. Troponin level