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: Troponin level

Step-by-step solution

Understand the Options

We have four given options, and we need to understand what each of these tests does and their role in diagnosing myocardial infarction. A. Creatine kinase (CK-MB) - This is a cardiac enzyme that is usually elevated when there is muscle damage, including damage to the heart muscle. It starts to rise 3-6 hours after the onset of chest pain and peaks at 12-24 hours. It returns to normal after 48-72 hours. B. Troponin level - Troponin is a protein complex found in heart and skeletal muscles. When there is damage to the heart muscle, troponin will be released into the bloodstream. It starts to rise 2-6 hours after the onset of chest pain and can remain elevated for up to 14 days. C. Lactic acid dehydrogenase (LDH) - This enzyme is found in various body tissues, including the heart and liver. It may be elevated after a myocardial infarction, but it is not specific for heart damage. D. Blood urea nitrogen (BUN) - This is a test that measures the amount of urea nitrogen in the blood. It is mainly used to diagnose kidney function and is not directly related to myocardial infarction.

Analyzing the Best Option for the Given Situation

The client is admitted two weeks after the onset of chest pain. So, we are looking for a laboratory test that can detect myocardial infarction within this timeframe. A. CK-MB - Its peak is too early (12-24 hours) and returns to normal after 72 hours. This makes it less useful for our case. B. Troponin level - It can remain elevated for up to 14 days, which fits our situation of the client being admitted two weeks after the onset of chest pain. C. LDH - It is not specific for heart damage, making it less reliable for diagnosing myocardial infarction. D. BUN - It is not directly related to myocardial infarction and focuses on kidney function instead.

Select the Most Indicative Test

Based on the analysis in Step 2, the most indicative laboratory test for myocardial infarction for a client admitted two weeks after the onset of chest pain is: B. Troponin level