A patient is brought to the emergency department with complaints of chest pain radiating to the shoulder and shortness of breath. Which of the following lab tests is most important to obtain and evaluate?

Troponin-I

Explanation

• Troponin-I is highly specific for cardiac muscle necrosis and is the most accurate lab test for myocardial infarctions. It rises in 3-4 hours and can be detected for up to 10-14 days. Of note, an electrocardiogram (EKG) is also one of the first tests ordered for patients with a suspected myocardial infarction (MI).

• Incorrect: CK-MB is used to test for cardiac damage but is also present in small amounts in skeletal muscle and it peaks in 12-24 hours, so it is not the best test to use.

• Incorrect: The other tests are less specific than Troponin-I. Myoglobin is a protein that is present in both heart and skeletal muscles. Lactate dehydrogenase (LDH) is an enzyme found in almost all cells of the body, so this makes it the least specific of all the tests.

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