Medical Surgical Labs Cardiac #3

Question

Which are proteins found in skeletal and myocardial muscles that are released into the bloodstream when blockage of blood flow occurs to the heart muscle?

Answers

  1. Myoglobin
    • Rationale:

      This answer is not correct because myoglobin is a protein found in skeletal and myocardial muscle that provides oxygen. It is not cardiac specific, therefore it is not used to diagnose heart attacks.

  2. Creatine kinase
    • Rationale:

      This answer is not correct because creatine kinase is an enzyme that shows if there is any tissue damage from trauma. This enzyme is found in the brain and muscle tissues.

  3. Lactate dehydrogenase
    • Rationale:

      This answer is not correct because LDH is an enzyme found in cells. It is only used to differentiate acute from subacute heart attacks when troponin levels are found to be elevated.

  4. Troponin
    • Rationale:

      This answer is correct because troponins are proteins released into the bloodstream during an infarction. Troponin levels may elevate 3 hours after the muscle injury and may remain elevated up to 14 days. Troponin levels are tested serially, 12 hours after initial testing, and then daily testing for 3 to 5 days.

Overview

Blockage of blood flow to the heart muscle is called a myocardial infarction (heart attack). Increased amount of troponin releases when damage to the heart muscle occurs.

Explanation

Learning Outcomes

Troponins are proteins released into the bloodstream during an infarction. Blockage of blood flow to the heart muscle is called a myocardial infarction (heart attack). Increased amount of troponin releases when damage to the heart muscle occurs. Troponin levels may elevate 3 hours after the muscle injury and may remain elevated up to 14 days. Troponin levels are tested serially, 12 hours after initial testing and then daily testing for 3 to 5 days. Myoglobin is a protein found in skeletal and myocardial muscle that provides oxygen. Since it is not cardiac specific, it is not used to diagnose heart attacks, but is considered a cardiac marker to observe. Creatine kinase is another cardiac marker. It is an enzyme that shows if there is any muscle or tissue damage from trauma. LDH is only used to differentiate the severity of the heart attack when troponin levels are found to be elevated.

Test Taking Tip

Know the cardiac markers and how they function when there is muscle damage.

Video Rationale