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Heart Attack Tests - Troponins

What are troponins?

Troponins are proteins found in skeletal and heart muscle fibers that help muscles to contract. Cardiac troponin tests measure levels of troponin T and troponin I because these are found only in heart muscle. When a person has a heart attack, troponin is released into the blood three to six hours later. The cardiac troponin test is better for diagnosing a heart attack than the CK, CKMB, or myoglobin tests because troponins are not found in the blood of healthy people. Damage to other muscles does not affect levels of the cardiac troponins. Troponin levels rise three to six hours after heart attack symptoms begin and stay high for up to one to two weeks after a heart attack.

Who might have the test?

Cardiac troponin tests help diagnose or rule out heart attack. Troponin tests are used in patients who have chest pain or other heart attack symptoms to see if they have had a heart attack or other heart damage. If you are hospitalized because of heart attack symptoms, you will be tested two to three times during a 12- to 16-hour period.

What does the test entail?

A blood sample is taken from a vein in your arm. In some hospitals, a bedside or point-of-care test is available in which only a finger prick and a few drops of blood are necessary. The blood is placed on a strip and positive results are available almost immediately if troponin levels are elevated. It takes about 15 minutes to ensure a negative result. The test takes less than a minute.

What do the results mean?

Troponins are not usually found in the blood of healthy people, so even slight elevations indicate some damage to the heart—usually a heart attack. Because troponin levels remain high for up to two weeks, a positive test may not distinguish between an ongoing heart attack or one you had earlier. A CKMB test can help in this situation.

What are the limitations of this test?

Troponins may not be detectable in the blood for three to 12 hours after the onset of heart attack symptoms; therefore, this test is not useful in the very early diagnosis of a heart attack. Patients with kidney failure may have higher troponin levels. Patients treated with heparin, a blood thinning medication, may get a falsely high troponin level with some test methods.


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