At a Glance
Why Get Tested?
To determine if you have had a heart attack
When to Get Tested?
If you are having chest pain that may be a heart attack
Sample Required?
A blood sample drawn from a vein in the arm
Test Preparation Needed?
None
The Test Sample
What is being tested?
This test measures the level of troponin in your blood. Troponin is a protein found in muscle that helps it contract. There are two forms that can be measured — troponin I (TnI) and troponin T (TnT) — found in the heart and in other muscles. The tests for these forms of troponin measure only the type found in heart muscle. When a person has a heart attack, troponin is released into the blood. Troponin levels remain high longer than some other substances (such as CK, CK–MB, and myoglobin) that may also be measured if a heart attack is suspected. This becomes important if a person waits for more than a day before going to the doctor after having had chest pain.
How is the sample collected for testing?
A blood sample is taken by needle from a vein in the arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
The Test
How is it used?
Troponin levels are used in persons who have chest pain to see if they have had a heart attack or other heart damage. Chest pain can be due to heart problems, indigestgion, strain on chest muscles or other causes. If the heart does not get enough oxygen, it causes chest pain during exercise. This is usually due to a partial blockage of the blood vessels caused by a gradual build up of fat (atherosclerosis, or hardening of the arteries). This type of pain which is felt during exercise and which stops when a person rests is called angina.
Sometimes a small blood clot forms in a blood vessel, causing chest pain while a person is at rest, or which continues after exercise stops. If the blood clot clears, the chest pain will stop; this condition is called 'unstable angina'. In a heart attack, the blood clot remains, causing heart muscle cells to die and release their contents, including troponin, myoglobin and CK. In unstable angina, the heart cells may also release troponin. Studies have shown that people who have unstable angina and high troponin, but normal CK, CK–MB and myoglobin, have a higher risk of having a heart attack or other serious heart problem in the next few months. Many doctors now check troponin in persons with unstable angina to identify those who may benefit from such treatments as angioplasty (using a balloon to open a blocked heart blood vessel) or heart bypass surgery.
When is it requested?
Troponin tests are usually requested, sometimes with other heart tests such as CK, CK–MB, or myoglobin, in persons who have prolonged chest pain or pain that occurs at rest.
What does the test result mean?
Normally, troponin levels are very low; even a slight rise indicates some damage to the heart (unstable angina or a heart attack). Troponin will remain high for 1–2 weeks after a heart attack. Troponin is not generally affected by damage to other muscles, so that muscle injections, accidents, strenuous exercise and drugs that can damage muscle do not affect troponin levels.
Is there anything else I should know?
Troponin levels may be slightly elevated in persons with kidney failure. Sometimes, if a person is getting a drug called heparin (often used to treat suspected unstable angina or heart attack), a falsely high troponin can occur with some test methods. Two forms of troponin can be measured (troponin T and troponin I) and laboratories will select one or the other.
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