How is it used?
Troponin tests are primarily ordered for people who have chest pain to see if they have had a
heart attack or other damage to their heart. Either a troponin I or a troponin T test can be performed; usually a laboratory will offer one test or the other. Troponins are sometimes ordered along with other
cardiac biomarkers, such as
CK–MB or
myoglobin. However, troponins are the preferred tests for a suspected heart attack because they are more specific for heart injury than other tests (which may become positive in skeletal muscle injury) and remain elevated for a longer period of time.
The troponin test is used to help diagnose a heart attack, to detect and evaluate mild to severe heart injury, and to distinguish chest pain that may be due to other causes. In patients who experience heart-related chest pain, discomfort, or other symptoms and do not seek medical attention for a day or more, the troponin test will still be positive if the symptoms are due to heart damage.
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When is it ordered?
The troponin test will usually be ordered when a patient with a suspected
heart attack first comes into the emergency room and then may be repeated at 6 and 12 hours later. It is sometimes ordered along with other tests such as
CK,
CK–MB, or
myoglobin. Typically, 2 or 3 troponin tests are done over a 12- to 16-hour period.
In patients with stable angina, a troponin test may be ordered if the patient’s symptoms get worse, occur when the patient is at rest, and/or no longer ease with treatment. These are all signs that the angina is becoming unstable, which increases the risk of a heart attack or other serious heart problem in the near future.
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What does the test result mean?
Normally, cardiac troponin levels are so low that they cannot be measured. Even slight elevations may indicate some degree of damage to the heart. When a patient has significantly elevated troponin concentrations, then it is likely that the patient has had a
heart attack or some other form of damage to the heart. When a patient with chest pain and/or known stable
angina has normal troponin values, then it is likely that their heart has not been injured.
Troponin values can remain high for 1–2 weeks after a heart attack. The test is not affected by damage to other muscles, so injections, accidents, and drugs that can damage muscle do not affect troponin levels. Troponin may rise following strenuous exercise, although in the absence of signs and symptoms of heart disease, it is usually of no medical significance.
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Is there anything else I should know?
Increased troponin concentrations should not be used by themselves to diagnose or rule out a
heart attack. A physical exam, clinical history, and
ECG are also important. Some people who have a heart attack will have normal troponin concentrations, and some people with increased troponin concentrations have no apparent heart injury. Troponin levels may also be elevated with
acute or
chronic conditions such as myocarditis (heart inflammation),
congestive heart failure, severe infections,
kidney disease, and certain chronic inflammatory conditions of muscles and skin.
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