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 can be performed; usually a laboratory will offer one test or the other. The troponin test may be ordered by itself or along with other cardiac biomarkers, tests for substances such as CK, CK–MB, and myoglobin. Troponin I and troponin T tests have begun to replace CK and CK-MB tests because they are more specific for heart injury (versus skeletal muscle injury) and are elevated for a longer period of time, but many doctors still prefer to have the additional information they get by ordering more than one cardiac biomarker.

The troponin test will usually be ordered when a patient first comes into the emergency room and then may be ordered again at 6 and 12 hours. The troponin test is used to help diagnose a heart attack, to detect and evaluate mild to severe heart injury, and to separate it from chest pain that may be due to other causes. In patients who have delayed getting treatment and have been having heart-related chest pain, discomfort, or other symptoms such as sweating, radiating pain in the arms, shoulders, jaw, neck, nausea, and/or lightheadedness for more than a day, the troponin test is the test of choice. This is because it will still be elevated in the blood if the symptoms were/are due to heart damage.

Troponin tests are usually ordered, often along with other heart tests such as CK, CK–MB, or myoglobin, when a patient has prolonged chest pain or other symptoms that could be related to heart injury. Typically, troponin is done 2 or 3 times during a 12- to 16-hour period. In patients with stable angina (predictable episodes of chest pain related to an inadequate flow of blood to the heart that resolve with rest and/or medication), the troponin test may be ordered when the patient’s symptoms escalate, occur when the patient is at rest, and/or no longer ease with treatment, signs that the angina is becoming unstable, putting the patient at a much higher risk of having a heart attack or other serious heart problem in the near future.

Normally, troponin levels are very low; even slight elevations can indicate some degree of damage to the heart. When the patient has significantly elevated troponin concentrations and other clinical signs, such as an abnormal electrocardiogram (ECG), then it is likely the patient has had a heart attack. If CK, CK-MB, and myoglobin concentrations are normal but troponin levels are increased, then it is likely that either a lesser degree of heart injury is present or that the injury took place more than 24 hours in the past. If the first troponin performed is normal but subsequent (6 hour and 12 hour samples) troponin tests are increased, then the heart injury likely occurred within a couple of hours prior to the first test and had not had time to increase. When a CK test is elevated but a CK-MB (which is more heart-specific than CK) and troponin test are normal, then it is likely that whatever symptoms are present are due to another cause, such as skeletal muscle injury. When a patient with chest pain and/or known stable angina has normal troponin, CK, and CK-MB concentrations, then it is likely that their heart has not been injured.

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.

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 are having 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, dermatomyositis, and polymyositis.