Cardiac troponin (cTn), cardiac troponin I (cTnI), cardiac troponin T (cTnT)
This test measures the amount of the protein troponin in your blood.
Troponin is found in cells in your heart muscle. When these cells are injured – most often because the heart isn't getting enough oxygen and nutrients – they can release troponin and other substances into the blood.
Measuring your levels of troponin often can quickly tell your doctor whether you are having a heart attack. During a heart attack, an artery that feeds your heart muscle with blood becomes blocked.
You might have this test if your doctor suspects that you are having a heart attack. Symptoms of a heart attack often include:
Pain or discomfort in the chest that may feel like a squeezing sensation or a sense of fullness
Pain in other areas, such as the neck, back, arm, or jaw
Shortness of breath
Lightheadedness or dizziness
Nausea or vomiting
Your doctor may also order other tests to diagnose a heart attack and learn more about how it's affecting the heart. These tests often include:
ECG to measure the heart's electrical activity
Blood tests to measure creatine kinase MB, a substance found in heart muscle and other tissues
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Results are given in nanograms per milliliter (ng/mL). The normal range for troponin is between 0 and 0.4 ng/mL.
Other types of heart injury may cause a rise in troponin levels. These include:
Damage to the heart from anthracycline drugs
Conditions in other parts of your body may cause troponin levels to rise. These include:
Pulmonary embolism, or a blood clot in your lungs
Chronic kidney disease
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Having this test too soon after a heart attack may give a false-negative. Cardiac troponin takes a few hours to rise after heart-cell death begins. Your health care provider may need to measure it several times over a few hours after the symptoms start.
You don't need to prepare for this test. But be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.