Troponin Test

What is a troponin test?

A troponin test looks for the protein troponin (there are two forms related to your heart, troponin I and troponin T) in your blood. Normally, troponin stays inside your heart muscle’s cells, but damage to those cells — like the kind of damage from a heart attack — causes troponin to leak into your blood. Higher levels of troponin in your blood also mean more heart damage, which can help healthcare providers determine the severity of a heart attack.

Newer versions of this test are much more sensitive and can pick up far smaller amounts of this protein in your blood than before. That can speed up the process of diagnosing a heart attack. This test is also useful when other tests are inconclusive or when you have vague symptoms. This test is also known as a cardiac troponin test, or uses the abbreviations cTn, cTnI or cTnT, depending on the specific type of test. Some versions of this test can only detect one type of troponin, while others can detect both.

What is troponin?

Troponin is a protein, a complex chemical molecule, found in certain types of muscle in your body. Under normal circumstances, it exists inside muscle cells and only freely circulates in your bloodstream in tiny amounts. However, damage to certain types of muscle cells can cause more troponin to escape into your blood.

There are two types of troponin that are more detectable after heart muscle damage, which use the letters I and T to tell them apart.

• Troponin I (cTnI). This kind of troponin is unique to heart muscle.
• Troponin T (cTnT). Troponin T does exist in other types of muscle, but the amounts are very limited. The Troponin T in your heart muscle also has a slightly different structure, which doesn’t occur anywhere else in your body.

Troponin levels usually increase sharply within three to 12 hours after a heart attack and peak about 24 hours after the heart attack. They will also remain high for several days.

Why would I need this test?

The most common use of troponin tests is to confirm or rule out a heart attack. However, any kind of damage to heart muscle can potentially cause the release of this chemical into your bloodstream. Other conditions that can cause your troponin levels to increase include:

• Chronic kidney disease.
• Pulmonary embolism (a blood clot in your lungs).
• Congestive heart failure.
• Heart surgery.
• Heart valve diseases.
• Irregular heart rhythms (arrhythmias).
• Sepsis.
• Exercising too much or too strenuously.
• Extreme emotional strain, such as grief or stress.

When and where is this test performed?

This test sees most of its use in hospital emergency rooms when medical professionals suspect a recent heart attack. However, if you're already a patient in the hospital and doctors need to check for heart damage for any reason, this test might also provide useful information.

How does a troponin test work?

This test involves taking a sample of your blood, analyzing it and determining if there's any troponin in the sample. If the troponin level is high enough, it's a clear indicator of heart damage. This test, combined with other diagnostic tests and methods, is a key tool to diagnose a heart attack.

Repeating this test is common because comparing your troponin levels over time can help providers determine the extent of the heart damage and the likely prognosis for your case. Troponin is also useful even days after a heart attack because troponin I levels will remain high for at least five to seven days after a heart attack. Troponin T levels last even longer and will remain high for up to three weeks after a heart attack.

Newer, high-sensitivity tests can often detect even the tiny amounts of troponin in your blood that happen normally. In these cases, providers will repeat the test. If they see an increase in the troponin level on the repeat test, that’s an indication of heart muscle damage.

Can I prepare for it, and what should I expect?

For the most part, heart attacks are unpredictable and that means you can’t prepare for this test.

Important: If you need to undergo a troponin test, tell your doctor if you take Vitamin B7 (also known as biotin) and what dose you take. This vitamin can interfere with the results, and your doctor will need to know about this beforehand. Depending on the dosage you take, it may be several hours before the biotin can no longer affect your results.

Under most circumstances, healthcare providers will treat a heart attack as a presumed positive using medication or less-invasive methods before getting the results of a troponin test. In many cases, they do this based on your symptoms or other test results because that saves precious time when minutes can make all the difference. If the results don’t show elevated troponin levels after 12 hours, your provider(s) can adjust how they care for you accordingly.

What should I expect during the test?

This test involves a blood draw for a sample. A phlebotomist or other trained professional will insert an intravenous (IV) needle into a vein (usually a vein in your arm) and fill up one or more test tubes with blood. If you already have an IV line inserted into a vein, a provider may use that line to collect the blood sample.

When should I expect to know the results?

Test results usually come back in one to two hours. Once they do, your healthcare provider will talk to you about your results and what they mean. Some people may need follow-up testing and additional medical care because of continuing symptoms or concerns, while others may be well enough to go home. Your provider can also tell you more about what to expect going forward, as what happens next can change from case to case.

Are there side effects or potential complications?

In most cases, there are minimal or no side effects from this test. In most cases, there is only a slight pinch or poke when inserting the needle to take the blood sample (unless an existing IV line is available to take the sample). You may develop a small bruise, especially if you bruise easily, but these usually go away within a few or several days.

What type of results will I get and what do the results mean?

If your results fall into the “reference range” for this test, then that means your result was within the expected range for a healthy individual. However, the reference range may vary slightly depending on where you receive your test and the type of test they use.

Troponin test result ranges

In healthy adults, the reference range (expected level) of troponin is very low or undetectable. When troponin levels are higher than the reference range that means damaged heart muscle cells are leaking troponin into your blood.

The reference ranges for the troponin test, according to the American Board of Internal Medicine, are measured in nanograms per milliliter (ng/mL). They are:

• Troponin I: 0 - 0.04 ng/mL.
• Troponin T: 0 - 0.01 ng/mL.

Note: It takes 1 billion nanograms to make 1 gram, and 1 gram is about the weight of a small paper clip. A liter is about 1/4 gallon, and it takes 1,000 milliliters to make a liter. Some facilities will use micrograms (mcg or μg, meaning one-millionth of a gram) or picograms (pg, meaning one-trillionth of a gram). If you have any questions or concerns about the results, including the units listed for the results, your healthcare provider can explain them so you can better understand what they mean.

The medical standard for elevated troponin levels is for them to be higher than 99% of the expected value in a healthy adult (there’s also a small margin that accounts for how precise that specific test is). If your results are higher than 99% of the expected value (and the margin for precision), that indicates heart muscle damage. Depending on your symptoms, other test results, and medical history, a healthcare provider can confirm or rule out a heart attack.

Some of the other conditions that can cause high troponin levels include the following:

• Heart surgery.
• Infections or inflammation in your heart.
• Cardioversion (this is the use of an electric shock to make an irregular heart rhythm return to normal).

When should I call my doctor?

Because this test almost always happens in a hospital setting, it's unlikely that you'll need to call your doctor. However, you can request sharing of records and results from your troponin test with any healthcare providers you see regularly, especially if you are receiving care while traveling or at a facility that doesn't regularly share information with your usual provider(s).

A note from Cleveland Clinic

The troponin test plays a vital role in the diagnosis of a heart attack. While this test has been around for decades, the technology and methods behind the test have advanced significantly. That means that the test is far more accurate, precise, and faster than in years past. All those improvements mean that this test is one of the best ways to ensure that you get the right care for a heart attack.