At a glance

Also known as

TnI; TnT

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

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 other substances (CK–MB) that may be measured if a heart attack is suspected and the troponin test is not available. 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, indigestion, 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, have a higher risk of having a heart attack or other serious heart problems 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 (CK–MB if troponin test not available), in persons who have prolonged chest pain or pain that occurs at rest.

What does the test result mean?

Looking for reference ranges?

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.

Common Questions

What does heart attack mean?

Heart attack means that some of the muscle in your heart has died. A medical term for this is myocardial infarction. Most commonly, a heart attack starts with a kind of heavy pressure or pain in the chest, often extending into the neck or left arm. You may have trouble catching your breath or you may feel weak and break into a cold sweat.

A heart attack usually occurs because one of the blood vessels (called coronary arteries) that bring blood to your heart muscle is blocked. This happens when a blood clot forms in a blood vessel that is already partially blocked. The partial blockage, which happens gradually over many years, is usually caused by too much fat layered in the wall of the blood vessel (this is often called hardening of the arteries — the medical term for this is atherosclerosis).

If I have chest pain, does that mean I am having a heart attack?

Many other problems can cause chest pain, and it is not always possible to tell just from the type of chest pain whether or not you are having a heart attack. Many people have chest pain from straining the muscles in their chest, and chest pain can occur with some lung problems. Chest pain can be a warning sign of hardening of the arteries of the heart called coronary artery disease (CAD). Chest pain that occurs during exercise, hard work, or at times of stress, lasts for a few minutes and goes away with rest is called angina. If the pain lasts longer than just a few minutes, especially if it occurs when you are resting, seek immediate medical attention.

What are the other heart attack tests?

Troponin has replaced previous tests as the recommended test for diagnosing a heart attack. CK-MB may be used if troponin tests are not available.

What if I’m not sure I’m having a heart attack?

If you have prolonged chest pain, especially if it does not go away with rest — or if you have been told you have angina, and the drugs you were prescribed do not ease the pain, seek immediate medical attention.