Troponin (I or T)

Troponin tests are used, together with an electrocardiogram (ECG), in people with chest pain to see if they have had a heart attack, have unstable angina or have a problem outside the heart. In a heart attack, a blood clot stops the normal flow of blood and oxygen to the muscle. Without oxygen, the heart muscle cells die and release troponin into the bloodstream. The more extensive the damage is, the greater the release and the higher the blood concentrations become. Concentrations can increase within two or three hours and may remain high for 10 to 14 days. The rise or fall in troponin level is important to differentiate any acute cardiac events such as heart attack from chronic elevations not due to a heart attack.

Troponin tests are usually requested in persons who have prolonged chest pain or pain that occurs at rest.

Normally, troponin levels are very low; even a slight rise indicates some damage to the heart (unstable angina or a heart attack). When a patient has a large increase in troponin concentration, then it is highly likely that they have had a heart attack or some other form of heart damage. If a patient with chest pain and known stable angina has a normal and stable troponin result, it is likely that their heart has not been damaged.

Increased troponin concentrations should not be used by themselves to diagnose or rule out a heart attack. A physical examination, clinical history and electrocardiogram (ECG) or imaging investigations are also essential. The internationally agreed definition of heart attack requires evidence of a significant increase in troponin concentration with time, together with evidence of a sudden reduction of heart muscle blood supply (ischaemia) for example the characteristic symptoms of the acute coronary syndrome (ACS), new ECG changes or new imaging changes.

Without evidence of ischaemia, possible causes of rising troponin values include myocarditis (inflammation of the heart muscle), acute heart failure, an arrhythmia (abnormal heart rhythm) or pulmonary embolism (blood clot lodged in the lung). Elevated but unchanging values may be seen in chronic heart failure, high blood pressure (hypertension), severe infections, kidney disease and some chronic inflammatory conditions of muscle.

About Reference Intervals

The test is not generally affected by damage to muscles other than the heart, so injections into muscle and accidents or drugs that damage muscle do not normally affect troponin concentrations.
 

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).

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.

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.

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.