Measurements of cardiac-specific troponins I and T are extensively used as diagnostic and prognostic indicators in the management of myocarditis, myocardial infarction and acute coronary syndrome.

[3] Blood troponin levels may be used as a diagnostic marker for stroke or other myocardial injury that is ongoing, although the sensitivity of this measurement is low.

[8] In both cardiac and skeletal muscles, muscular force production is controlled primarily by changes in intracellular calcium concentration.

[citation needed] Troponin is a component of thin filaments (along with actin and tropomyosin), and is the protein complex to which calcium binds to trigger the production of muscular force.

Under resting intracellular levels of calcium, tropomyosin covers the active actin sites to which myosin (a molecular motor organized in muscle thick filaments) binds in order to generate force.

[14] cTnI-TnC complex formation plays an important positive role in improving the stability of cTnI molecule.

[citation needed] Subtypes of troponin (cardiac I and T) are sensitive and specific indicators of heart muscle damage (myocardium).

They are measured in the blood to differentiate between unstable angina and myocardial infarction (heart attack) in people with chest pain or acute coronary syndrome.

A person who recently had a myocardial infarction has areas of damaged heart muscle and elevated cardiac troponin levels in the blood.

[15] This can also occur in people with coronary vasospasm, a type of myocardial infarction involving severe constriction of the cardiac blood vessels.

[17] Other conditions that directly or indirectly lead to heart muscle damage and death can also increase troponin levels, such as kidney failure.

[citation needed] Coronary artery stent placement can also cause immediate post-procedure elevated serum troponin levels.

[citation needed] Heart injury with increased troponins also occurs in cardiac contusion, defibrillation and internal or external cardioversion.

Troponins are commonly increased in several procedures such as cardiac surgery and heart transplantation, closure of atrial septal defects, percutaneous coronary intervention, or radiofrequency ablation.

[25] Strenuous endurance exercise such as marathons or triathlons can lead to increased troponin levels in up to one-third of subjects, but it is not linked to adverse health effects in these competitors.

Both proteins are now widely used to diagnose acute myocardial infarction (AMI), unstable angina, post-surgery myocardium trauma and some other related diseases with cardiac muscle injury.

Elevated concentration of cTnI and cTnT in blood samples can be detected even 5–8 days after onset of the symptoms, making both proteins useful also for the late diagnosis of AMI.