first ctni and later ctnt were originally used as markers for cardiac cell death. both proteins are now widely used to diagnose acute myocardial infarction (ami), unstable angina, post-surgery myocardium trauma and some other diseases related with cardiac muscle injury. both markers can be detected in patient’s blood 3–6 hours after onset of the chest pain, reaching peak level within 16–30 hours. 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.