Cardiac biomarkers: Troponin & Myoglobin - A student nurses guide Cardiac biomarkers are essential in diagnosing acute coronary syndrome (ACS) and myocardial injury. Troponin What is it? - A highly specific protein found in cardiac muscle cells - Released when myocardial injury occurs such as myocardial infarction - Gold standard for diagnosing acute coronary syndrome Myoglobin What is it? - A non-specific muscle protein found in cardiac & skeletal muscle - Released into circulation rapidly after muscle injury Pro Tips: - Troponin is the most reliable marker for MI diagnosis - Myoglobin rises quickly, but is less useful due to low specificity - Results should always be correlated with ECG changes, symptoms, and patient history - Serial testing over time gives a better picture of ongoing myocardial damage