Ref: R Alagappan - Manual of Practical Medicine 4th Edition.pg no:184 Cardiac Enzymes a. CPK-MB: This cardiac isoenzyme stas rising within 4-6 hrs after development of acute MI, peaks during the 2nd day (4 fold rise) and disappears in 2-3 days. Other causes of total CK elevation: 1. Skeletal diseases - Polymyositis, Muscle dystrophy, Myopathies 2. Electrical cardioversion 3. Skeletal muscle damage - trauma, convulsions, immobilisation 4. Hypothyroidism 5. Stroke 6. Surgery b. AST: Stas rising on the 1st day, peaks in 2-3 days (3 fold rise) and disappears by 3rd day. c. LDH1: Stas rising by second day, peaks around 3- 4 days ( 3 fold rise) and disappears in 10 days. d. Troponin T: Cardiac troponin T is a regulatory contractile protein not normally found in blood. Its detection in the circulation has been shown to be a sensitive and specific marker for myocardial cell damage. Troponin T and I reach a reliable diagnostic level in plasma by 12-16 hrs, maximal activity by 24-32 hrs, returns to normal in 10-12 days. Troponin I : 0-0.4 ng/ml Troponin T: 0-0.1 ng/ml Cardiac troponins are detected in the serum by using monoclonal antibodies. These antibodies have negligible cross reactivity to skeletal muscle. Cardiac troponins I and T sta to rise within 3-4 hours after myocardial infarction and remain raised for 4-10 daysOther causes of elevated cardiac troponins: Cardiac causes: * Cardiac contusion/surgery * Myocarditis * Cardiomyopathy * Hea failure * Cardioversion * Percutaneous coronary intervention * Cardiac amyloidosis * Radiofrequency ablation * Supraventricular tachycardia * Post-cardiac transplantation Non-cardiac causes: * Primary pulmonary hypeension * Pulmonary embolism * Cerebrovascular stroke * High dose chemotherapy * Sepsis and septic shock * Renal failure * Critically ill patients * Scorpion envenomation * Ultra-endurance exercise (marathon) e. Myoglobin It is increased within 2 hrs of onset of symptoms and remains increased for at least 7-12 hrs. Normal level is 20-100 mg/L.