Myocardial isonzyme of CK which is specific for myocardial infarction is

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 dys- trophy, Myopathies 2. Electrical cardioversion 3. Skeletal muscle damage – trauma, convulsions, immobilisation 4. Hypothyroidism 5. Stroke 6. Surgery b. AST: Starts rising on the 1st day, peaks in 2–3 days (3 fold rise) and disappears by 3rd day. c. LDH1: Starts 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 start to rise within 3-4 hours after myocardial infarction and remain raised for 4-10 days