Myocardial isonzyme of CK which is specific for myocardial infarction is-

Ref: R. Alagappan Manual for 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 dys- trophy, 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 days