Cardiac markers in Myocardial infarction (MI)

Let's learn about the biochemistry of cardiac markers used in MI.

1. MYOCARDIAL INFARCTION

2. LEARNING OBJECTIVE To describe the different cardiac markers used in the diagnosis of myocardial infarction.

3. CARDIAC MARKERS Enzymes or proteins Normally absent or present in low amount in plasma Released in blood in large quantities due to membrane damage Rate of release depends on Molecular weight Intracellular location Local blood and lymph flow

4. Cardiac markers used in diagnosis of myocardial infarction are : Enzymes Proteins Creatine kinase (CK-MB) Cardiac troponins (cTnI, cTnT) Lactate dehydrogenase Myoglobin Aspartate aminotransferase Ischemia modified albumin Alanine aminotransferase Fatty acid binding protein Glycogen phosphorylase

5. Cardiac markers Myoglobin Creatine kinase (CK-MB) Cardiac troponins (cTnI, cTnT) Lactate dehydrogenase (LDH) Molecular weight 17 kDa Early marker 40 kDa cTnI: 21 kDa cTnT: 37 kDa 134 kDa Sources Skeletal muscle C ardiac muscle Smooth muscle Cardiac muscle Skeletal muscle Cardiac muscle (Cardiac specific) Heart, RBC Kidney, Brain Skeletal muscle Liver Intracellular location Cytoplasm Myofibril Cytoplasm Mitochondria Myofibrils96% Cytoplasm-4% Cytoplasm Diagnostic window Onset:1-4 hour Peak: 6-7 hour Onset:4-6 hour Peak:18-24 h Onset:2-6 hour Peak:18-24 h Onset:10-12 h Peak: 2 days Back to normal Within 1 day 3-5 days cTnI: 5-10 days cTnT:5-14 days 7-10 days

6. Cardiac markers in myocardial infarction

7. Lactate dehydrogenase (LDH) isoenzymes LDH isoenzyme “switch”(usually within12-24 hours)

8. REFERENCES Textbook of BIOCHEMISTRY WITH CLINICAL CORRELATIONS; 7 th EDITION; THOMAS M. DEVLIN; (Page no.419-420) MEDICAL BIOCHEMISTRY; BAYNES DOMINICZAK; 3 rd EDITION; (Page no.68-69) Tietz Textbook of CLINICAL CHEMISTRY AND MOLECULAR DIAGNOSTICS; 1 ST EDITION; (Page no.406-410) Robbins & Cotran Pathologic Basis Of Disease; Volume 2; 9 th Edition; Page no.547

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