Prelim LAB Lesson 3 Liver Enzymes.pdf

SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE CLINICAL CHEMISTRY 2 MLS 418 [LAB]: ENZYMES OF CLINICAL SIGNIFICANCE: AMINOTRANSFERASES  ✓ State the clinical significance of the aminotransferases....

SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE CLINICAL CHEMISTRY 2 MLS 418 [LAB]: ENZYMES OF CLINICAL SIGNIFICANCE: AMINOTRANSFERASES  ✓ State the clinical significance of the aminotransferases. ✓ Describe the principles involved in the methods of enzyme LEARNING determination. OBJECTIVES ✓ Perform procedures to determine enzymatic activities. By the end of the lesson, the ✓ Correlate results with various students are expected to: physiologic and pathologic conditions. SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE CLINICAL CHEMISTRY 2  SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE TOPIC CLINICAL CHEMISTRY 2 OUTLINE We will learn the following: ▪ Aspartate & Alanine Aminotransferase ▪ Reactions Catalyzed ▪ Isoenzymes ▪ Methods of Determination ▪ Reference Values ▪ Clinical Significance ▪ Analytic Variables SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE CLINICAL CHEMISTRY 2 ASPARTATE AMINOTRANSFERASE NOMENCLATURE & FUNCTION ASPARTATE AMINOTRANSFERASE (AST) ▪ E.C. 2.6.1.1 ▪ L-Aspartate 2-Oxaloglutarate Aminotransferase ▪ Formerly: Serum Glutamic Oxaloacetic Transaminase (SGOT) ▪ Involved in the transfer of an amino group between aspartate and α- keto acids. ▪ Coenzyme: Pyridoxal phosphate (Vitamin B6) SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Bishop, M. L., Fody, E. P., & Schoeff, L. E. (2018). Clinical chemistry: Principles, procedures, correlations (Enhanced 8th ed). Jones & Bartlett. CLINICAL CHEMISTRY 2 SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Krebs Cycle or Citric Acid Cycle: Steps, Products, Significance. (n.d.). BYJUS. Retrieved July 25, 2024, from https://byjus.com/neet/krebs- CLINICAL CHEMISTRY 2 cycle/ TISSUE SOURCES ASPARTATE AMINOTRANSFERASE (AST) ▪ High Concentrations: ▪ Cardiac Tissue ▪ Liver ▪ Skeletal Muscle ▪ Lower Concentrations: ▪ Kidney ▪ Pancreas ▪ Erythrocytes SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Bishop, M. L., Fody, E. P., & Schoeff, L. E. (2018). Clinical chemistry: Principles, procedures, correlations (Enhanced 8th ed). Jones & Bartlett. CLINICAL CHEMISTRY 2 DIAGNOSTIC SIGNIFICANCE ASPARTATE AMINOTRANSFERASE (AST) ▪ Acute Hepatocellular Disorders ▪ Highest levels observed ▪ In viral hepatitis: up to 100 times ULN ▪ In cirrhosis: approximately 4 times ULN ▪ Skeletal Muscle Involvement ▪ Levels increase (4-8× ULN) ▪ Acute Myocardial Infarction (AMI) SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Bishop, M. L., Fody, E. P., & Schoeff, L. E. (2018). Clinical chemistry: Principles, procedures, correlations (Enhanced 8th ed). Jones & Bartlett. CLINICAL CHEMISTRY 2 DIAGNOSTIC SIGNIFICANCE ASPARTATE AMINOTRANSFERASE (AST) MARKERS OF ACUTE MYOCARDIAL INFARCTION Starts to increase Peaks Normalize Myoglobin 1-3 hours 5-12 hours 18-30 hours Troponin T 3-4 hours 10-24 hours 7 days Troponin I 3-6 hours 12-18 hours 5-10 days CK 4-6 hours 12-24 hours 2-3 days AST 6-8 hours 18-24 hours 4-5 days LD 12-24 hours 48-72 hours 10 days SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Bishop, M. L., Fody, E. P., & Schoeff, L. E. (2018). Clinical chemistry: Principles, procedures, correlations (Enhanced 8th ed). Jones & Bartlett. CLINICAL CHEMISTRY 2 ISOENZYMES ASPARTATE AMINOTRANSFERASE (AST) ▪ AST Isoenzymes: ▪ Cytoplasmic Isoenzyme ▪ predominant in serum ▪ Mitochondrial Isoenzyme ▪ increased in cellular necrosis ▪ Concentration: ▪ Intracellular AST: 7,000 times higher than extracellular ▪ Clinical Analysis: ▪ Isoenzyme analysis not routinely performed SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Bishop, M. L., Fody, E. P., & Schoeff, L. E. (2018). Clinical chemistry: Principles, procedures, correlations (Enhanced 8th ed). Jones & Bartlett. CLINICAL CHEMISTRY 2 ▪ McPherson, Richard A. and Pincus, Matthew R., "Henry's Clinical Diagnosis and Management by Laboratory Methods, 24th ed" (2021). ASSAY FOR ENZYME ACTIVITY ASPARTATE AMINOTRANSFERASE (AST) ▪ Principle: ▪ Based on Karmen Method ▪ Uses a coupled enzymatic reaction ▪ Indicator: ▪ Malate Dehydrogenase ▪ Monitors absorbance change at 340 nm ▪ Measures NADH oxidation to NAD+ ▪ Optimal pH Range:7.3 to 7.8 ▪ Reference range: 5 to 35 U/L (37°C) (0.1 to 0.6 µkat/L) AST Aspartate + α−ketoglutarate Oxaloacetate + Glutamate + MD Oxaloacetate + NADH + H Malate + NAD + SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Bishop, M. L., Fody, E. P., & Schoeff, L. E. (2018). Clinical chemistry: Principles, procedures, correlations (Enhanced 8th ed). Jones & Bartlett. CLINICAL CHEMISTRY 2 SOURCE OF ERROR ASPARTATE AMINOTRANSFERASE (AST) ▪ Hemolysis: ▪ Can dramatically increase serum AST concentration ▪ Should be avoided to ensure accurate results ▪ Stability: ▪ Stable in serum for 3 to 4 days ▪ Optimal at refrigerated temperatures SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Bishop, M. L., Fody, E. P., & Schoeff, L. E. (2018). Clinical chemistry: Principles, procedures, correlations (Enhanced 8th ed). Jones & Bartlett. CLINICAL CHEMISTRY 2 PACKAGE INSERT ASPARTATE AMINOTRANSFERASE (AST) SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE CLINICAL CHEMISTRY 2 PACKAGE INSERT ASPARTATE AMINOTRANSFERASE (AST) SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE CLINICAL CHEMISTRY 2 PACKAGE INSERT ASPARTATE AMINOTRANSFERASE (AST) SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE CLINICAL CHEMISTRY 2 PACKAGE INSERT ASPARTATE AMINOTRANSFERASE (AST) SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE CLINICAL CHEMISTRY 2 SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE CLINICAL CHEMISTRY 2 ALANINE AMINOTRANSFERASE NOMENCLATURE & FUNCTION ALANINE AMINOTRANSFERASE (ALT) ▪ E.C. 2.6.1.2 ▪ L-Alanine 2-Oxaloglutarate Aminotransferase ▪ Formerly: Serum Glutamic Pyruvic Transaminase (SGPT) ▪ Catalyzes the transfer of an amino group from alanine to α- ketoglutarate ▪ Produces glutamate and pyruvate ▪ Coenzyme: Pyridoxal phosphate (Vitamin B6) SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Bishop, M. L., Fody, E. P., & Schoeff, L. E. (2018). Clinical chemistry: Principles, procedures, correlations (Enhanced 8th ed). Jones & Bartlett. CLINICAL CHEMISTRY 2 TISSUE SOURCE ALANINE AMINOTRANSFERASE (ALT) ▪ ALT is distributed in many tissues, with comparatively high concentrations in the liver. ▪ More liver-specific SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Bishop, M. L., Fody, E. P., & Schoeff, L. E. (2018). Clinical chemistry: Principles, procedures, correlations (Enhanced 8th ed). Jones & Bartlett. CLINICAL CHEMISTRY 2 DIAGNOSTIC SIGNIFICANCE ALANINE AMINOTRANSFERASE (ALT) ▪ Primary Use: ▪ Evaluation of hepatic disorders ▪ Higher elevations in hepatocellular disorders ▪ Lower elevations in extrahepatic or intrahepatic obstructive disorders ▪ Acute Liver Inflammation: ▪ ALT elevations often higher than AST ▪ ALT remains elevated longer due to a longer half-life (16-24 hours vs. AST) ▪ Comparison with AST: ▪ Helps determine the source of elevated AST ▪ Detects concurrent liver involvement with myocardial injury SAN PEDRO COLLEGE SCHOOL OF MEDICAL LABORATORY SCIENCE REFERENCES: ▪ Bishop, M. L., Fody, E. P., & Schoeff, L. E. (2018). Clinical chemistry: Principles, procedures, correlations (Enhanced 8th ed). Jones & Bartlett. CLINICAL CHEMISTRY 2 DIAGNOSTIC SIGNIFICANCE ALANINE AMINOTRANSFERASE (ALT) ▪ Alcohol-Induced Liver Injury: ▪ Elevated AST/ALT ratio (De Ritis ratio) of 3 to 4:1 ▪ Mitochondrial AST has a longer half- life ▪ AST:ALT ratio ▪ Carcinoma, ALD, Cirrhosis ▪ Chronic Liver Conditions: of the liver = >2 ▪ In cirrhosis, AST often higher than ALT ▪ Hepatitis =