Approach to Liver Function Test

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Approach to Liver Function Test

• Dr Yasir M Khayyat,MBcHB,FRCPC,FACP

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Before you order LFT ask
600 ????
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Hepatocellular Necrosis Markers
Markers of synthetic function
INR
Markers of Cholestasis

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Liver cell
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Liver cell
AST ALT
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• ALT
• Specific from the liver ,Cytosolic Enzyme
• AST
• Muscle(skeletal , Cardiac),Brain,Kidney,Pancreas,
  cytoslic 20 and mitochondrial 80.
• Levels are normal in advanced cirrhosis
• AST/ALT ratio
• Acute liver injury 1 , Alcoholic hepatitis gt 2
• Its elevation does not correlate with hepatic
  necrosis.

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• In Alcoholic liver disease
• AST ? Alcohol increase release of mitochondrial
  AST
• ALT ? in alcohol there is pyridoxal 5 deficiency
  with decrease in ALT gt AST activity
• In NAFLD,chronic liver disease
• AST ( early low ,then with progressive disease
  and cirrhosis increase) , advanced cirrhosis ?
  decrease hepatic clearance of AST.
• ALT

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• Alkaline phosphatase
• From Liver,Bone,Kidney,placenta,leukocytes,various
  neoplasms.
• From the apical membrane of the hepatocyte and
  luminal domain of the bile duct.
• Predominantly in infiltrative hepatic
  disorders, biliary obstruction ,extrahepatic
  biliary tree obstruction.
• Due to increased de novo synthesis rather than
  release of the stored enzyme or impaired
  clearance
• GGT ( Gamma Glutamyl Transpeptidase)
• From kidney,spleen,pancreas,heart,lung,brain

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• Bilirubin
• Conjugated Bilirubin
• Unconjugated Bilirubin
• Markers of Hepatic Synthesis
• INR or PT
• The liver is factory for all coagulation factors
  except 8.
• INR if dependant on Vit K ( 2,7,9,10)
• Increased in vitamin K deficiency(
  malnutrition-malabsorption-antibiotic
  use)warfarin use, consumptive coagulpathy.

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• Albumin
• Synthesize 10g by the liver daily. It is not only
  reflect liver status but it reflects nutritional
  and volume status, vascular integrity,catabolism,h
  ormonal factors, loss in the urine or stool.

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Non Hepatic causes of abnormal lft
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Hepatocellular necrosis
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Cholestasis
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Hepatic granulomas
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Think about the causes of liver disesase