Liver Function Tests Overview
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Questions and Answers

What does an increased level of alanine aminotransferase (ALT) most likely indicate?

  • Hepatocyte injury (correct)
  • Increased hepatic blood flow
  • Liver regeneration
  • Cholestasis

    • Which of the following liver function tests is primarily used to assess the liver's capacity for synthetic function?

  • AST levels
  • ALT levels
  • Lactate dehydrogenase (LDH)
  • Prothrombin time (PT) (correct)

    • A prolonged INR is most indicative of which liver condition?

  • Acute liver dysfunction (correct)
  • Chronic malnutrition
  • Renal disease
  • Fatty liver

    • Which condition is characterized by an AST/ALT ratio greater than 2?

    <p>Alcoholic liver disease</p> Signup and view all the answers

    Which of the following factors can cause low serum albumin levels other than chronic liver disease?

    <p>Third spacing</p> Signup and view all the answers

    What does an elevation in lactate dehydrogenase (LDH) signal?

    <p>Nonspecific hepatic injury</p> Signup and view all the answers

    How is hepatocellular injury typically quantified in Liver Function Tests?

    <p>By evaluating aminotransferase levels</p> Signup and view all the answers

    In chronic liver disease, a serum albumin level lower than which threshold generally indicates a more serious condition?

    <p>2.5 g/dL</p> Signup and view all the answers

    Which liver test would you utilize to monitor the balance between coagulation and anticoagulation factors?

    <p>INR</p> Signup and view all the answers

    Which of the following tests is least specific for liver function but indicates hepatocyte injury?

    <p>LDH</p> Signup and view all the answers

    Which condition is likely to elevate glutathione-S-transferase levels in the context of liver injury?

    <p>Drug-induced hepatotoxicity</p> Signup and view all the answers

    What does a total bilirubin level greater than 3 mg/dL typically indicate?

    <p>Evidence of jaundice</p> Signup and view all the answers

    Which of the following is true regarding alkaline phosphatase in cholestatic disease?

    <p>Values can be 2-4 times normal</p> Signup and view all the answers

    What is the relationship between indirect bilirubin and hemolysis?

    <p>Indirect bilirubin is lipid soluble</p> Signup and view all the answers

    In cases of liver failure, what might a decrease in certain liver enzyme levels indicate?

    <p>Possible decline in hepatocyte function</p> Signup and view all the answers

    Which type of bilirubin is elevated due to bile duct obstruction?

    <p>Direct (conjugated) bilirubin</p> Signup and view all the answers

    Which enzyme is considered nonspecific for liver dysfunction as it is found in extrahepatic tissues?

    <p>Alkaline phosphatase</p> Signup and view all the answers

    What other conditions can lead to elevated lactate dehydrogenase (LDH) levels aside from liver dysfunction?

    <p>Rhabdomyolysis</p> Signup and view all the answers

    Which of the following statements about bilirubin is FALSE?

    <p>Indirect bilirubin is water-soluble</p> Signup and view all the answers

    What is a key characteristic of glutathione-S-transferase as a biomarker?

    <p>Sensitive for acute liver injury</p> Signup and view all the answers

    Study Notes

    Liver Function Tests (LFTs)

    • LFTs do not directly measure liver function, particularly ALT and AST.
    • Abnormalities in LFTs often appear late in the progression of hepatic disease.
    • LFT abnormalities primarily reflect hepatocellular injury rather than liver function.

    LFTs and Liver Function Assessment

    • LFTs help define the type of liver pathology when combined with clinical assessment.

    Synthetic Function

    • Prothrombin Time (PT): Measures the activity of clotting factors (fibrinogen, prothrombin, and factors V, VII, and X).
      • A normal PT range is 11-14 seconds.
      • A prolonged PT usually indicates liver dysfunction, affecting the balance between coagulation and anticoagulation factors.
    • Albumin: Evaluates chronic liver disease and hepatocellular function (protein synthesis).
      • Albumin levels below 2.5-3 g/dL generally suggest a chronic problem.
      • Low albumin levels can be seen in malnutrition, renal losses, and third-spacing.
    • International Normalized Ratio (INR), Serum Cholesterol, Plasma Pseudocholinesterase:
      • INR: A prolonged INR indicates impaired liver function.
      • These tests contribute to a more comprehensive evaluation of liver function.

    Hepatocellular Injury

    • Aminotransferases (AST and ALT):
      • Alanine Aminotransferase (ALT): Primarily found in the liver.
      • Aspartate Aminotransferase (AST): Found in both liver and non-hepatic tissues.
        • Isolated ALT elevation can originate from non-liver sources (heart, muscle, brain, kidney, pancreas, adipose tissue, blood).
      • Mild aminotransferase elevation: Indicates any hepatocyte injury, including fatty liver or infection.
      • Large elevations: Suggest massive hepatic necrosis, fulminant viral hepatitis, drug-induced liver injury, or shock liver.
      • AST/ALT Ratio: May differentiate alcoholic liver disease (AST 2-3 times greater than ALT).
    • Lactate Dehydrogenase (LDH):
      • A nonspecific marker of hepatic injury.
      • Extreme elevations are seen in ischemia or drug-induced hepatotoxicity, especially acetaminophen overdose, often accompanied by elevated AST/ALT.
      • Extrahepatic disorders like hemolysis, rhabdomyolysis, tumor necrosis, renal infarction, and acute stroke can also increase LDH.
    • Glutathione-S-Transferase (GST):
      • A sensitive marker for liver injury.
      • Short half-life and rapid increase with liver injury.
      • Can be used to monitor improvement in liver function.

    Cholestatic Disorders

    • Bilirubin:
      • Breakdown product of hemoglobin.
      • Indicates liver's excretory function.
      • Normal total bilirubin is less than 1.5 mg/dL.
      • Jaundice is usually visible when total bilirubin persistently exceeds 3 mg/dL.
      • Direct Bilirubin (Conjugated): Water-soluble, elevated in bile duct blockage or obstruction.
      • Indirect Bilirubin (Unconjugated): Lipid-soluble, elevated in hemolysis or cirrhosis.
    • Hepatic Clearance:
      • Alkaline Phosphatase (AP):
        • Mild elevations may be within normal range.
        • A nonspecific marker found in extrahepatic tissues.
        • Values 2-4 times normal are seen in cholestatic disease.
        • Can indicate intrahepatic or extrahepatic biliary obstruction.
      • Y Glutamyl Transpeptidase (GTTP):
      • 5' Nucleotidase (5'-NT):

    Interpretation of Liver Function Tests

    • In liver failure, improving LFT values may not indicate actual improvement. It could suggest that there are no more functional hepatocytes.

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    Related Documents

    Liver Function Tests Study Guide PDF

    Description

    This quiz covers key concepts related to Liver Function Tests (LFTs), including their role in assessing liver pathology and synthetic function. It also discusses the implications of measurement parameters like Prothrombin Time and Albumin levels in diagnosing liver conditions.

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