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Questions and Answers
Which of the following statements about albumin synthesis is correct?
Which of the following statements about albumin synthesis is correct?
What happens to the albumin/globulin (A/G) ratio in chronic liver disease?
What happens to the albumin/globulin (A/G) ratio in chronic liver disease?
What is the half-life of prothrombin, a marker of liver function?
What is the half-life of prothrombin, a marker of liver function?
Which of the following is a consequence of significant liver damage regarding prothrombin time (PT)?
Which of the following is a consequence of significant liver damage regarding prothrombin time (PT)?
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Why is a single liver function test considered of little value for screening liver conditions?
Why is a single liver function test considered of little value for screening liver conditions?
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What does a rise in ALT and AST levels typically indicate?
What does a rise in ALT and AST levels typically indicate?
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Under which condition would you expect elevated ALP levels alongside GGT?
Under which condition would you expect elevated ALP levels alongside GGT?
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What would a low albumin level in liver function tests suggest?
What would a low albumin level in liver function tests suggest?
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Which of the following is NOT a use of liver function tests?
Which of the following is NOT a use of liver function tests?
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Which lab value may be influenced by liver synthesis impairment?
Which lab value may be influenced by liver synthesis impairment?
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Which of the following is NOT a function of the liver?
Which of the following is NOT a function of the liver?
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What is the primary role of Alanine Aminotransferase (ALT) in the liver?
What is the primary role of Alanine Aminotransferase (ALT) in the liver?
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Which enzyme is indicative of hepatocyte injury?
Which enzyme is indicative of hepatocyte injury?
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What is the primary metabolic process where the liver synthesizes glucose from non-carbohydrate sources?
What is the primary metabolic process where the liver synthesizes glucose from non-carbohydrate sources?
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Which liver function test is primarily used to assess synthetic function?
Which liver function test is primarily used to assess synthetic function?
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In which of the following functions is the liver NOT involved?
In which of the following functions is the liver NOT involved?
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What role does the liver play in detoxification?
What role does the liver play in detoxification?
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Which substances are primarily stored in the liver?
Which substances are primarily stored in the liver?
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Which enzyme is primarily useful for excluding bone disease when elevated?
Which enzyme is primarily useful for excluding bone disease when elevated?
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What does a high level of GGT indicate in patients with liver dysfunction?
What does a high level of GGT indicate in patients with liver dysfunction?
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In the context of jaundice, what is implied by the presence of both indirect and direct bilirubin in plasma?
In the context of jaundice, what is implied by the presence of both indirect and direct bilirubin in plasma?
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Which type of jaundice involves elevated direct bilirubin in urine?
Which type of jaundice involves elevated direct bilirubin in urine?
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What symptom is most clearly associated with hyperbilirubinemia levels greater than 2 mg/dl?
What symptom is most clearly associated with hyperbilirubinemia levels greater than 2 mg/dl?
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Which bodily fluid is expected to appear normal (absent bilirubin) in cases of prehepatic jaundice?
Which bodily fluid is expected to appear normal (absent bilirubin) in cases of prehepatic jaundice?
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In a patient with elevated levels of alkaline phosphatase (ALP), what does an elevated GGT level suggest?
In a patient with elevated levels of alkaline phosphatase (ALP), what does an elevated GGT level suggest?
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What is the expected level of urobilinogen in urine for a healthy individual?
What is the expected level of urobilinogen in urine for a healthy individual?
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Which condition is likely associated with a marked increase in ALT levels over 300 IU/L?
Which condition is likely associated with a marked increase in ALT levels over 300 IU/L?
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An AST/ALT ratio greater than 3:1 is highly suggestive of which condition?
An AST/ALT ratio greater than 3:1 is highly suggestive of which condition?
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Which enzyme elevation is not typically associated with bone disease?
Which enzyme elevation is not typically associated with bone disease?
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Which of the following conditions are likely to show a moderate increase in AST levels?
Which of the following conditions are likely to show a moderate increase in AST levels?
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What does a high level of alkaline phosphatase (ALP) indicate in preterm infants?
What does a high level of alkaline phosphatase (ALP) indicate in preterm infants?
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In cases of cholestasis, which test might show elevated levels indicative of intrahepatic or extrahepatic damage?
In cases of cholestasis, which test might show elevated levels indicative of intrahepatic or extrahepatic damage?
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Which condition is likely to show an increase in both AST and ALT levels but with AST being higher?
Which condition is likely to show an increase in both AST and ALT levels but with AST being higher?
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Which of the following causes is associated with an increase in alkaline phosphatase (ALP) due to bone disease?
Which of the following causes is associated with an increase in alkaline phosphatase (ALP) due to bone disease?
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Study Notes
Liver Function Tests
- Liver function tests are used to assess liver health and identify potential issues.
- These tests evaluate different aspects of liver function, including injury, synthesis, and excretion.
Normal Liver Functions
- Metabolism: The liver plays a vital role in carbohydrate, lipid, and protein metabolism.
- Storage: The liver stores vitamins (like K, D, A, and B12) and iron.
- Excretory Function: The liver excretes bilirubin and other substances.
- Detoxification: The liver detoxifies drugs and ammonia.
- Hematological Functions: The liver is involved in blood formation (fetal life and proerythropoietin in adults), blood coagulation, and blood volume regulation.
Liver Function Tests and Their Interpretation
- Liver function tests are categorized into three groups:
- Hepatocyte injury: Assessed using AST and ALT. Elevated levels indicate damage to the liver cells.
- Synthetic function: Evaluated using albumin and prothrombin time (PT). Low levels can suggest liver damage.
- Cholestasis or Excretory function: Assessed using bilirubin, ALP, and GGT. Elevated levels may indicate issues with bile flow.
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Enzymes: Grouped into two categories:
- Enzymes that reflect hepatocyte damage: Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT).
- Enzymes showing cholestasis: Alkaline phosphatase (ALP), Gamma-glutamyl transpeptidase (GGT), and 5'–nucleotidase.
Uses of Liver Function Tests
- Screening: Liver function tests are non-invasive and a sensitive screening method for detecting liver dysfunction.
- Disease pattern recognition: These tests can differentiate between various liver diseases like acute viral hepatitis, chronic liver disease (CLD), and cholestatic disorders.
- Severity assessment: Used to assess the severity and predict the outcome of specific liver diseases.
- Follow-up and treatment evaluation: Monitor the progression of liver diseases and the response to treatment.
Enzymes (Details)
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Alanine transaminase (ALT): Elevated levels specifically indicate liver damage.
- It is more specific to the liver than AST.
- Its source: liver > heart > kidney > skeletal muscle > spleen
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Causes of high ALT:
- Acute viral hepatitis, Toxic liver necrosis
- Liver cirrhosis, Cholestatic jaundice
- Liver congestion, Alcoholic Hepatitis, and Malignant liver infiltration
- Chronic viral hepatitis, Hemochromatosis, Fatty liver.
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Aspartate aminotransferase (AST): Elevated levels indicate liver damage but can also originate from other organs like the heart.
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Causes of high AST:
- Physiological (newborns), Liver cirrhosis, Cholestatic jaundice, Malignant liver infiltration, Skeletal muscle and Myocardial infarction
- Acute viral hepatitis, Toxic liver necrosis
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Causes of high AST:
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Alkaline phosphatase (ALP): Elevated levels indicate cholestasis (obstruction of bile flow).
- Causes of high ALP: Pregnancy, Children (higher osteoblastic activity), Preterm infants (higher ALP levels), Medication (e.g., sulfonamides), Primary biliary cirrhosis, Stones, Malignancy, Pancreatitis
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Gamma-glutamyl transpeptidase (GGT): A sensitive marker for cholestasis, cirrhosis, and carcinoma. Useful in excluding bone disease and often elevated with alcohol toxicity.
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5' Nucleotidase: Another specific test for cholestasis or damage to intra or extra hepatic biliary system levels.
Bilirubin
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Bilirubin is a breakdown product of red blood cells.
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Elevated bilirubin levels can lead to hyperbilirubinemia and jaundice.
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Types: Direct (conjugated) and indirect (unconjugated).
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Elevated direct bilirubin suggests problems with the biliary system.
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Elevated indirect bilirubin suggests problems with red blood cell breakdown.
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Increased bilirubin levels cause dark urine, light-colored stools.
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Clinical Classifications of Hyperbilirubinemia/Jaundice: Categorized as prehepatic, hepatic, or posthepatic (obstructive). These classifications differentiate based on which stage of bilirubin processing is affected.
Plasma Proteins
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The liver is the major source of most plasma proteins, including albumin and globulins (α, β and γ).
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Albumin: Synthesized exclusively by the liver. 40-60% of total plasma protein.
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Globulins: Synthesized primarily by the liver (α and β). elevated gamma globulins could be chronic hepatitis or cirrhosis (IgG in autoimmune & IgA in alcoholic liver disease).
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A/G Ratio: The ratio of albumin to globulin. It helps diagnose liver disease, typically a 2:1 ratio is normal.
Prothrombin Time (PT)
- PT measures the time it takes for blood to clot.
- The liver is essential for producing clotting factors.
- Low albumin and prolonged PT suggest significant liver damage as the liver produces clotting factors.
- Low albumin and prolonged PT suggest significant liver damage. Vitamin K deficiency causes prolonged PT
Liver Function Test Normal Values (Approximate)
- Specific values can vary. Consult lab reports for precise details.
- This table provides general normal ranges for common liver function tests and should not be taken as definitive.
Algorithms for Liver Disease Diagnosis
- Algorithms using liver function tests help determine the type of liver disease, if the underlying cause appears to be hepatocellular or cholestatic.
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Description
Test your knowledge about liver function tests with this comprehensive quiz. Explore important concepts such as albumin synthesis, prothrombin levels, and the implications of altered liver function test results. Ideal for students and professionals interested in hepatology.
