Liver Function in Biochemistry: Quizzes and Flashcards

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Questions and Answers

What is the primary function of liver function tests?

To evaluate the response to therapy in liver disease

To provide a specific diagnosis of liver disease

To assess the severity of liver disease

To detect the presence of liver disease and distinguish among different types of liver disorders (correct)

Which of the following enzymes is a biomarker of liver injury?

Alkaline phosphatase (ALP)

Alanine aminotransferase (ALT) (correct)

5’nucleotidase

Gamma glutamyl transferase (GGT)

What is a characteristic of the liver that makes it difficult to detect liver disease early?

It is highly susceptible to injury

It is difficult to biopsy

It has a high functional reserve (correct)

It has a low functional reserve

What is the primary advantage of liver function tests?

They are non-invasive and widely available Signup and view all the answers

Which of the following is NOT a function of liver function tests?

Providing a definitive diagnosis of liver disease Signup and view all the answers

What is the primary role of aspartate aminotransferase (AST) in liver function tests?

It is a biomarker of liver injury Signup and view all the answers

What is the primary function of albumin in the transport of bilirubin to the liver?

To tightly bind to bilirubin and transport it to the liver Signup and view all the answers

What is required for the uptake of unconjugated bilirubin by the hepatocyte?

Inorganic anions Signup and view all the answers

What is the site of bilirubin conjugation in the hepatocyte?

Smooth endoplasmic reticulum Signup and view all the answers

What is the end product of bilirubin conjugation in the liver?

Both bilirubin monoglucuronide and bilirubin diglucuronide Signup and view all the answers

What is the direction of conjugated bilirubin transport into the bile canaliculi?

Uni-directional Signup and view all the answers

What is the rate-limiting step in bilirubin metabolism?

Secretion of conjugated bilirubin into the bile canaliculi Signup and view all the answers

What is the primary source of Aspartate Aminotransferase in the body?

Heart, liver, skeletal muscle, and kidney Signup and view all the answers

What is the significance of an ALT level above 1000 IU/mL?

Extensive hepatocellular damage Signup and view all the answers

What is the normal reference interval for ALT in serum for males?

6-21 IU/mL Signup and view all the answers

In acute hepatitis, what is the typical relationship between ALT and AST levels?

ALT is more increased than AST Signup and view all the answers

What is the primary source of Alanine Aminotransferase in the liver?

Cytosol only Signup and view all the answers

What is the significance of a serum AST level in the diagnosis of disease?

Useful in the diagnosis of MI, liver disorders, and muscle damage Signup and view all the answers

What is the site of AST release into serum in severe hepatocellular injury?

Mitochondrial membrane Signup and view all the answers

Which of the following conditions is associated with a relatively greater increase in plasma ALT than AST activities?

Inflammatory or infective conditions Signup and view all the answers

What is the usual sample taken for the liver function test?

Blood sample Signup and view all the answers

In Wilson disease, which organs are affected by copper accumulation?

Liver, brain, and eyes Signup and view all the answers

In infiltrative diseases such as colon cancer that spread to the liver, what is the relationship between ALT and AST?

AST > ALT Signup and view all the answers

What is the primary effect of copper accumulation in the liver in Wilson disease?

Hepatocellular injury Signup and view all the answers

In which of the following conditions is the plasma alkaline phosphatase level usually increased to more than three times the upper limit of normal?

Obstructive cholestasis Signup and view all the answers

What is the usual reason for mild cholestasis in hepatocellular diseases?

Obstruction of bile canaliculi by swollen hepatocytes Signup and view all the answers

What is the primary site of synthesis of gamma-glutamyl transferase (GGT)?

Liver Signup and view all the answers

What is the normal reference interval for GGT in serum?

10-70 U/L Signup and view all the answers

Which of the following enzymes is induced by ethanol and anticonvulsant drugs?

Gamma-glutamyl transferase Signup and view all the answers

What is the significance of a mildly elevated alkaline phosphatase level in hepatocellular diseases?

It indicates mild cholestasis Signup and view all the answers

Study Notes

Liver Function Tests Overview

Liver function tests (LFTs) are a group of clinical biochemistry laboratory blood assays that provide information about the state of a patient's liver.
LFTs can detect the presence of liver disease, distinguish among different types of liver disorders, assess the severity and predict the outcome, and monitor response to therapy.

Functions of the Liver and Bilirubin Production

The liver has a considerable functional reserve, and most liver diseases cause only mild symptoms initially.
Bilirubin is produced and metabolized in the liver, and routine liver function tests include measurements of bilirubin levels.

Routine Liver Function Tests (Enzymes)

Serum enzymes in routine LFTs include:
- Alanine aminotransferase (ALT)
- Aspartate aminotransferase (AST)
- Alkaline phosphatase (ALP)
- Gamma glutamyl transferase (GGT)

ALT (Alanine Aminotransferase)

Normal reference interval in serum: 4-17 IU/mL for females and 6-21 IU/mL for males
ALT is a more specific biomarker of liver injury than AST
ALT is released into circulation in response to hepatocellular damage
High levels (>1000 IU/mL) indicate extensive hepatocellular damage (acute viral hepatitis, ischemic liver injury, toxin/drug-induced liver injury)

AST (Aspartate Aminotransferase)

Normal reference interval in serum: 7-32 U/L
AST is widely distributed in the body (heart, liver, skeletal muscle, and kidney)
Elevated AST levels can indicate liver diseases, cardiac disease, muscle damage, or hemolysis

Comparison of ALT and AST

Both ALT and AST are useful indicators of hepatocellular damage
The relative activities of the enzymes give some index of the underlying pathology and severity of the disease process
Inflammatory or infective conditions may cause a greater increase in plasma ALT than AST activities
In infiltrative disorders, there may be a proportionately greater increase in plasma AST activity than ALT

Alkaline Phosphatase (ALP)

Normal reference interval in serum: 15-105 U/L
ALP is elevated in obstructive cholestasis disease and other conditions (1° biliary cirrhosis, choledocholithiasis, hepatic malignancy, Paget's disease)
In hepatocellular diseases, ALP levels may be normal or slightly increased

Gamma Glutamyl Transferase (GGT)

Normal reference interval in serum: 10-70 U/L
GGT is a sensitive indicator of liver disease, particularly cholestatic damage
GGT levels can be induced by ethanol and anticonvulsant drugs

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Description

Test your knowledge of liver function tests, including bilirubin production and metabolism, routine tests like ALT, AST, ALP, GGT, and albumin, and their role in clinical biochemistry. This quiz covers the functions of the liver and the state of a patient's liver health.

Y1S2 011 II Biochem Liver Function Tests: Chemical Pathology and Clinical Biochemistry