Drug Metabolism in the Liver

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Questions and Answers

What is the primary function of the liver's drug-metabolizing system?

To store fat-soluble vitamins

To produce bile acids

To synthesize serum albumin

To modify drugs for easier elimination from the body (correct)

Which of the following is NOT a process involved in drug detoxification by the liver?

Oxidation

Hydroxylation

Demethylation

Fermentation (correct)

How much bile is produced by the liver each day?

3 liters (correct)

4 liters

2 liters

1 liter

What substances are included in bile?

Bile acids, pigments, and cholesterol Signup and view all the answers

Which metabolic product is NOT detoxified by the liver?

Urea Signup and view all the answers

What type of hyperbilirubinemia is primarily associated with hemolytic anemia?

Unconjugated hyperbilirubinemia Signup and view all the answers

Which bilirubin type is not water soluble and primarily bound to albumin?

Unconjugated bilirubin Signup and view all the answers

In hepatic hyperbilirubinemia, bilirubin levels depend on what factor?

Underlying cause of liver disease Signup and view all the answers

What is a common cause of post-hepatic hyperbilirubinemia?

Gallstones Signup and view all the answers

Which condition is associated with the presence of urine bilirubin?

Post-hepatic hyperbilirubinemia Signup and view all the answers

What measurement is typically elevated in post-hepatic hyperbilirubinemia?

Conjugated bilirubin Signup and view all the answers

Which statement accurately describes pre-hepatic hyperbilirubinemia?

It leads to increased production of unconjugated bilirubin. Signup and view all the answers

What type of bilirubin predominates in post-hepatic conditions?

Conjugated bilirubin Signup and view all the answers

What is the primary enzyme deficiency in Crigler-Najjar Syndrome Type 1?

Glucoronyl transferase (UDGT) Signup and view all the answers

What distinguishes Gilbert’s Syndrome in terms of bilirubin levels?

Total bilirubin usually ranges from 1.5 to 3.0 mg/dL Signup and view all the answers

Which syndrome is associated with a complete absence of conjugated bilirubin production?

Crigler-Najjar Syndrome Type 1 Signup and view all the answers

What is the primary clinical feature of Dubin-Johnson Syndrome?

Blockage of bilirubin excretion Signup and view all the answers

What is a common treatment for infants with Crigler-Najjar Syndrome?

Phototherapy Signup and view all the answers

Which syndrome results in the accumulation of lipofuscin pigment in the liver?

Rotor Syndrome Signup and view all the answers

What indicates the extent of liver damage in the enzyme test?

Liberation of various enzymes Signup and view all the answers

Which of the following is NOT a characteristic of Gilbert's Syndrome?

Conjugation deficit Signup and view all the answers

What is the preferred specimen for the Evelyn-Malloy method?

Serum Signup and view all the answers

Which condition is characterized by yellow discoloration of the skin and sclera?

Icterus Signup and view all the answers

What is the effect of hemolysis on bilirubin concentration measurement?

Decreases the concentration Signup and view all the answers

What happens to bilirubin measurement if the serum sample is exposed to light?

Decrease by 30-50% Signup and view all the answers

What does an increase in alkaline phosphatase (ALP) indicate in the context of jaundice?

Obstructive jaundice Signup and view all the answers

Which bilirubin type is typically increased in pre-hepatic jaundice?

Unconjugated bilirubin Signup and view all the answers

What is the characteristic urinary finding in post-hepatic jaundice?

Positive urine bilirubin Signup and view all the answers

Which condition indicates failure of bile flow to the intestine?

Post-hepatic jaundice Signup and view all the answers

What could cause lipemia to affect bilirubin measurement?

Increase measured bilirubin concentration Signup and view all the answers

What type of jaundice is associated with increased total bilirubin and normal urobilinogen?

Post-hepatic jaundice Signup and view all the answers

What is the primary source of ammonia in the body?

Deamination of amino acids Signup and view all the answers

Which liver condition is characterized by scars in the liver tissue?

Cirrhosis Signup and view all the answers

Which symptom is NOT typically associated with deteriorating liver function?

Increased appetite Signup and view all the answers

What is the normal range for ammonia levels in the blood?

19-60 ug/dl Signup and view all the answers

Which condition is NOT a known cause of increased ammonia levels?

Diabetes Mellitus Signup and view all the answers

What type of liver cancer begins within liver cells?

Hepatocellular carcinoma Signup and view all the answers

Which approach is NOT a treatment option for alcohol-related cirrhosis?

Use of corticosteroids Signup and view all the answers

Which substance is primarily associated with neurotoxicity in hepatic failure?

Ammonia Signup and view all the answers

Which of the following is a benign tumor that can occur in the liver?

Hepatocellular adenoma Signup and view all the answers

Increased ammonia levels can lead to which neurological condition?

Encephalopathy Signup and view all the answers

Study Notes

Drug-Metabolizing System of the Liver

Modifies drugs for efficient elimination from the body.
Detoxification processes include oxidation, reduction, hydrolysis, hydroxylation, carboxylation, and demethylation.
Most detoxification reactions occur in liver microsomes via cytochrome P-450 isoenzymes.

Bile Composition and Production

Composed of bile acids, bile pigments, cholesterol, and other substances extracted from blood.
The liver produces approximately 3 liters of bile per day, with 1 liter excreted.

Storage Functions of the Liver

Stores all fat and water-soluble vitamins, along with glycogen.

Hepatic Synthetic Function Tests

Serum albumin and total protein assessments (TPAG: Total Protein, Albumin, Globulin) are useful for evaluating liver function.
Vitamin K factors II, VII, IX, and X are indicators of hepatic synthetic function.

Bilirubin Metabolism

Bilirubin is the end product of hemoglobin metabolism and is the principal pigment in bile.
Pre-hepatic, hepatic, and post-hepatic stages of hyperbilirubinemia help classify jaundice:
- Pre-Hepatic: Unconjugated hyperbilirubinemia often caused by hemolytic anemia; bilirubin rarely exceeds 5 mg/dL.
- Hepatic: Can show both conjugated or unconjugated hyperbilirubinemia, with levels varying depending on specific liver diseases (e.g., hepatitis, cirrhosis).
- Post-Hepatic: Conjugated hyperbilirubinemia due to biliary obstruction commonly caused by gallstones or tumors.

Specimen Collection and Storage

Serum is the specimen of choice for bilirubin testing.
Fasting samples preferred; lipemia can interfere with bilirubin measurement.
Specimens can be stored at room temperature for 2 days or indefinitely at -20°C.

Jaundice Classification

Jaundice is the yellow discoloration of skin and mucous membranes due to elevated bilirubin levels:
- Unconjugated Hyperbilirubinemia: Pre-hepatic jaundice results from increased RBC destruction.
- Conjugated Hyperbilirubinemia: Post-hepatic jaundice due to inability to excrete bilirubin, typically caused by gallstones.

Syndromes Affecting Bilirubin Levels

Gilbert’s Syndrome: Increased unconjugated bilirubin (1.5 - 3.0 mg/dL).
Crigler-Najjar Syndrome: Complete or partial deficiency of glucuronyl transferase, leading to increased unconjugated bilirubin.
Dubin-Johnson & Rotor Syndromes: Impaired excretion of conjugated bilirubin resulting in increased levels.

Tests for Liver Detoxification Function

Enzyme tests measure liver damage through the release of specific enzymes.
Ammonia levels indicate detoxification ability, with increased levels suggesting liver failure or hepatic coma.

Liver Diseases and Their Effects

Cirrhosis: Scar tissue disrupts blood flow and liver function; can be caused by chronic hepatitis or alcohol abuse.
Liver Tumors: Primary liver cancer (hepatocellular carcinoma) and metastatic cancer from other body parts (e.g., colon, lung).
Hepatitis: Inflammation due to viral infection or other causes can lead to liver damage.
Reye’s Syndrome: Associated with liver dysfunction and fatty liver changes, typically following viral infections.

Key Indicators of Liver Function

Increased serum enzymes such as ALP, aminotransferases, and GGT indicate liver injury.
Elevated ammonia signifies impaired detoxification, revealing risk for hepatic issues.

Conclusions

Liver plays a critical role in detoxification, drug metabolism, bile production, and storage.
Various syndromes and diseases can significantly affect liver function and associated biomarkers.

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Description

Explore the intricate drug-metabolizing system of the liver, which is crucial for detoxifying various substances. This quiz covers processes such as oxidation, reduction, and the role of cytochrome P-450 isoenzymes in drug elimination.