Liver Function and Disorders

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Questions and Answers

Which function of the liver is primarily responsible for the conversion of ammonia into urea?

Detoxification

Deamination of amino acids (correct)

Bilirubin metabolism

Protein synthesis

What process describes the formation of glucose from non-carbohydrate sources in the liver?

Lipogenesis

Gluconeogenesis (correct)

Glycogenolysis

Glycogenesis

What role does the hepatic portal vein play in liver function?

Supplies nutrients from the gastrointestinal tract to the liver (correct)

Transports bile from the liver to the intestine

Carries oxygen-rich blood to the liver

Drains waste products from the liver

Which component is NOT part of bile produced by the liver?

Triglycerides Signup and view all the answers

The liver plays a critical role in lipid metabolism by converting carbohydrates into which of the following?

Triglycerides and fats Signup and view all the answers

What is the main genetic inheritance pattern of Gilbert Syndrome?

Autosomal recessive Signup and view all the answers

What is the primary laboratory finding in Crigler-Najjar Syndrome Type I?

Elevated total bilirubin Signup and view all the answers

Which symptom is NOT commonly associated with Dubin-Johnson Syndrome?

Severe unconjugated hyperbilirubinemia Signup and view all the answers

What is the remaining enzymatic activity of glucuronyl transferase in Gilbert Syndrome?

30% Signup and view all the answers

How does Crigler-Najjar Syndrome Type II differ from Type I?

It has normal liver enzymes Signup and view all the answers

Which of the following best describes the function of Alanine aminotransferase (ALT)?

Indicator of hepatocyte integrity and acute damage Signup and view all the answers

What is the primary clinical significance of elevated indirect (unconjugated) bilirubin?

Hemolysis and impaired liver function Signup and view all the answers

Which statement about Alkaline Phosphatase (ALP) is incorrect?

ALP is specific to liver function only. Signup and view all the answers

What condition is characterized by an excess of bilirubin greater than 50 µmol/L?

Jaundice Signup and view all the answers

Which of the following causes an increase in prothrombin time (PT)?

Impaired hepatic synthesis function Signup and view all the answers

What substance is primarily produced by the liver and has a half-life of around 20 days?

Albumin Signup and view all the answers

Which of the following conditions is NOT typically associated with an increase in Alkaline Phosphatase (ALP)?

Viral hepatitis Signup and view all the answers

What causes an increase in indirect bilirubin levels?

Impaired liver function or hemolysis Signup and view all the answers

Which condition is particularly associated with increased levels of Gamma-Glutamyl Transpeptidase (GGT)?

Alcohol ingestion Signup and view all the answers

What is a common cause of acute liver disease?

Infection Signup and view all the answers

Which type of liver disease progresses to cirrhosis as a late stage?

Nonalcoholic fatty liver disease Signup and view all the answers

What condition results from advanced cirrhosis of the liver?

Liver failure Signup and view all the answers

Which method is considered the golden standard for diagnosing liver conditions?

Liver biopsy Signup and view all the answers

What could lead to increased blood ammonia levels in acute liver disease?

Acute hepatic failure Signup and view all the answers

Which laboratory test is not recommended when platelet count is low?

Liver biopsy Signup and view all the answers

What is a primary consequence of chronic liver damage?

Progression to cirrhosis Signup and view all the answers

What is the most common symptom experienced by individuals diagnosed with hereditary hemochromatosis?

Fatigue Signup and view all the answers

Which laboratory finding is commonly associated with hereditary hemochromatosis?

Transferrin saturation of 70% or greater Signup and view all the answers

What is a distinguishing feature of Wilson disease compared to hereditary hemochromatosis?

Presence of Kayser-Fleischer rings Signup and view all the answers

What condition is NOT typically associated with hereditary hemochromatosis?

Active hepatitis Signup and view all the answers

In Wilson disease, what is the consequence of the body’s inability to excrete excess copper?

Damage to the liver and other organs Signup and view all the answers

What is the primary mode of transmission for Hepatitis A?

Fecal-oral route Signup and view all the answers

Which symptom is commonly associated with acute hepatitis?

Jaundice Signup and view all the answers

What is a potential complication of chronic Hepatitis C?

Cirrhosis Signup and view all the answers

Which laboratory test is specific for diagnosing Hepatitis B?

Hepatitis B surface antigen (HBsAg) Signup and view all the answers

Hepatitis C is primarily transmitted through which of the following?

Contaminated needles Signup and view all the answers

What percentage of adults typically recover from acute Hepatitis B within 6 months?

70% to 80% Signup and view all the answers

Which type of hepatitis virus does NOT have a vaccine available?

Hepatitis C Signup and view all the answers

What is the greatest risk period for transmission of Hepatitis A?

2 weeks before symptoms appear Signup and view all the answers

Study Notes

Liver Disorders

Liver has four lobes and hepatic lobules
Two primary sources of blood supply are hepatic artery and hepatic portal vein
Bile is collected by bile canaliculi and transported in the common hepatic duct

Functions of Liver

Metabolism of carbohydrates, lipids, and proteins
Breakdown of red blood cells (reticuloendothelial system)
Detoxification of endogenous and exogenous compounds
Bilirubin metabolism
Protein synthesis (e.g., albumin, acute phase proteins, coagulation factors)
Storage of substances

Liver and Carbohydrate Metabolism

Carbohydrate metabolism is linked to blood glucose levels
Glucose levels are largely regulated by the liver, influenced by:
- Insulin
- Glycogen
- Glucagon
- Glycogenolysis
- Gluconeogenesis

Liver and Lipid Metabolism

Lipids are water-insoluble and transported as lipoproteins
Liver produces lipoproteins, metabolizes fatty acids (acetyl-CoA) and triglycerides (energy)
Converts carbohydrates and proteins into fats
Converts cholesterol to bile
Bile is continuously produced with water, bile salts, bilirubin, fatty acids, and cholesterol

Liver and Protein Metabolism

Most important functions of liver:
- Production of plasma proteins
- Production of clotting factors
- Deamination of amino acids
- Formation of waste products (ammonia)
- Production of urea

Liver and Bilirubin Metabolism

Bilirubin is derived from hemoglobin
Unconjugated bilirubin is conjugated to glucuronic acid
High concentrations of unconjugated bilirubin can cause cell damage, jaundice, and toxicity to the brain
Total bilirubin is the sum of unconjugated and conjugated bilirubin

Liver Function Tests (LFTs)

Most LFT panels include:
- Alanine aminotransferase (ALT) (integrity of hepatocytes)
- Bilirubin
- Alkaline phosphatase (ALP) (abundant in bile canaliculi)
- Albumin

Aminotransferases

Alanine aminotransferase (ALT) test is sensitive and nonspecific; a marker of acute hepatocyte damage
Aspartate aminotransferase (AST) test is produced by hepatocytes, skeletal muscles, kidney, brain, and heart; less specific information for liver assessment

Bilirubin

Bilirubin is derived from heme
Unconjugated bilirubin is excreted in bile
Conjugated bilirubin is degraded by bacteria in the intestine to stercobilinogen
Small amounts are excreted in urine as urobilinogen
Elevated total bilirubin suggests liver disease, hemolysis, or biliary obstruction

Jaundice

Jaundice is caused by excess bilirubin
Three main causes are hemolysis (pre-hepatic), failure of hepatic conjugation mechanism (hepatic), and biliary system obstruction (post-hepatic)
Laboratory considerations include hemolysis (increased indirect bilirubin), hepatocellular damage (elevated bilirubin, ALT and ALP), and biliary obstruction (elevated bilirubin and ALP)

Alkaline Phosphatase (ALP)

ALP is derived from liver, bone, intestine, and placenta
Increased ALP indicates increased synthesis by cells lining bile canaliculi, cholestasis, infiltrative liver diseases, or cirrhosis

Plasma Proteins

Albumin is produced by the liver with a biological half-life of around 20 days
Hypoalbuminemia is observed in advanced chronic liver disease and severe acute liver damage

Prothrombin Time (PT)

Prothrombin time measures the time it takes for blood to clot, reflecting hepatic synthesis function
Prothrombin is made by the liver and plays a role in the blood clotting cascade
Has a very short half-life (60 to 72 hours)
Normal PT indicates normal blood clotting protein. Increased PT indicates decreased synthesis

Gamma-Glutamyl Transpeptidase (GGT)

GGT is a very sensitive marker of liver pathology, associated with detoxification and alcohol ingestion, drugs like phenytoin, and conditions like cholestasis.
Commonly increased GGT accompanies raised ALT

Acute/Chronic Liver Disease

Acute liver disease has common causes like poisoning (paracetamol overdose, plant/fungal toxins), liver infection (hepatitis A, B, C), inadequate liver perfusion (blood loss), and others
It can resolve, or progress to acute hepatic failure (medical emergency, not compensated, renal failure), or lead to chronic hepatic damage.
Chronic liver disease includes alcoholic liver disease, chronic active hepatitis, primary biliary cirrhosis, and nonalcoholic fatty liver disease; it may progress to cirrhosis (late stage fibrosis of the liver)

Cirrhosis

Cirrhosis is the final stage of chronic liver damage characterized by scarring of the liver, decreased function, and irreversible changes.
Commonly associated with chronic conditions, particularly alcohol abuse (though reversible in the preceding stages)
It can lead to liver failure.
Diagnosis can be challenging and often features late diagnosis (common mistaken for fatigue, fibromyalgia, etc.)

Diagnosis of Cirrhosis and Liver Failure

Early cirrhosis (stable period) with years may have no biochemical indicators.
Late stages often showcase jaundice, encephalopathy, ascites, and bleeding.
Laboratory considerations include liver biopsy, antibody tests (hepatitis), copper/iron blood tests (Wilson/hemochromatosis diseases), albumin, PT, imaging.

Gilbert Syndrome

Genetic, autosomal recessive liver disease usually causing hereditary hyperbilirubinemia
Reduced activity of glucuronyl transferase, resulting in less conjugation of bilirubin, leading to high levels of unconjugated bilirubin.

Crigler-Najjar Syndrome

Rare genetic disorder, either autosomal recessive (Type I) or autosomal dominant (Type II), characterized by lack of glucuronyl transferase, resulting in severe unconjugated bilirubinemia, potentially life-threatening.

Dubin-Johnson Syndrome

Autosomal recessive genetic defect in the transportation of bilirubin from hepatocytes to bile
Signs include jaundice (early adolescence), upper abdominal pain, anorexia, nausea, and vomiting.
Dark pigmentation in the liver and increased serum bilirubin.

Hepatitis

Inflammation of the liver due to viruses, bacteria, toxins, chemicals, or alcohol.
Hepatitis can be acute (less than 6 months) or chronic (longer than 6 months)
Types A, B, C, D, and E are viral. Early symptoms include fatigue, jaundice, fever, nausea, tea-coloured urine, and clay-coloured feces.
Diagnosis panel may include testing for anti-HAV IgM, HBAg, anti-HBc IgM, anti-HCV.

Hepatitis A

Single-stranded RNA virus transmitted fecally
Greatest risk 2 weeks before symptoms. 70-80% jaundice.
Prevented by vaccination.

Hepatitis B

DNA virus transmitted through contact with blood, semen, and vaginal fluid.
Incubation (60-90 days) with potential for anorexia, vomiting, abdominal pain, dark urine, jaundice in 30-50% of cases. 15-25% develop chronic disease, requiring testing for hepatitis B core antigen and other antibodies.

Hepatitis C

Enveloped single-stranded RNA virus transmitted by blood transfusion or contaminated needles.
Incubation (2-26 weeks); 60-70% asymptomatic.
Symptoms include anorexia, malaise, fatigue, abdominal pain, and jaundice.
Higher risk of chronic cases compared to types A & B, and potentially cancers.

Laboratory Diagnosis of Viral Hepatitis

Non-specific tests (bilirubin, liver enzymes) and specific tests (antibodies to individual viral antigens, antigens of hepatitis B, etc.) aid in identifying type, acute/chronic, and past infection.

Hereditary Hemochromatosis

Autosomal recessive genetic disease characterized by iron overload/accumulation, potentially asymptomatic in the early stages.
Common cause is increased iron absorption, and 75% of impacted individuals are asymptomatic.
Early symptoms may include fatigue, impotence, and arthralgia, and later can result in organ damage, diabetes, skin hyperpigmentation, arthropathy, etc.

Diagnosis of Hereditary Hemochromatosis

Clinical evaluation might mistake symptoms for other conditions (fatigue, fibromyalgia, depression).
Blood tests are essential for diagnosis (serum iron, ferritin, transferrin saturation, liver function tests, total protein, albumin, glucose levels.)
Genetic testing can confirm the diagnosis.

Wilson Disease

An autosomal recessive disorder of copper metabolism impacting the liver, brain, eyes, heart, etc.
Copper absorption in the intestine but is not processed nor excreted properly resulting in copper buildup.
Signs include Kayser-Fleischer rings and liver, brain, kidney issues, and hepatic disturbances.
Laboratory features can show low serum copper but high urine copper, and low ceruloplasmin. Elevated AST, ALT, GGT, and bilirubin are also indicators.

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Description

Test your knowledge on the various functions of the liver and its associated disorders with this quiz. It covers topics such as ammonia conversion, hepatic portal vein function, and genetic inheritance patterns related to liver conditions. Perfect for medical students or anyone interested in hepatology.