Lab 4 Liver Investigations

Question 1

What are liver function tests (LFTs)?

Answer 1

A group of tests that reflect liver status

LFTs are used to differentiate between various liver conditions such as acute hepatocellular damage, cholestasis, and chronic liver disease.

Question 2

What does ALP stand for and what is its use?

Answer 2

Alkaline phosphatase; used to diagnose cholestasis

ALP is an enzyme that hydrolyzes phosphate esters and is elevated in cholestasis.

Question 3

What does ALT stand for and what is its significance?

Answer 3

Alanine aminotransferase; used to diagnose hepatocellular damage

ALT is a sensitive indicator of liver damage but not specific, as it can also be found in other tissues.

Question 4

What does AST stand for and what does it indicate?

Answer 4

Aspartate aminotransferase; used to diagnose hepatocellular damage

AST is another aminotransferase that indicates liver damage but is not liver-specific.

Question 5

What is the role of GGT?

Answer 5

Gamma-glutamyl transferase; used to diagnose cholestasis

GGT is elevated in conditions affecting bile flow.

Question 6

What does bilirubin measure in liver function tests?

Answer 6

Capacity of liver to detoxicate and excrete; also used to diagnose jaundice

Elevated bilirubin levels indicate impaired liver function.

Question 7

What is the purpose of measuring albumin in LFTs?

Answer 7

To measure synthetic capacity of the liver

Albumin levels can indicate liver function and overall health.

Question 8

What are aminotransferases and why are they important?

Answer 8

Enzymes like ALT and AST that produce non-essential amino acids; sensitive indicators of hepatocellular damage

Increased plasma activity can occur even with minor liver damage.

Question 9

True or False: ALT and AST are specific to liver damage.

Answer 9

False

ALT and AST can also be found in muscle, heart, and kidney.

Question 10

What does cholestasis refer to?

Answer 10

Obstruction of bile flow from the liver

Cholestasis can lead to elevated levels of ALP and GGT.

Question 11

What factors affect the reference ranges for alkaline phosphatase (ALP)?

Answer 11

Age and developmental stage; elevated in children and adolescents, decreased in elderly

These variations are due to factors like bone growth and resorption.

Question 12

Fill in the blank: ALT and AST are commonly measured _______.

Answer 12

aminotransferases

They are key indicators in liver function tests.

Question 13

What is Albumin a marker of?

Answer 13

Long term liver function

Albumin has a half-life of 20 days.

Question 14

What does Prothrombin time measure?

Answer 14

The rate of conversion of prothrombin to thrombin in the presence of coagulation factors

Clotting factors and vitamin K are synthesized by the liver.

Question 15

What does prolonged Prothrombin time indicate?

Answer 15

Liver dysfunction

Prothrombin time has a half-life of 6 hours.

Question 16

What is Jaundice?

Answer 16

Yellow discoloration of the skin and the sclera of the eyes due to hyperbilirubinemia

Not detectable until plasma bilirubin >50μmol/L.

Question 17

What causes pre-hepatic jaundice?

Answer 17

Increased bilirubin production (unconjugated)

Possible causes include haemolysis or decreased albumin levels.

Question 18

What causes hepatic jaundice?

Answer 18

Decreased bilirubin conjugation (unconjugated)

Possible causes include failure of bilirubin conjugation (Gilbert’s syndrome), hepatitis, malignancy, cirrhosis, or drug interaction.

Question 19

What causes post-hepatic jaundice?

Answer 19

Decreased bilirubin excretion (conjugated)

Possible causes include gallstones, malignancy, or pancreatitis.

Question 20

What confirms hyperbilirubinemia?

Answer 20

Total bilirubin

Bilirubin fractions help determine the cause of jaundice.

Question 21

What do the bilirubin fractions indicate?

Answer 21

Unconjugated → pre-hepatic or hepatic; conjugated → hepatic or post-hepatic

This helps in diagnosing the type of jaundice.

Question 22

What does AST/ALT suggest?

Answer 22

Hepatocellular damage

These are enzymes that indicate liver cell injury.

Question 23

What do ALP/GGT indicate?

Answer 23

Cholestasis (hepatic or post-hepatic)

These enzymes are used to assess bile duct obstruction or liver disease.

Question 24

What does low Albumin suggest?

Answer 24

Compromised synthesis (chronic damage)

Albumin levels can indicate the liver’s ability to produce proteins.

Question 25

What does prolonged PT suggest?

Answer 25

Compromised synthesis (acute damage) ## Footnote Prothrombin time reflects the liver's ability to produce clotting factors.

Question 26

What is Kernicterus?

Answer 26

Neonatal unconjugated hyperbilirubinemia brain damage ## Footnote Kernicterus occurs due to high levels of unconjugated bilirubin in neonates.

Question 27

What causes Kernicterus?

Answer 27

* Immature liver function * Bilirubin crosses the blood-brain barrier, making it neurotoxic ## Footnote These factors lead to the accumulation of bilirubin in the brain, resulting in damage.

Question 28

What bilirubin level indicates the need for phototherapy?

Answer 28

>200μmol/L ## Footnote Phototherapy helps convert bilirubin into a water-soluble form for easier excretion.

Question 29

What is the effect of blue light on bilirubin?

Answer 29

Converts bilirubin to a water-soluble form ## Footnote This conversion is crucial for reducing bilirubin levels in the body.

Question 30

What bilirubin level may require exchange transfusion?

Answer 30

>300μmol/L ## Footnote Exchange transfusion is a procedure to rapidly reduce high bilirubin levels.

Question 31

What is cholestasis?

Answer 31

A condition where bile cannot flow from the liver to the duodenum ## Footnote Cholestasis can lead to various symptoms and complications related to bile flow.

Question 32

What are the two types of cholestasis?

Answer 32

* Hepatocyte damage (intra-hepatic) * Obstruction of bile ducts (extra-hepatic) ## Footnote The type depends on whether the issue is within the liver or in the bile ducts.

Question 33

List some symptoms of cholestasis.

Answer 33

* Fatigue * Pruritus * Dark urine * Malabsorption of fat-soluble vitamins * Osteoporosis * Jaundice ## Footnote These symptoms arise from bile accumulation and its effects on the body.

Question 34

What causes pruritus in cholestasis?

Answer 34

Bile salts in the blood irritating PNS nerves ## Footnote This irritation leads to itching of the skin, a common symptom of cholestasis.

Question 35

How does cholestasis affect fat-soluble vitamins?

Answer 35

Causes malabsorption ## Footnote This can lead to deficiencies in vitamins A, D, E, and K.

Question 36

What is a late-stage symptom of cholestasis?

Answer 36

Jaundice ## Footnote Jaundice occurs due to the buildup of bilirubin in the body.

Question 37

What can malabsorption of vitamin D lead to in cholestasis?

Answer 37

Osteoporosis ## Footnote Vitamin D is essential for calcium absorption and bone health.

Question 38

What are gallstones?

Answer 38

Deposition of cholesterol or bilirubin in the gallbladder ## Footnote Gallstones are formed when there is an imbalance in the substances that make up bile.

Question 39

What is a common cause of post-hepatic cholestasis?

Answer 39

Gallstones ## Footnote Post-hepatic cholestasis occurs when bile flow is obstructed after it has left the liver.

Question 40

Which type of gallstones is more common?

Answer 40

Cholesterol stones ## Footnote Cholesterol stones account for the majority of gallstone cases.

Question 41

What percentage of adults have gallstones?

Answer 41

1 in 10 adults ## Footnote This equates to approximately 10% of the adult population.

Question 42

What proportion of individuals with gallstones develop symptoms?

Answer 42

Minority develop symptoms ## Footnote Most people with gallstones remain asymptomatic.

Question 43

About what fraction of individuals with gallstones will develop epigastric pain?

Answer 43

About 1/3 ## Footnote Epigastric pain is a common symptom associated with gallstones.

Question 44

What are two treatment options for gallstones?

Answer 44

* Endoscopic removal of stones * Cholecystectomy (remove gallbladder) ## Footnote Cholecystectomy is often performed when gallstones cause significant problems.

Question 45

What is a consequence of cholecystectomy?

Answer 45

Cannot concentrate bile ## Footnote This can lead to difficulties in fat absorption.

Question 46

What are potential effects of cholecystectomy on digestion?

Answer 46

* Affects fat absorption * Diarrhoea ## Footnote Without the gallbladder, bile is released continuously, affecting fat digestion.

Question 47

What is acute hepatitis?

Answer 47

Acute inflammation of the liver ## Footnote It can be caused by various factors including infections and metabolic disorders.

Question 48

List some causes of acute hepatitis.

Answer 48

* EBV * CMV * Wilson's disease * AAT deficiency * Viral hepatitis (A, B, C, D, E) ## Footnote These causes can lead to liver inflammation and damage.

Question 49

What is true about viral hepatitis?

Answer 49

Usually self-limiting (~80% undiagnosed) ## Footnote Many cases of viral hepatitis resolve without specific treatment.

Question 50

What are common symptoms of acute hepatitis?

Answer 50

Flu-like symptoms ## Footnote Symptoms may include fatigue, fever, and malaise.

Question 51

What defines acute liver failure?

Answer 51

Severe liver dysfunction with encephalopathy and coagulopathy ## Footnote It represents a critical condition requiring immediate medical attention.

Question 52

When can acute liver disease progress to acute liver failure?

Answer 52

When the rate of hepatocyte death exceeds the regenerative capacity of the liver ## Footnote This progression can occur due to various acute insults to the liver.

Question 53

What is the diagnostic criterion for acute liver failure regarding INR?

Answer 53

INR > 1.5 ## Footnote This indicates significant liver dysfunction affecting coagulation.

Question 54

What neurological condition is associated with acute liver failure?

Answer 54

Neurologic dysfunction with any degree of hepatic encephalopathy ## Footnote This can manifest as confusion, altered consciousness, or coma.

Question 55

What is a requirement for diagnosing acute liver failure regarding prior liver disease?

Answer 55

No prior evidence of liver disease ## Footnote This helps differentiate acute liver failure from chronic liver conditions.

Question 56

What is the disease course duration for acute liver failure?

Answer 56

< 26 weeks ## Footnote This timeframe is critical for the classification of the condition.

Question 57

What is cirrhosis?

Answer 57

Cirrhosis is a condition where normal liver tissue is replaced by fibrous (scar) tissue ## Footnote This condition results from prolonged damage to the liver.

Question 58

What happens to the liver's regeneration power in cirrhosis?

Answer 58

The regeneration power is lost due to prolonged damage to the liver ## Footnote This occurs when hepatocellular damage exceeds hepatocellular regeneration.

Question 59

What is the relationship between hepatocellular damage and regeneration in cirrhosis?

Answer 59

Hepatocellular damage is greater than hepatocellular regeneration ## Footnote This imbalance contributes to the progression of cirrhosis.

Question 60

What is a hallmark of cirrhosis?

Answer 60

Portal hypertension ## Footnote This condition is characterized by increased blood pressure in the portal venous system.

Question 61

What does bridging of fibrous tissue between portal triads indicate?

Answer 61

It indicates blood flow obstruction ## Footnote This is a significant feature of cirrhosis.

Question 62

What is the typical finding of total bilirubin in chronic liver disease?

Answer 62

Total bilirubin is elevated ## Footnote This elevation is a common laboratory finding in liver disease.

Question 63

Which bilirubin fraction is usually higher in chronic liver disease?

Answer 63

Unconjugated bilirubin is greater than conjugated bilirubin ## Footnote This pattern can help differentiate types of liver dysfunction.

Question 64

What is the typical AST/ALT pattern in chronic liver disease?

Answer 64

Marked elevation in both AST and ALT ## Footnote These enzymes are indicators of hepatocellular injury.

Question 65

What is observed in alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) levels in cholestatic conditions?

Answer 65

Elevation in ALP and GGT ## Footnote This indicates cholestasis, a condition where bile cannot flow from the liver to the duodenum.

Question 66

What is the typical albumin level in chronic liver disease?

Answer 66

Albumin is low ## Footnote This is due to decreased synthesis in the liver.

Question 67

What is the prothrombin time (PT) status in chronic liver disease?

Answer 67

PT is prolonged ## Footnote This occurs due to impaired synthesis of clotting factors in the liver.

Question 68

What are the applications of liver function tests (LFTs)?

Answer 68

Applications include: * Screening for liver disease * Diagnosing liver disease * Prognosis of liver disease * Monitoring progression of liver disease ## Footnote LFTs serve multiple purposes in assessing liver health and disease progression.

Question 69

What must occur before liver function is considered abnormal?

Answer 69

Liver damage must be severe before liver function is abnormal ## Footnote This highlights the resilience of liver function and the need for significant damage to detect abnormalities.

Question 70

What are functional assays in the context of liver function tests?

Answer 70

Functional assays include: * Clearance of metabolic products * Synthesis of proteins ## Footnote These assays help assess liver function indirectly.

Question 71

Why is the term 'liver function tests' considered a misnomer?

Answer 71

Very few tests actually measure liver function and it is time-consuming, dependent on hepatic blood flow, and has huge variability ## Footnote This indicates that LFTs may not provide a complete picture of liver health.