Liver Function Tests

Question 1

List the 4 main functions of the liver

Answer 1

Protein metabolism
CHO metabolism
Lipid metabolism
Detoxification and excretion

Question 2

What are the 8 LFTs commonly provided by labs in Aus?

Answer 2

Protein
Albumin
Bilirubin
ALT
AST
GGT
ALP
LD

Question 3

What are the 6 main liver proteins?

Answer 3

Albumin
a1-antitrypsin
a2-macroglobulin
Haptoglobin
B-lipoprotein
Transferrin

Question 4

Which liver enzymes are predominantly cytoplasmic?

Answer 4

ALT
AST
LD

Question 5

Which liver enzymes are nuclear?

Answer 5

DNA synthase

Question 6

Which liver enzymes are located on the membrane?

Answer 6

ALP

GGT

Question 7

Which liver enzymes are associated with organelles?

Answer 7

Mitochondrial AST

Lysosomal SOD

Question 8

What liver enzymes rise in liver necrosis?

Answer 8

ALT
AST
LD

Question 9

Which liver enzyme is particularly elevated in toxin-mediated liver necrosis? Why?

Answer 9

AST

Also damages organelles causing further release of AST

Question 10

Which liver enzymes rise in biliary disease?

Answer 10

ALP

GGT

Question 11

Give 2 examples of drugs which induce certain liver enzymes

Answer 11

Alcohol

Anticonvulsants

Question 12

Which liver enzymes are typically elevated with inducing drugs?

Answer 12

ALP

GGT

Question 13

What is the role of ALT?

Answer 13

Converts alanine to pyruvate which can then be converted to glucose (part of gluconeogenesis)

Question 14

What is the role of AST?

Answer 14

Important in Krebs cycle (involved in transporting oxaloacetate from the cytoplasm into the mitochondria)

Question 15

Is ALT or AST liver-specific?

Answer 15

ALT (L for liver-specific)

Question 16

Which has a longer half-life: AST or ALT? What are the clinical implications?

Answer 16

ALT (L for longer, S for shorter)
AST > ALT suggests acute process affecting mitochondria (e.g. toxins)
ALT > AST suggests chronic/resolving process (e.g. hepatitis)

Question 17

Which has the longest half-life: ALT, AST or GGT?

Answer 17

GGT (5-7 days)

Question 18

List 4 viruses (other than viral hepatitis) that can cause hepatitis

Answer 18

EBV
CMV
Q fever
Rubella

Question 19

Define a mild, moderate and severe ALT level

Answer 19

Mild: 250
Moderate: 1000
Severe: 5000

Question 20

What pattern of ALT is seen in chronic viral hepatitis?

Answer 20

Intermittent rises as virus tries to “break out” of liver to infect further

Question 21

What levels are generally seen in acute vs chronic hepatitis B/C?

Answer 21

Acute: can be around 5000
Chronic: 50-250

Question 22

List 6 medications/herbs that can cause liver damage

Answer 22

Flucloxacillin
Amoxicillin
Statins (atorva, simvi, prava, fluva)
Ethanol
Paracetamol
Herbal tea (kombucha)

Question 23

Where is ALP found?

Answer 23

Liver
Bone
Placenta

Question 24

Where is GGT found?

Answer 24

Liver
Biliary epithelium
Some renal

Question 25

What is GGT involved in?

Answer 25

Glutathione metabolic pathway (antioxidant pathway)

Question 26

What are the clinical features of extra- vs intra-hepatic cholestasis?

Answer 26

Extra: elevated conjugated bilirubin, markedly elevated GGT and ALP Intra: no jaundice, normal bilirubin, mildly elevated GGT and ALP

Question 27

What is a very poor sign in a pt with suspected cancer?

Answer 27

Very low albumin

Question 28

What is Gilbert's syndrome?

Answer 28

Mutation in promoter region of UDP glucuronosyltransferase (7 vs 6 normal repeats)

Question 29

What is bilirubin a predictor of? Describe the relationship. What is hypothesised to be the underlying reason for this relationship?

Answer 29

Cardiac disease The higher the bilirubin, the lower the risk of cardiac events Bilirubin is a physiological antioxidant which protects the myocardium and prevents LDL being oxidated

Question 30

What is the effect of fasting in a pt with Gilbert's disease?

Answer 30

Bilirubin rises as body is metabolically stressed

Question 31

What is the effect of weight on liver enzymes?

Answer 31

Increased ALT

Question 32

List 8 determinants of raised ALT

Answer 32

``` Younger men Ethnicity BMI WHR Serum leptin Serum triglycerides Serum insulin Plasma glucose ```

Question 33

What initial tests are recommended in suspected liver disease?

Answer 33

Serology Iron studies Glucose and lipids

Question 34

List 4 second line liver tests

Answer 34

HFE gene AutoAbs a1-antitrypsin assay Urine copper

Question 35

What are some of the drawbacks of LFTs?

Answer 35

Little prognostic value Little value for monitoring effect of therapy Do not assess liver "function" quantitatively or dynamically (more accurately liver damage tests)