Liver Function Tests

Question 1

Enzymes analysed (3)

Answer 1

Serum Transaminases (ALT/AST)
Alkaline Phosphatase  (ALP)
Gamma Glutamyl Transpeptidase (GGT)

Question 2

Indices of intrinsic synthetic function (3)

Answer 2

Albumin
Prothrombin Time/INR
Bilirubin - Context for disease

Question 3

Transaminases (2)

Answer 3

Intracellular but released from hepatocytes upon injury

Catalyses gamma-amino group transfers

Question 4

Alanine aminotransferase (ALT) (4)

Answer 4

Most common
More sensitive than AST
Predominantly cytosol-located and Liver
Short half-life of 47 hours

Question 5

Aspartate aminotransferase (AST) (3)

Answer 5

In cytosol and mitochondria
Present in Liver, Heart, Pancreas, Skeletal muscle, Brain, Lungs, RBCs, WBCs
Half Life of 17 hours

Question 6

Aminotransferases (7)

Answer 6

Often become deranged in all aetiologies
Marked increase in hepatocellular pathologies
Levels may/may not reflect extent of damage
Do not correlate with outcomes
Usually less than 500 U/L in obstructive jaundice
Except acute phase of biliary obstruction with passage of stone into CBD. This process may coincide with ALT values >1-2,000 U/L
This is often a very transient phenomenon and indices revert back to that of more cholestatic picture

Question 7

Alkaline Phosphatase (3)

Answer 7

Catalyses hydrolysis of organic phosphate esters
Half life of 1 week
Originates in biliary, bone placenta, intestine, kidney

Question 8

Gamma Glutamyl Transpeptidase (GGT) (6)

Answer 8

Involved in gluthionine metabolism, transfer of amino acids across cellular membranes and leukotriene metabolism
Present in cell membrane of liver, kidneys, bile duct, pancreas, gallbladder, spleen, heart, brain, and seminal vesicle - Not bone
Used as a diagnostic marker for liver or cholestatic diseases
Useful in determining whether elevated ALP is of bone or liver origin
GGT is “inducible”- Drugs particularly anticonvulsants and TCAs and Paracetamol. Diabetes mellitus, pancreatic disease, COPD, renal disease
Levels can be increased alcohol consumption

Question 9

Bilirubin

Answer 9

Breakdown product of haem
Uptake into the hepatocytes
Undergoes conjugation
Excreted via urine/faeces

Question 10

Isolated Hyperbilirubinaemia (2)

Answer 10

When LFTs are normal except elevated bilirubin

Classed in conjugated or unconjugated

Question 11

Prothrombin time (2)

Answer 11

Measure conversion time from Prothrombin to Thrombin
Increased levels indicate reduced synthetic functionality, drugs (Warfarin), Bile malabsorption (Vitamin K deficiency), consumptive coagulopathies, congenital coagulopathy

Question 12

History taking main points (7)

Answer 12

Use of any chemical or medication
Accompanying symptoms - Pruritus, jaundice, arthralgia, weight loss, exanthema, fever, anorexia
Parenteral exposures - IV medications/blood transfusions, intranasal drugs, tattoos and sexual history
Travel history including timings and exposure risks (contact with exotic zoonosis)
Alcohol exposure - Duration, units consumed
Occupational exposures
Temporal variation

Question 13

Medications (2)

Answer 13

LOOK AT TIMINGS - What has changed
Watch for Antibiotics, antidepressants, statins, Sulfonamides, NSAIDs, anti-epileptics, anti-TB medications, OTC medication

Question 14

ALT > ALP and increased or normal bilirubin indicates

Answer 14

Hepatocellular injury

Question 15

ALP > ALT with increased bilirubin indicates

Answer 15

Cholestasis

Question 16

Increased INR indicates (3)

Answer 16

Prolonged Jaundice
Vitamin K Malabsorption
Hepatocellular Dysfunction

Question 17

Acute hepatocellular injury picture (5)

Answer 17

Use AST:ALT ratio - Normal is 0.8, >2 suggests alcohol
Need liver screen from hepatitis, HIV, EBV, HSV (For pregnant or immunocomprimised)
Carry out doppler ultrasound
Review medication
Presence of hypotension episodes

Question 18

Mimic or overlapping conditions to acute hepatocellular injury (6)

Answer 18

Coeliac Disease
Muscle disorders (Myositis, Rhabdomyolysis)
Creatine Kinase (CK)
Adrenal Insufficiency
Anorexia Nervosa
Thyroid Disorders

Question 19

Rare causes for Acute hepatocellular injury (4)

Answer 19

Autoimmune hepatitis
Wilsons disease
Haemochromatosis
α1 Anti-trypsin deficiency

Question 20

Unconjugated Hyperbilirubinaemia causes (3)

Answer 20

Increased bilirubin production - Haemolysis, extravasation of blood into tissues
Impaired hepatic bilirubin uptake - Heart failure, portosystemic shunts, Drugs
Impaired bilirubin conjugation -
Hyperthyroidism, Advanced Liver Disease

Question 21

Conjugated Hyperbilirubinaemia causes (3)

Answer 21

Extrahepatic Cholestasis (Biliary Obstruction) - Acute/Chronic pancreatitis, cholelithiasis, cholangiocarcinoma, head of pancreatic tumour
Intrahepatic Cholectasis - Sepsis, cirrhosis, infiltrative diseases, acute hepatitis
Drugs - Alkylated steroids, Rifampicin

Question 22

Acute liver failure presentations (3)

Answer 22

Jaundice
Encephalopathy - Brain disease/damage
Coagulopathy - Bleeding disorder

Question 23

Maximum dose of paracetamol daily

Answer 23

4g

Question 24

What does smooth muscle antibody test indicate

Answer 24

Autoimmune disease

Question 25

Albumin test contraindication

Answer 25

Hard to use in isolation