LFTs

Question 1

Pattern:

ALT/AST in 1000s, ALP mildly raised

Answer 1

Acute hepatitic picture

Question 2

Pattern:

AST/ALT in 100s

Answer 2

Chronic hepatitic picture

Question 3

Pattern:

ALP significantly raised, ALT/AST mildly raised, raised bilirubin

Answer 3

Cholestatic (obstructive) picture

Question 4

Pattern:

Raised gammaGT, increased mean corpuscular volume, AST/ALT mildly elevated (AST>ALT)

Answer 4

Alcoholic picture

Question 5

Pattern:

Raised gammaGT, increased mean corpuscular volume, AST/ALT mildly elevated (AST>ALT), raised bilirubin

Answer 5

Acute alcoholic hepatitis

Question 6

Pattern:

Liver enzymes may be normal, reduced albumin, raised coagulation tests

Answer 6

Cirrhosis/chronic liver disease

Question 7

ALT sources

Answer 7

Specific to liver

Question 8

AST sources

Answer 8

• Liver
• Heart
• Skeletal muscle
• Kidneys
• Pancreas

Question 9

What would cause a marked increase (>1000) in ALT and AST?

Answer 9

1. Toxin/drug induced hepatitis eg paracetamol
2. Acute viral hepatitis (Hope A/B/E, EBV, CMV)
3. Liver ischaemia

Question 10

What would cause a modest increase (300-500) in ALT and AST?

Answer 10

• Chronic viral/alcoholic/autoimmune hepatitis
• Biliary obstruction

Question 11

What would cause a mild increase (<300) in ALT and AST?

Answer 11

• Cirrhosis
• Non-alcoholic fatty liver disease
• Hepatocellular carcinoma
• Haemachromatosis/Wilson’s disease

Question 12

ALP sources

Answer 12

Main sources:

biliary ducts, bone (Paget’s disease, bony metastasis, fractures, osteomalacia, renal bone disease)

Lesser sources:

placenta, small intestine (fatty meals), kidneys (chronic kidney disease)

Question 13

How can you determine if ALP is of hepatic origin?

Answer 13

GammaGT mirrors ALP so can be used to determine if ALP is of hepatic origin.

Question 14

What would cause a marked increase (>4x normal) in ALP?

Answer 14

Cholestasis (eg gallstones, primary biliary cholangitis, primary sclerosing cholangitis, pancreatic cancer, drugs)

Question 15

What would cause gammaGT to be raised?

Answer 15

• Alcohol abuse
• Enzyme inducing drugs

Question 16

What would cause an increase in unconjugated bilirubin?

Answer 16

• Increased red blood cell break down
• Impaired hepatic uptake (drugs, heart failure)
• Imparied coagulation (Gilbert’s syndrome, physiological neonatal jaundice)

Question 17

Causes of increased conjugated bilirubin

Answer 17

• Hepatocellular dysfunction (liver disease)
• Impaired hepatic secretion (cholestasis)

Question 18

Functional liver tests

Answer 18

• Albumin (albumin is synthesised in the liver and has a half life of around 20 days)
• Prothromin time / INR (depends on clotting factors and fibrinogen which are synthesised by the liver)

Question 19

What would cause a raised PT / INR?

Answer 19

• Liver disease (with imparied function)
• Vitamin K deficiency
• Consumptive coagulopathy (eg disseminated intravascular coagulation)

Question 20

What could macrocytic anaemia in the context of deranged LFTs indicate?

Answer 20

Alcohol

Question 21

What could thrombocytopenia in the context of deranged LFTs indicate?

Answer 21

Effect of alcohol on bone marrow, hypersplenism, liver cirrhosis, or disseminated intravascular coagulation

Question 22

Further investigations to find cause of deranged LFTs

Answer 22

• Viral
  
  • Viral hepatides: hepatitis A IgM, hepatitis B surface antigen, hepatitis C IgG, hepatitis E IgM
  • CMV serology
  • EBV serology
• Autoimmune liver screen
  
  • Anti-smooth muscle (autoimmune hepatitis type 1)
  • Anti-mitochondrial (primary biliary cholangitis)
  • Anti-nuclear (autoimmune hepatitis type 1, SLE)
• Tumour markers - if cirrhosis/weight loss
  
  • alpha-fetoprotein (hepatocellular carcinoma)
• Infiltrative
  
  • Ferritin and transferrin saturation (haemachromatosis)
  • Serum copper and caeruloplasmin + 24 hour urinary copper
  • Fasting glucose and lipids (fatty liver disease)
• Metabolic
  
  • alpha1-antitrypsin
  • Immunoglobulins and protein electrophoresis (IgM raised in primary biliary cholangitis, IgA raised in alcoholic liver disease, IgG raised in autoimmune hepatitis)
  • TTG antibody (Coeliac disease)
• Toxins
  
  • Paracetamol level (paracetamol overdose)

Question 23

Non-hepatic causes of deranged LFTs

Answer 23

• Drugs:
  
  • Hepatitis: sodium valproate, methotrexate, paracetamol, tuberculosis antibiotics
  • Cholestasis: co-amoxiclav, clarithromycin, carbamazepine, chlorpromazine
• Right heart failure
• Sepsis
• Coeliac disease
• Haemolysis
• Hyperthyroidism
• Right lower lobe pneumonia