Approach to jaundice

Question 1

How can we best define the clinical sign of jaundice?

Answer 1

hyperbilirubinaemia causing yellowing of body tissues

Question 2

What are the 3 categories of jaundice?

Answer 2

• pre hepatic: Relates to increased haemoglobin destruction
• hepatic: The liver doesn’t do it’s job and reduced conjugation of bilirubin
• post hepatic: The conjugated bilirubin cannot exit via the biliary system

Question 3

What is the most likely cause of pre-hepatic jaundice?

Answer 3

IMHA

Question 4

How can we tell if jaundice is pre-hepatic?

Answer 4

Haematology
- Anaemia: regenerative; macrocytic, hypochromic
- Blood Smear: Spherocytosis, Auto-agglutination

Imaging
(primarily looking for neoplastic causes of IMHA)
- 3 view CXR, Lung and abdominal ultrasound.
- Advanced imaging – CT with contrast

Serum and urine discolouration
- Haemoglobinaemia
- Haemoglobinuria

Further bloods/infectious disease screening

Toxin/ drug risk

Other clues eg pyrexia, pallor, haemic murmur

Question 5

What are the most likley causes of hepatic jaundice?

Answer 5

Infectious (hepatitis)
* Bacterial
* Fungal
* Viral
* CAV, FIV, FIP, FeLV

Inflammatory
- Cholangiohepatitis

Neoplasia
- Lymphoma; MCT; adenocarcinoma

Drugs/Toxins
- Paracetamol
- NSAIDs ….and LOTS MORE!!!

Degenerative
- Amyloidosis
- Lipidosis (cats)
- Cirrhosis

Proximal biliary disease
- Cholangitis/ cholangiohepatitis

Question 6

What liver enzymes should we look for on bloods? What do they mean?

Answer 6

• ALT - part of pyruvate cycle, serum elevations consitent with hepatocellular damage
• AST - found in liver and muscle, often leveated in venepuncture
• ALP - concentrated amounts in biliary tree, small elevations in cats are significant
• GGT - helps determine biliary tract disease in combination with other enzymes

Question 7

From what point are liver function tests helpful?

Answer 7

Once 70% of the liver is lost - this is due to large functional reserve

Question 8

What liver function tests are available? What result do we expect with disease?

Answer 8

• bile acid stimulation test - prolonged
• clotting factors - down
• albumin - low values may support liver disease
• urea - low values support reduced liver function
• ammonia - high

Question 9

How can we tell if jaundice is hepatic?

Answer 9

• liver function tests
• biochemistry
• haematology
• imaging
  
  • Ultrasonography
  • CT/ contrast CT
  • Radiographs only indicate hepatic size
• liver sampling
  
  • FNA
  • biopsy
  • histophathology
  • culture and sensitivity

Question 10

What is most likely to cause post-hepatic jaundice?

Answer 10

extrahepatic bile duct obstruction (EHBDO)

Question 11

What are the 3 different types of EHBDOs? What are example causes for each?

Answer 11

Intraluminal obstruction
* Cholelithiasis (stones)
* Gall Bladder Mucocoele (Border Terriers)
* Inspissated Bile
* Gall bladder polyps
* Cysts (Cats)

Extramural
* Pancreatic disease
* Pancreatitis
* Pancreatic neoplasia
* Duodenal disease
* Infectious
* Inflammatory
* Neoplastic
* Porta hepatis stricture

Mural
* Inflammatory swelling
* Cholangitis,
* cholecystitis,
* choledochitis
* Neoplasia

Question 12

How can we tell if jaundice is post hepatic?

Answer 12

• liver function tests - largely normal
• pancreatic screening tests
• biliary tree sampling
  
  • FNA
  • biopsy of the gall bladder/mass
  • histopath
  • pancreas
  • culture and sensitivity
• biochemistry
  
  • In post-hepatic disease, ALP and GGT are often raised disproportionally compared to ALT
• imaging
  
  • ultrasound
  • CT/contrast CT
• haematology