Robbins 9th ed - Chapter 18 - Cholecystitis + Cholelithiasis + Jaundice (1)

Question 1

What is bilirubin?

Answer 1

An end-product of haem breakdown.

Question 2

Name the 6 stages of haem breakdown.

Answer 2

1. Haem is released from aging RBCs
2. Haem converted to biliverdin
3. Biliverdin converted to bilirubin (water insoluble)
4. Bilirubin binds to albumin for transport to liver
5. Conjugation with glucoronic acid in the ER in the liver, into water-soluble conjugated bilirubin that is readily excreted into bile
6. Gut bacteria deconjugate it to urobilinogen, which is excreted in faeces + urine

Question 3

What are the major causes of conjugated hyperbilirubinaemia?

Answer 3

Extrahepatic biliary obstruction, by either calculi or carcinoma.

Question 4

What are the major causes of unconjugated hyperbilirubinaemia?

Answer 4

1. Haemolytic anaemia + Haemorrhage.
2. Newborn: immature conjugation and excretion systems. (also, breast milk contains glucuronidase which deconjugates bilirubin)
3. Diffuse hepatocellular disease: cirrhosis, hepatitis.

Question 5

What are some clinical features of cholestasis?

Answer 5

Jaundice
Pruritis
Xanthomas (visible accumulations of cholesterol)
Deficiencies of vitamins A, E, D, K (fat-soluble)

Question 6

In the developed world, what proportion of the population are afflicted by gall stones?

Answer 6

20%

Question 7

Name some risk factors and epidemiological features predisposing to gall stone formation.

Answer 7

Western culture.
Female (especially with increased oestrogen exposure in OCP or pregnancy).
Native American.
Increasing age.
Obesity.
Rapid weight loss.
FHx (various hereditary factors).

Question 8

What are the two types of gall stones? Which one is more common.

Answer 8

There are cholesterol stones (common) and pigment stones (much less common).

Question 9

Describe the factors that contribute to the pathogenesis of cholesterol stone formation.

Answer 9

1. Hypersecretion of cholesterol, which supersaturates the bile, and thus cholesterol can no longer be dispersed. It then nucleates into solid cholesterol monohydrate crystals.
2. Hypomotility of the gall bladder
3. Hypersecretion of mucus in the gall bladder, which traps the nucleated crystals.

Question 10

What are pigment stones made of?

Answer 10

Unconjugated bilirubin and calcium salts.

Question 11

What is the most common cause of cholecystitis? What proportion of cases are caused by this?

Answer 11

90% of cholecystitis is caused by a gall stone obstructing either the cystic neck or the cystic duct.

Question 12

Describe the pathogenesis of acute calculous cholecystitis.

Answer 12

A stone blocks the flow of bile, which causes chemical irritation to the gall bladder wall, causing inflammation. Bacterial infection eventually superimposes this underlying damage.

Question 13

What colour are pigment stones?

Answer 13

Brown or black.

Question 14

What colour are cholesterol stones?

Answer 14

Pale yellow / brown.