Investigation of Jaundice

Question 1

What is Jaundice?

Answer 1

= yellow appearance of skin, sclera & mucous membrane caused by excess Bilirubin in blood

Question 2

How does Bilirubin get transported from the Reticular Endothelial System (RES) to Liver? (3 steps)

shush

Answer 2

1. bc Unconjugated Bilirubin is insoluble in water so needs the transporter (Albumin)
2. Unconjugated Bilirubin taken up by Hepatocytes
3. Unconjugated bilirubin is conjugated with Glucaronic acid to form Conjugated Bilirubin

Question 3

How does Bilirubin get transported from the Liver to the Gut?

Answer 3

• Conjugated bilirubin is water soluble
• Most enters the Biliary system at the duodenum
• Of this, 95% is reabsorbed at the Ileum via Enterohepatic circulation back to the Liver
• Remaining 5% is hydrolysed by the flora & forms Urobilinogen (colourless) -> gets excreted

Question 4

What are 3 things that can happen to Urobilinogen?

Answer 4

1. get oxidised by gut bacteria Stercobilin -> gives stools brown colour
2. get reabsorbed and recycled by the liver
3. get reabsorbed and excreted in urine -> gives urine colourless appearance

Question 5

Why does Jaundice occur?

Answer 5

fault in Bilirubin sequence -> build up of Bilirubin in the blood

Question 6

Describe Unconjugated Bilirubinaemia

Answer 6

• there is a fault upstream of conjugation
• Causes:
  
  • Haemolysis -> faster than normal breakdown
  • Congenital defects in Liver’s uptake
• Biochemistry:
  
  • will be excess Urobilinogen in urine (no increase in
    Bilirubin in urine)

Question 7

Describe Conjugated Bilirubinaemia

Answer 7

• Fault/blockage downstream of conjugation
• Causes (Anything that causes obstruciton):
  
  • Gall Stones
  • Tumours
  • Multiple small blockages in Liver
  • Primary/Secondary Liver Tumours
• Biochemistry:
  
  • Conjugated Bili from liver cant reach the gut
  • Spills into bloodstream -> can make urine dark bc Conj. Bili
    is water soluble
  • Decreased Bili in gut -> little to no Urobilinogen -> Less
    Urobili in urine

Question 8

Describe Hepatocellular Jaundice? what type of bilirubinaemia can it cause?

Answer 8

• Damage to hepatocytes in LIver
• Early on, both types of Bilirubin contribute to Jaundice
• As it progresses -> Conj. Bilirubinaemia = dominant
• Causes:
  
  • Viral Hepatitis
  • Alcohol

Question 9

What are common things found in Jaundicen History (list 7)

Answer 9

• Recurring pain in upper quadrant -> Gallstones
• Weight Loss -> carcinoma at pancreas (blocks bile duct)
• Blood transfusions -> viral Hepatitis
• Rec. Drugs -> Hepatitis B & C
• Fam Hx -> e.g Haemochromatosis
• Travel Hx -> certain areas = risky
• Alc abuse

Question 10

What are 2 ways to investigate Jaundice?

Answer 10

• Urinalysis
• Liver function tests

Question 11

How can Urinalysis be used to investigate Jaundice?

Answer 11

• Presence of Urobilinogen:
  
  • Increased Urobili -> Prehepatic Jaundice
  • No Urobili -> Obstructive Jaundice bc Bilruibin cant
    progress past small intestine
• Presence of Bilirubin:
  
  • present in urine -> Obstructive jaundice (bc conj bili = h2o
    soluble)
  • absent in urine = Prehepatic jaundice (unconj = insoluble
    in h20)

Question 12

How can Liver Function Tests be used to investigate Jaundice?

Answer 12

• Alkaline Phosphatase (ALP) prod by epithelial cells ->
  increased levels in intrahepatic obstruction
• Gamma-glutamyl Transferase (GGT) prod by epithelial cells
  -> increased levels = intrahepatic obstruction