Obstructive Jaundice Flashcards
How is bile produced?
haem catabolism
uridine diphosphate glucuronyltransferase conjugates bilirubin –> bilirubin glucuronide –> secreted into bile
hepatocytes generate primary bile in canaliculi
= conjugated bilirubin + bile salts + cholesterol + phospholipids + proteins + ions + water
cholangiocytes modify canaliculi bile –> dilute and alkalinise bile
What does bile consist of?
water Na+, K+, Ca2+ HCO3- (slightly higher than plasma) Cl- (slightly lower than plasma) lipids
How is bile excreted?
cholecystokinin stimulates the gallbladder and common bile duct to contract
secretin stimulates biliary duct cells to secrete bicarbonate + water –> increase bile volume –> increases flow into the intestine
~620mL/day - lowest during fasting
95% of bile salts will be reabsorbed
How is haem made into conjugated bilirubin?
haem – (haem oxygenase) –> biliverdin – (biliverdin reductase) –> bilirubin –> glucaronic acid attached by uridine diphosphate glucoronyltransferase (UGT) –> urobilinogen
to be excreted via feaces and urine
unconjugated bilirubin is attached to albumin
detached when it meets the sinusoidal surface of the liver
diffuses through hepatocytes to be conjugated
What are the main types of jaundice? Give examples.
Haemolytic - drugs, inherited disorder eg SCD
Hepatic - cirrhosis, hepatitis
Obstructive/Cholestatic - CBD stones, pancreatic cancer
What are some RFs for jaundice?
excess alcohol use IV drug use occupational history travel history sexual activity pregnancy
How can you tell the difference between pre/hepatic and obstructive jaundice?
pre/hepatic - dark urine, slightly pale stool, v raised ALT, raised ALP, AST, splenomegaly
obstructive - dark urine, pale stool, v raised ALP, AST, raised ALT, no splenomegaly
What blood tests can be performed to determine the cause of jaundice?
LFTs Bilirubin PT + INR FBC Aminotransferase IgG4 Viral hepatitis serology Copper concentration
