Jaundice Flashcards
What is it?
Increased circulating bilirubin
Caused by altered metabolism of bilirubin
What is the 3 step pathway of bilirubin metabolism?
Pre-hepatic
Hepatic
Post-hepatic
What happens in the pre-hepatic stage?
Breakdown of haemoglobin in spleen to form harm and globing
Haem converted to bilirubin
Release of bilirubin into circulation
What happens in the hepatic stage?
Uptake of bilirubin by hepatocytes
Conjugation of bilirubin in hepatocytes
Excretion of conjugated bilirubin into biliary system
What happens in the post-hepatic stage?
Transport of conjugated bilirubin in biliary system
Breakdown of bilirubin conjugate in intestine
Re-absorption of bilirubin (entero-hepatic circulation of bilirubin)
When bilirubin is reabsorbed where does it go?
If it is not reabsorbed bilirubin is excreted in faeces
If reabsorbed, it is excreted in the urine or it goes back to the liver and is put into bile again
How is jaundice classified?
Pre-hepatic
Hepatic
Post-hepatic
What is the causes of pre-hepatic jaundice?
Increased release of haemoglobin from red cells (haemolysis)
This therefore causes an increased quantity of bilirubin
What are the hepatic causes of jaundice?
Cholestasis
Intra-hepatic bile duct obstruction
What are the 3 things that can go wrong in the hepatic stage?
Defective uptake of bilirubin
Defective conjugation
Defective excretion
What is cholestasis?
Accumulation of bile within hepatocytes or bile canaliculi (go onto form intrahepatic bile ducts)
What causes cholestasis?
Viral hepatitis
Alcoholic hepatitis
Liver failure
Drugs: therapeutic, recreational
Drug-induced cholestasis may be predictable or unpredictable. What does this mean?
Predictable: dose related
Unpredictable: not dose related
What causes an intrahepatic bile duct obstruction?
Primary biliary cholangitis
Primary sclerosing cholangitis
Tumours of the liver
What are some tumours that can arise in the liver?
Hepatocellular carcinoma
Tumours of intra-hepatic bile ducts
Metastatic tumours
What do both primary biliary cholangitis and primary sclerosing cholangitis progress to?
Cirrhosis
What is hepatic cirrhosis?
End stage chronic liver disease: response of liver to chronic injury
What are some causes of cirrhosis?
Alcohol
Hepatitis B, C
Immune mediated liver disease: auto-immune hepatitis, primary biliary cholangitis
Obesity: diabetes mellitus
Metabolic disorders: excess iron (primary haemochromatosis), excess copper (Wilson’s disease)
What are some complications of cirrhosis?
Altered liver function: liver failure
Abnormal blood flow: portal hypertension
Increased risk of hepatocellular carcinoma
What is hepatocellular carcinoma?
Malignant tumour of hepatocytes
What is cholangiocarcinoma?
Malignant tumour of bile duct epithelium
Are metastatic tumours common in the liver?
The liver is a common site of metastasis
What are some causes of hepatocellular jaundice?
Hepatocellular liver damage: drugs
Hepatitis: viral, alcohol, non-alcoholic steatohepatitis
Cirrhosis
What are some causes of post hepatic jaundice?
Structural disorder of the bile ducts Cholelithiasis Pancreatic cancer Pancreatitis Congenital atresia of bile duct Bile duct obstruction: cholangiocarcinoma/stricture Primary sclerosing cholangitis
What is cholelithiasis?
Gallstones
What are the risk factors for gallstones?
Obesity
Diabetes
What are the diseases of the gallbladder that can cause post-hepatic jaundice?
Inflammation of the gallbladder:
Acute cholecystitis
Chronic cholecystitis
What are the complications of acute cholecystitis?
Empyema
Perforation of gallbladder: biliary peritonitis
Progression to chronic inflammation
What are the complications of chronic cholecystitis?
Chronic inflammation and fibrosis of gallbladder
What are some causes of common bile duct obstruction?
Gallstones
Bile duct tumours
Benign stricture
External compression: tumours
What are the effects of common bile duct obstruction?
Jaundice
No bile excreted into duodenum
Infection of bile proximal to obstruction: ascending cholangitis
Secondary biliary cirrhosis if obstruction prolonged
What does jaundice look like?
Yellow discolouration of mucous membranes, sclera and skin
Scratch marks from itching (pruritus)
What is the urine and stool colour in each of the 3 types of jaundice?
Prehepatic: normal urine and stools
Hepatic: dark urine and slightly pale stools
Post hepatic: darkest urine and pale stools
What type of hyperbilirubinaemia is each of the 3 types of jaundice?
Prehepatic: unconjugated
Hepatic: mixed (unconjugated and conjugated)
Post hepatic: conjugated
Why does hepatic and post hepatic cause dark urine?
Conjugated bilirubin can be excreted via the urine (as it is water soluble), whereas unconjugated cannot
What are some clues on history of prehepatic, hepatic and posthepatic jaundice?
Prehepatic: history of anaemia (fatigue, dyspnoea, chest pain)
Hepatic: risk factors for liver disease (IVDU, alcohol), decompensation (ascites, variceal bleed, encephalopathy)
Post hepatic: abdominal pain
What are some clues on examination of prehepatic, hepatic and posthepatic jaundice?
Prehepatic: pallor, splenomegaly
Hepatic: signs of CLD
Post hepatic: palpable gall bladder
When is jaundice detectable?
Detectable when total plasma bilirubin levels exceed 34 umol/L (normal is up to 20)
What is the differential diagnosis of jaundice?
Carotenemia: caused by lots of carrots/beta carotene
What are the investigations into the cause of the jaundice?
Liver screen: hepatitis B + C serology, autoantibody profile and serum immunoglobulins Ultrasound abdomen: most important test, differentiates extrahepatic and intrahepatic obstruction CT MRI ERCP MRCP PTC EUS
How is jaundice treated?
Treat the underlying cause
