HPB Flashcards
What is jaundice?
= yellow discoloration of the sclera, skin and mucous membranes secondary to hyperbilirubinaemia.
What is the normal range of bilirubin and at what value is jaundice typically clinically visible?
normal varies, but is typically from 3 – 21 mmol/L.
Generally the bilirubin needs to be around twice the upper limit (~40-50+) to be clinically visible.
what is the cause of pruritus in jaundice?
generally due to excess bile salts in the skin rather than the bilirubin itself
Physiology of bilirubin in the body
- Bilirubin is a product of haemoglobin breakdown. When a red cell is broken down (typically in the spleen), this releases unconjugated bilirubin (UCB).
- UCB is fat soluble and binds to albumin before being transported to the hepatocytes of the liver.
- In the liver it is conjugated by a hepatic enzyme. This conjugated bilirubin (CB) is then stored in the gallbladder as part of bile.
- Bile is released during digestion, where the CB is then broken down in the small intestine into Urobilinogen.
- Urobilinogen then takes 1 of 3 paths:
=> Converted to stercobilin in the gut and excreted in the stool
=> Absorbed into blood before being excreted by the kidney in the urine.
=> Recycled back to the liver to be re-excreted in bile.
What are the 3 categories of causes of jaundice?
- Pre-hepatic
- Hepatic
- Post-hepatic
What occurs in pre-hepatic jaundice?
Increased breakdown of RBCs leads to increased UCB – this overwhelms the capacity of the hepatocytes to conjugate it
=> There will be leftover UCB in the bloodstream and results in jaundice
Causes of pre-hepatic jaundice
Severe Malaria
Pernicious anaemia
Sickle cell disease (these may die faster than normal RBCs)
Thalassaemia
Transfusion reactions
Autoimmune haemolytic anaemias
Gilbert’s Syndrome
Gilbert’s Syndrome
= an autosomal recessive inherited condition – defective gene encoding for the hepatic conjugation enzyme.
Intermittent jaundice in the absence of haemolysis or underlying liver disease.
Will see isolated elevated UCB on investigation
Benign and self-limiting condition
What occurs in hepatic/hepatocellular Jaundice?
Can be either:
- UCB not conjugated at a sufficient rate, leading to increased circulating UCB.
- A degree of obstruction means that CB not being transported into biliary ducts, CB builds up in the hepatocytes and ends up in the bloodstream (increased circulating CB).
Causes of hepatic jaundice?
Viral hepatitis
Alcoholic hepatitis/cirrhosis
Drug-induced liver injury
- Paracetamol overdose
- Iatrogenic – e.g. flucloxacillin, co-amoxiclav, anti-epileptics
Autoimmune hepatitis
Wilson’s disease
Wilson’s disease
very rare autosomal recessive disorder of copper metabolism.
Can result in excess deposition of copper in tissues.
Clinical sign – Kayser Fleischer rings
What occurs in post-hepatic/Obstructive jaundice?
Blockage of the biliary tree obstructs drainage and causes bile (containing CB) to back up into the liver.
Pressure backs up bile between hepatocytes back to vasculature and CB is pushed back into the bloodstream (conjugated hyperbilirubinaemia).
Causes of post-hepatic/Obstructive jaundice
Gallstones in common bile duct.
Cholangiocarcinoma
Strictures
Pancreatic cancer
Primary sclerosing cholangitis
Primary biliary sclerosis
Abdominal masses
Drug-induced cholestasis
Pre-hepatic jaundice - urine and stool colour
Urine will be normal
Stools will be normal
Hepatic jaundice - urine and stool colour
Urine will be dark
Stool may be slightly pale
Post-hepatic jaundice - urine and stool colour
Urine will be dark
Stool will be pale
What causes dark urine in jaundice?
Excess of conjugated bilirubin, which can be excreted in the urine
(Unconjugated cannot be excreted in the urine)
What causes pale stools in jaundice?
Pale stools occur if conjugated bilirubin cannot be converted to stercobilin in the gut (i.e. if there is an obstruction preventing bile from reaching the intestine)
What is Charcot’s Triad?
What typically causes this?
= jaundice, fever (usually with rigors), and RUQ pain
Indicates an ascending cholangitis
DDx for jaundice with abdominal pain?
Pancreatitis, gallstones, ascending cholangitis
Sickle cell, drug-induced hepatitis, alcoholic hepatitis, viral hepatitis, cholangiocarcinoma, pancreatic cancer.
Haemolytic jaundices are classically painless, apart from sickle cell crisis.
DDx for jaundice with fever?
Malaria (periodic fever; every third day) Viral hepatitis Cholangiocarcinoma Pancreatitis Ascending cholangitis
(Gallstones (only if infected))
DDx for jaundice with weight loss?
Severe malaria, pernicious anaemia – loss of appetite.
Cholangiocarcinoma, pancreatic cancer
DDx for jaundice and ETOH excess?
Alcoholic hepatitis – generally misuse over a long period of time, but also sometimes binge-drinking.
Pancreatitis
DDx for jaundice and exotic travel?
Severe malaria
Viral hepatitis