Jaundice Flashcards
what are the three classifications of jaundice?
- pre-hepatic
- intrahepatic
- post-/extra-hepatic
what is pre-hepatic jaundice?
- occurs when bilirubin metabolism is affected before it reaches the liver, resulting in unconjugated hyperbilirubinemia
- it is typically caused by increased red cell haemolysis, which produces excess unconjugated bilirubin
how does haemolytic anaemia contribute to increased bilirubin levels?
- increases bilirubin due to increased haemolysis of red blood cells
- haemolysis can occur intravascularly or extravascularly (where phagocytes remove defective or antibody-coated red cells)
what are the genetic causes of haemolytic anaemia?
- red cell membrane defects (e.g. hereditary spherocytosis)
- haemoglobin abnormalities (e.g. sickle cell anaemia, thalassaemia)
- enzyme deficiencies (e.g. G6PD deficiency, pyruvate kinase deficiency)
what are the causes of acquired haemolytic anaemias?
acquired haemolytic anaemias are often immune-mediated and can be:
- isoimmune (e.g. blood transfusion reaction)
- autoimmune (e.g. SLE, lymphoma, leukaemia, drug-related)
what are non-immune causes of acquired haemolytic anaemia?
- disseminated intravascular coagulation (DIC)
- haemolytic uraemic syndrome (HUS)
- thrombotic thrombocytopenia
- hypersplenism
- cirrhosis
what is gilbert’s syndrome?
a benign genetic condition where bilirubin is not transported into bile at the usual rate, causing intermittent jaundice due to unconjugated hyperbilirubinaemia
what is crigler-najjar syndrome?
- a rare autosomal recessive disorder where deficiency of diphosphate glucuronosyltransferase impairs bilirubin conjugation and excretion, leading to unconjugated hyperbilirubinaemia
- it typically presents in neonates
what is intrahepatic jaundice?
occurs when hepatocyte damage reduces bilirubin conjugation or causes cholestasis
what are the three clinical phases of viral hepatitis?
- prodromal
- icteric
- convalescent
what is alcoholic hepatitis?
- occurs when the liver metabolises alcohol, producing acetaldehyde as a by-product
- this binds to proteins in liver cells, causing hepatocyte injury
what is decompensated cirrhosis?
- irreversible scarring of the liver with abnormal nodules
- symptoms of liver failure only become apparent when 80-90% of hepatic tissue is damaged
- it causes portal hypertension due to distortion of intrahepatic vasculature by fibrosis
what can trigger decompensation in a patient with cirrhosis?
- infection (e.g. SBP)
- bleeding (e.g. variceal bleeding)
- alcohol binge
what is primary biliary cholangitis (PBC)?
- a slowly progressive autoimmune disease that destroys small interlobular bile ducts, causing intrahepatic cholestasis
- this leads to hepatocyte damage, and fibrosis + can eventually progress to cirrhosis
what causes extra-hepatic jaundice?
occurs due to extra-hepatic cholestasis, often caused by:
- intraluminal structural abnormalities (e.g. strictures)
- extrinsic compression (e.g. tumours or gallstones)
how can malignancies cause bile duct obstruction?
- intraluminal obstruction (e.g. inside the common bile duct or gallbladder)
- extrinsic compression (e.g. pancreatic cancer)
what are the key features of cholangiocarcinoma in relation to jaundice?
- cancer of the gallbladder or bile duct that causes intraluminal obstruction of bile flow
- it often presents late with jaundice, RUQ pain + weight loss
What are the key features of pancreatic cancer in relation to jaundice?
- cancer of the head of the pancreas can cause extrinsic compression of the biliary tree, blocking bile flow
- it typically presents late with jaundice, weight loss + abdominal pain
how can pancreatitis cause jaundice?
- pancreatitis is inflammation of the pancreas, which presents with severe epigastric pain + vomiting
- jaundice can occur due to a common bile duct stone, excess alcohol use, or extrinsic compression of the common bile duct from pancreatic inflammation and swelling
what blood tests are used to investigate suspected pre-hepatic jaundice or haemolytic anaemia?
- haptoglobin (e.g. binds free Hb): ↓ in haemolytic anaemia
- lactate dehydrogenase (LDH): ↑ due to increased haemolysis
- blood film: identifies red cell abnormalities or haematological malignancy
- split bilirubin test: measures conjugated/unconjugated bilirubin — ↑ unconjugated bilirubin indicates pre-hepatic jaundice
what do LFTs show in hepatocellular jaundice?
- ↑ AST & ALT
- AST:ALT > 2:1 - ArLD
- ↑ GGT - EtOH
how is ascitic fluid analysed?
ascitic fluid is collected by ascitic aspiration + sent for:
- M, C & S
- gram staining is used to identify any organisms initially + count numbers of white cells
what does a raised white cell count in ascitic fluid indicate?
> 250/µL ( ↑ polymorphic) - SBP
250/µL ( ↑ lymphocytic) - TB
how is alcohol cessation supported in patients with liver disease?
- benzodiazepines (e.g. lorazepam, chlordiazepoxide)
- vitamin replacement with intravenous thiamine/B12 (Pabrinex)