Jaundice Flashcards
What are the three steps of bilirubin metabolism?
Production of unconjugated bilirubin
Conjugation of bilirubin
Excretion of bilirubin
How does unconjungated bilirubin travel to the liver?
Bound to albumin
Where are blood cells normally broken down?
In the spleen by splenic macrophages
What is bilirubin conjugated with in the liver?
Glucuronic acid
What is conjugated bilirubin converted to within the intestines and what happens to these products?
Urobilinogen and stercobilinogen
Some of the urobilinogen is reabsorbed by the intestines and excreted by the kidneys
Stercobilinogen gets converted to stercobilin, which gives faeces its brown colour
What are the three main types of jaundice?
Pre-hepatic
Hepatic
Post-hepatic (obstructive)
What characteristic clinical features are associated with obstructive jaundice?
Dark urine
Pale stools
What are the two mechanisms of unconjugated hyperbilirubinaemia?
Increased production of bilirubin (increased haemolysis)
Decreased capacity to conjugate bilirubin
Why might patients who are undergoing intravascular haemolysis have dark urine?
Free haemoglobin from the haemolysis is degraded into haemosiderin, which is water soluble and very dark
List some congenital causes of intravascular haemolysis.
G6PD deficiency
Pyruvate kinase deficiency
Sickle cell disease
Thalassemia
List some acquired causes of intravascular haemolysis.
Artificial heart valves Blood group mismatch DIC Malaria Medications
What might be seen on the blood film of a patient undergoing intravascular haemolysis?
Schistocytes
Which clinical sign is likely to be seen in patients undergoing extravascular haemolysis?
Splenomegaly
List a congenital and acquired cause of extravascular haemolysis.
Congenital – hereditary spherocytosis
Acquired – autoimmune haemolytic anaemia
What can cause reduced uptake of bilirubin by the liver?
TIPS (transjugular intrahepatic portosystemic shunt)
Name two congenital enzymatic problems that lead to unconjugated hyperbilirubinaemia.
Gilbert’s syndrome
Crigler-Najjar syndrome
Name a congenital cause of obstructive jaundice.
Dubin-Johnson syndrome
Using the surgical sieve, list causes of obstructive jaundice.
Infection – hepatitis, ascending cholangitis, liver abscess
Neoplasia – HCC, cholangiocarcinoma, pancreatic cancer
Vascular – Budd-Chiari syndrome
Inflammation/Autoimmune – PBC, PSC, autoimmune hepatitis, pancreatitis
Trauma – gallstones, strictures
Endocrine – intrahepatic cholestasis of pregnancy
Degenerative
Metabolic – haemochromatosis, Wilson’s disease
Drugs – alcohol, paracetamol, sodium valproate, co-amoxiclav
List some key features of the history of presenting complaint that you should ask a patient with jaundice.
Acute or chronic
RUQ pain, nausea and vomiting – suggests hepatobiliary
Fever and diarrhoea – suggest infection
Steatorrhoea, dark urine, pruritus – suggests obstructive
Weight loss, fever, night sweats – systemic features of malignancy
Bronzed skin and signs of diabetes mellitus – haemochromatosis