Jaundice + LFTs Flashcards
Where does the process of bilirubin metabolism begin?
What occurs here?
- Spleen
- Haemoglobin is broken down into haem +globin
- haem > biliverdin > unconjugated bilirubin
What is the role of albumin in bilirubin metabolism?
Unconjugated bilirubin is not water soluble + must bind to albumin for transport through the blood stream to the liver
Where does bilirubin conjugation occur?
In the liver
Describe the process of bilirubin conjugation
- in the liver
- bilirubin is combined with glucuronic acid
- this makes bilirubin water soluble + able to be excreted
What are the classification of jaundice?
Pre-hepatic
Hepatic
Post hepatic
Based on their location
What is pre hepatic jaundice due to?
- Excessive red bleed cell breakdown - haemolysis
- High unconjugated bilirubin beyond the ability of the liver to conjugate it
What is hepatic jaundice due to?
Impaired bilirubin processing in the liver
High conjugated + unconjugated bilirubin
What is post hepatic jaundice due to?
Obstruction in the bile ducts which prevents normal bile flow from the liver
High conjugated bilirubin
e.g. gallstones
Condition which can cause pre hepatic jaundice
- Haemolytic anaemias e.g. sickle cell, thalassaemia
- Infections e.g. malaria
- Medications
Presentation of post hepatic jaundice
Dark urine
Pale stool
Abdominal discomfort
High conjugated bilirubin levels
Causes of post hepatic jaundice
Gallstones
Inflammation of bile duct
Pancreatic tumours
Biliary atresia
Causes of hepatic jaundice
Acute viral hepatitis
Paracetamol toxicity
Cirrhosis
What is included in LFTs?
Albumin
ALT alanine transaminase
AST aspartate transaminase
ALP alkaline phosphate
Bilirubin
Why is ALT more specific to the liver than AST?
AST is also found in:
- skeletal muscle
- cardiac muscle
- RBCs
Is ALT or AST more specific to the liver?
ALT
