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
ALT is higher in …. liver damage
AST is higher in ….. liver damage
ALT is higher in acute liver damage
AST is higher in chronic liver damage
Where is ALP alkaline phosphatase found?
Bile duct
What is cholestatis?
Obstruction in the bile duct
What test is used to see if ALP is coming from the liver?
Gamma GT
Where else can ALP be released from is the liver isnt damaged?
Bone
e.g. high in children due to high bone turnover
What type of bilirubin can cross the blood brain barrier?
Unconjugated
What is conjugated bilirubin broken down into?
Stercobilin in duodenum
Urobilinogen in kidney
What blood test could be used to confirm prehepatic jaundice in a new born baby?
FBC
A raised level of what on a LFT would be indicative of a blockage in the common bile duct?
Conjugated bilirubin is the most specific
ALP rises but is less specific (+GGT)
What does raised ALP indicate?
What addition blood test results backs this up?
Biliary tree damage
Raised GGT
What is a raised GGT in isolation indicative of?
Chronic alcohol misuse
What does raised amylase indicate?
Pancreas damage
LFT results of hepatocyte damage
- Raised ALT + AST
- Reduce albumin (reduced synthetic function)
Blood tests to confirm pancreas damage
Amylase
Lipase
What is raised ALP + GGT indicative of?
Biliary tree damage
Cholestasis
Gall stones
LFT results of pre haptic jaundice
Normal ALT, AST + ALP
Raised unconjugated bilirubin
Why do patients with post hepatic jaundice also present with pale faeces and dark urine?
- Reduced stercobilin in faeces > pale
- Conjugated bilirubin in urine > dark
What is combined with unconjugated bilirubin to produce conjugated bilirubin?
Why is this needed?
Glucuronic acid
To make it water soluble to be excreted
