Jaundice and LFTs Flashcards
What is jaundice?
A clinical manifestation of raised bilirubin causing yellowing of the skin and sclera
What is bilirubin?
A breakdown product of the haem chain of Hb
Why does bilirubin need to be conjugated? Where does this happen?
Conjugation happens in the liver
Unconjugated bilirubin is not water soluble and needs to be transported to by attachment to albumin
Conjugated bilirubin is water soluble
After conjugation in the liver, what happens to the bilirubin?
3 options
- Excreted by the kidney in urine
- Excreted by the gut in faeces
- Enters bile
What are the 3 main types of jaundice?
- Pre-hepatic
- Hepatic
- Post-hepatic
Explain the pathophysiology of pre-hepatic jaundice
Jaundice due to increase degredation of Haemoglobin
The livers ability to conjugate is fine but the liver is overwhelmed by the increased demand of bilirubin
Will the raised bilirubin in pre-heptic jaundice be conjugated or unconjugated?
Unconjugated
As the liver cannot conjugate all the increased Hb breakdown
What common things cause pre-hepatic jaundice?
Haemoglobinopathies
- Sickle cell anaemia
- Thalassaemia
- Spherocytosis
Damage to RBC
- Haemolysis
Explain the pathophysiology of hepatic jaundice
Jaundice due to damaged hepatocytes which means the livers ability to conjugate is reduced
Will the raised bilirubin in hepatic jaundice be conjugated or unconjugated?
A mixure of both
The parts that aren’t damaged can conjugate whilst the the damaged hepatocytes cannot conjugate
What kind of things can cause hepatic jaundice?
Anything that causes cirrhosis
- Infection
- Drugs
- Autoimmune
- Alcohol
- Wilson’s Disease
- Fatty Liver Disease
- Deposition disorders
What is post hepatic jaundice?
Jaundice due to an obstruction of the extretion pathway of bilirubin from the liver
Will the raised bilirubin in post-hepatic jaundice be conjugated or uncongugated?
Conjugated as there’s nothing wrong with the liver’s ability to conjugate
What features would you see in the urine and faeces of someone with post-hepatic jaundice and why?
Dark urine and Light stools
Conjugated bilirubin is water soluble therefore more will be excreted by the kidneys and lost as urine and less in excreted by the gut and lost as faeces
Bilirubin is pigmented therefore the pigment causes the colour changes
Give some of the common causes of post-hepatic jaundice
- Gallstones
- Biliary stricture (narrowing)
- Pathology in the head of the pancreas
Why can intraheptic pathology cause post-hepatic jaundice?
Pathology such as oedema, fibrosis and malignant growths can compress the intrahepatic bile ducts
What is albumin and why is it tested to test liver function?
Albumin is the major serum protein that is produced in the liver
Reduced liver function = reduced albumin
Aside from reduced liver function, what kind of things could cause low serum albumin?
- inadequate protein intake
- increased loss via the kidneys
- physiologically less during pregnancy
Which hepatic enzymes can be tested in liver function tests?
ALT Alanine Transaminase
AST Aspartate Transaminase
Both would be raised in hepatocyte damage
Which of ALT and AST is more specific to the liver and why?
ALT
AST is also found in cardiac/ skeletal muscle and RBC
How do the levels of ALT and AST vary in acute liver damage and cirrhosis/ alcoholic hepatitis?
Acute liver damage: ALT > AST
Cirrhosis/ Alcoholic Hepatitis: AST ? ALT
The levels of which enzyme will go up in cholestatis?
ALP alkaline phosphatase
Found in cells that line the bile ducts
Aside from the liver, whereelse can ALP be found? Which test would you do to test that ALP is specifically from the liver?
ALP can also be high in bone turnover in growing children
The Gamma- Glutamyl Transferase (Gamma GT) test needs to confirm it’s specifically from the liver
What will you see in the LFTs in Pre-hepatic jandice?
- Raised unconjugated bilirubin
- Normal LFTs
- Associated anaemia
What will you see in the LFTs in Pre-hepatic jandice?
- High levels of ALT and AST
- Usually normal ALP
- Mix of conjugated and unconjugated Bilirubin
What will you see in the LFTs in Post-hepatic jandice?
- Raised levels of conjugated bilirubin
- Raised ALP
- associated increase in gamma- GT
- ALT/ AST usually normal
