Jaundice Flashcards
What is jaundice and what causes it
- Yellow discolouration of the skin, eyes and other tissue.
- It is caused by a build-up of bilirubin in tissue fluids and the bloodstream.
When diagnosing liver disease, what does a doctor need to look for in the blood sample
- Increased transaminase enzymes (AST/ALT)
- Decreased levels of albumin
- Increased total amount of bilirubin
When diagnosing biliary disease, what does a doctor need to look for in the blood sample
- Increased gamma glycosyltransferase (gGT)
- Increased alkaline phosphate (AP)
Give some examples of liver tests a doctor may do to test for liver disease
- Test for bilirubin levels
- Test for liver enzymes (AST/ALT) levels
- Test for hepatobiliary enzymes (gGT, Alk Phos) levels
- Test for albumin levels
- Test for protein levels
What are some examples of tests that allow a doctor to narrow down what type of liver disease
- Antibody titre
- Haematology
- Viral Markers
- Metabolic indicators
- Tumour markers
What volume of bile is produced everyday and how many times is this volume recycled by the hepatocytes
- 0.5L per day
- Recycled 6-8 times per day
Why are bilirubin and bile salts recycled throughout the day
- Daily production of bilirubin + 250-300mg
- Daily amount required - 3.5g
How much bile can be stored in the gall bladder and what is the effect of this bile when it is released.
- A few 100ml
- Emulsifies fat in the intestine when released on demand.
What fat soluble vitamins does bile help us absorb
- Vitamin A
- Vitamin D
- Vitamin E
- Vitamin K
How does bile help process substances such as cholesterol and bilirubin
- Excretion as they cannot be cleared by the kidneys
What is bilirubin
- Raw material for bile
- Breakdown product of haemoglobin, myoglobin, cytochromes and peroxidases
How is unconjugated bilirubin produced
- Macrophages degrade old erythrocytes releasing haemoglobin molecules.
Haemoglobin is broken down into haem and globin. - Haem is oxidised by oxygenase into biliverdin (green)
- Biliverdin is reduced by biliverdin reductase to produce unconjugated bilirubin
How is unconjugated bilirubin produced
- Macrophages degrade old erythrocytes releasing haemoglobin molecules.
Haemoglobin is broken down into haem and globin. - Haem is oxidised by oxygenase into biliverdin (green)
- Biliverdin is reduced by biliverdin reductase to produce unconjugated bilirubin
How is unconjugated bilirubin produced
- Macrophages degrade old erythrocytes releasing haemoglobin molecules.
Haemoglobin is broken down into haem and globin. - Haem is oxidised by oxygenase into biliverdin (green)
- Biliverdin is reduced by biliverdin reductase to produce unconjugated bilirubin
How is conjugated bilirubin produced from unconjugated bilirubin
- Unconjugated bilirubin is carried by albumin through bloodstream to the liver (because lipid soluble)
- Hepatocytes add glucuronic acids via UPD glucuronyltransferase.
- This is now conjugated bilirubin and is water soluble
How is conjugated bilirubin excreted by the liver
- Through releasing bile from the gall bladder into the small intestine.
- When conjugated bilirubin reaches the ileum or large intestine it is converted to urobilinogen by the enzymes of epithelial or intestinal bacteria.
- Some urobilinogen is reabsorbed and transported back to the liver via the portal vein, some excreted as faeces, some transported by blood to the kidneys and excreted as urine
What are the 3 categories of causes of jaundice
- Prehepatic - cause is upstream and not liver related
- Intrahepatic - Jaundice is liver disease related
- Extrahepatic - Cause is downstream, issue occurs after bilirubin is processed in the liver
What are some key features that would suggest pre-hepatic jaundice
- High serum levels of unconjugated bilirubin
- Normal levels of liver enzymes (AST/ALT) and biliary enzymes (ALP/gGT)
What are some conditions that can cause pre-hepatic jaundice
- Haemolytic anaemia - red cell destruction
- PNS (genetic) - fragile RBCs
- Sickle Cell Disease (genetic) - Varian form of Hb present
What are some symptoms that may be present in the liver due to pre-hepatic jaundice
- Gallstones, increased bilirubin, dark urine
- Hepatomegaly, splenomegaly
- AST/ALT elevation
- Thrombosis
- Iron overload
- Hepatic thrombosis
- Coagulation deficit
- Altered MRI signal
What is the treatment plan for a patient with liver disease associate with sickle cell disease
- Aggressive manual exchange RBC transfusion (to reduce Hbs by around 30%)
- Give fresh plasma and vitamin K (help with clotting deficit due to secondary liver failure)
What is Gilbert’s Syndrome
- Mutation which decreases efficiency of UPD glucuronyltransferase when conjugating bilirubin.
- This causes increase in unconjugated bilirubin and pre-hepatic jaundice
When does jaundice appear as a symptom of gilbert’s syndrome
- During the presence of other stressors in the body
How common is neonatal jaundice (%) and why does it occur
- > 90%
- Occurs due to delay in clearance of bilirubin from RBC breakdown
