Jaundice Flashcards
What is jaundice?
Yellow discolouration of the sclera and skin that is due to hyperbiliubinaemia
(bilirubin > 50umol/L)
How does jaundice occur?
Bilirubin is the normal breakdown produce from the catabolism of haemorrhage, formed from the destruction of RBCs
Under normal circumstances, bilirubin undergoes conjugation within the liver, making it water soluble.
It is then excreted via the bile into the GI tract, which is mostly egested in the faeces as urobilinogen.
10% is reabsorbed into the bloodstream and is excreted through the kidneys.
Jaundice occurs when this pathway is disrupted
What are the types of jaundice?
Pre-hepatic
Hepatoceelular
Post-hepatic
Describe pre-hepatic jaundice. Causes?
Excessive red cell breakdown overwhelms the liver ability to conjugate bilirubin.
This causes unconjugated hyperbilirubinaemia.
Any bilirubin that manages to become conjugated will be excreted normally, yet the unconjugated bilirubin will remain in the blood stream and cause jaundice
Haemolytic anaemia
Describe hepatocellular jaundice. Causes?
Dysfunction of the liver.
Liver loses its ability to conjugate bilirubin, but in cases where it also become cirrhotic, it compresses the intra-hepatic portions of the biliary tree to cause a degree of obstruction.
This leads to both unconjugated and conjugated bilirubin in the blood - mixed.
Alcoholic liver disease Viral hepatitis Medication Hereditary haemochromatosis (excessive intestinal absorption of dietary iron, which accumulates in tissues inc. liver) Autoimmune hepatitis Primary biliary cirrhosis Primary sclerosing cholangitis Hepatocellular carcinoma
Describe post-hepatic jaundice. Causes?
Obstruction of biliary drainage. Bilirubin that is not excreted will have been conjugated by the liver resulting in conjugated hyperbilirubinaemia.
Intraluminal causes - gallstones
Mural causes - cholangiocarcinoma, stricture, drug-induced cholestasis
Extramural causes - pancreatic cancer or abdominal masses (e.g. lymphomas)
How can you estimate what type of jaundice is resent?
Bilirubinuria
Conjugated bilirubin can be excreted via the urine (as it is water soluble) whereas unconjugated bilirubin cannot.
Thus, dark urine manifests in conjugated or mixed hyperbilirubinaemias (intra/post-hepatic)
Normal urine is seen in unconjugated disease (pre-hepatic)
What investigations for jaundice?
LFTs
Coagulation (PT can be used as marker of liver synthesis function)
FBC (anaemia, raised MCV - microcytic, thrombocytopenia seen in liver disease)
U&Es
Liver screen
Imaging:
USS abdomen to identify obstructive pathology or gross liver pathology
Magnetic resonance cholangiopancreatography (MRCP_ used to visualise the biliary tree - typically performed if the jaundice is obstructive but US abdomen was inconclusive or limited.
What markers are in the LFT? What do they indicate?
Bilirubin - quantify degree of suspected jaundice > 50umol/L
Albumin - marker of liver synthesising function
AST and ALT - markers of hepatocellular injury
Alkaline phosphatase - raised in biliary obstruction or bone injury
Gamma-GT - not routine in LFT, specific for biliary obstruction requested if raised ALP and unsure of cause.
What does an AST:ALT ratio > 2 indicate?
Alcoholic liver disease?
What dos AST:ALT ratio of 1 indicate?
Viral hepatitis
What is detected in a liver screen?
Viral serology: Hep A, B, C, E, CMV, EBV Non infective markers: Paracetamol levle, antinuclear antibody and IgG subtypes Alpha1 antitrypsin Caeruloplasmin Ferritin and transferrin saturation
How are obstructive causes of jaundice treated?
Removal of gallstone through endoscopic retrograde cholagiopancreatography (ERCP) or open surgery, cholecystectomy, stenting of common bile duct
