Jaundice Flashcards
What is jaundice?
Yellowing of skin, sclerae (eyeball) and mucosae due to increased plasma bilirubin
Describe bilirubin metabolism
Haemoglobin is broken down into Haem and Globin
Haem is broken into porphyrin and iron
Porphyrin is converted into unconjugated haemoglobin
Unconjugated haemoglobin is taken up by the liver
In the liver bilirubin is conjugated with glucuronic acid by hepatocytes making it water soluble
Conjugated bilirubin is secreted in bile and passes into gut
Some is taken up again by liver (entero-hepatic circulation)
The rest is converted into urobilinogen by gut bacteria
either excreted in kidneys or converted to stercobilinogen which colours faeces
A rise in unconjugated bilirubin indicates a pre hepatic problem, what are the causes of rises in unconjugated bilirubin?
Overproduction; haemolysis/ ineffective erythropoieseisis
Impaired hepatic uptake; drugs (rifampicin)
Right heart failure
Impaired conjugation: Gilbert’s syndrome
Neonatal jaundice is a combination of the above
What are causes of hepatic jaundice?
Viruses: Hepatitis, EBV, CMV
Drugs: paracetamol, isoniazid, rifampicin & pyrazimamide (TB), statins, sodium valproate
Alcohol
Liver metastases/ abscesses
Haemachromatosis
Autoimmune hepatitis
alpha 1 antitrypsin deficiency (alpha 1 antitrypsin protects cells in liver and lungs from neutrophil trypsin)
Septicaemia
Syphilis
Wilsons
Post hepatic jaundice is caused by impaired hepatic excretion.
What are causes of post hepatic jaundice?
Primary biliary cirrhosis
Primary sclerosing cholangitis
Common bile duct gall stones
Pancreatic/ gallbladder cancer
Drugs: Flucloxacillin, Steroids, The pill, Sulfonylureas (anti-diabetic), Prochlorperazine (antiemetic), Chlorpromazine (schizophrenia med)
Symptoms of conjugated hyperbilirubinaemia?
As conjugated bilirubin is soluble, it is excreted in the urine making it dark
Less conjugated bilirubin enters the gut—> Faeces become pale
