Jaundice Flashcards
What is jaundice?
Yellowing of the skin, sclerae, and mucosae from increased plasma bilirubin (visible >60umol/L).
How is jaundice classified?
- Site - prehepatic, hepatocellular, or cholestatic/obstructive.
- Type of circulating bilirubin - conjugated or unconjugated
What are the steps of conjugated bilirubin production, starting at red blood cells?
- RBCs broken down by macrophage into globin and heme.
- Heme broken down into iron and protoporphyrin which becomes unconjugated bilirubin.
- Unconjugated bilirubin is transported from the reticular endothelial system to the liver bound to albumin.
- In the liver hepatocytes, uridine glucuronyl transferase convert unconjugated bilirubin to conjugated bilirubin (glucuronic acid).
How is conjugated bilirubin broken down in the small intestine?
- Conjugated bilirubin is broken down by microbes into urobilinogen.
- This then breaks down into stercobilin which is excreted, or absorbed into the blood becoming urobilin.
- Urobilin transported to the liver and kidneys for excretion.
What is the pathway of the enterohepatic circulation?
Liver, bile, small intestine, enterocyte, hepatic portal vein, liver.
What causes a raised unconjugated bilirubin?
Overproduction (haemolysis), impaired hepatic uptake, impaired conjugation, physiological neonatal jaundice.
What causes a raised conjugated bilirubin?
Hepatocellular dysfunction, cholestasis.
What are the prehepatic causes of jaundice?
Haemolytic disorders - G6PD, thalassemia, sickle cell anaemia, autoimmune haemolytic anaemia
What are the hepatocellular causes of jaundice?
- Gilbert’s syndrome - benign, mild jaundice during fasting or illness.
- Acute liver injury - toxic, infective, autoimmune, metabolic and vascular liver insults.
- Cirrhosis - chronic liver injury from any cause.
- Hepatic tumours - metastatic
What are the results in the LFTs in a hepatocellular cause of jaundice?
Disproportionate rise in ALT and AST relative to ALP and GGT.
What are the post hepatic causes of jaundice?
- Gallstones - most common, relatively rapid onset.
- Benign strictures - trauma from surgery or consequence of inflammation.
- Autoimmune - primary biliary cirrhosis or primary sclerosing cholangitis.
- Malignancy - painless jaundice
What are the results in the LFTs in a post hepatic cause of jaundice?
Pronounced rise in ALP and GGT.
What is the effect of a post hepatic cause of jaundice on the clotting screen?
Raised PT time due to vitamin K malabsorption from the gastrointestinal tract.
Which drug causes prehepatic jaundice?
Anti malarial (Dapsone)
Which drugs cause hepatic jaundice?
Paracetamol overdose, cocaine, ecstasy, aspirin/NSAIDs, anti TB medication, antifungal (ketoconazole), antihypertensives (methyl-dopa).
Which drugs cause post hepatic jaundice?
Penicillin, macrolides, azathioprine, oestrogens, amitriptyline, carbamazepine, ACEi, cimetidine, ranitidine.
What are the risk factors for developing jaundice?
Alcohol, IVDU, sexual activity, piercings, tattoos, hepatitis B/C, blood transfusions, travel abroad, family history, medications.
What are the symptoms of jaundice?
Yellow skin/sclera, fatigue, malaise, pruritus, weight loss, anorexia, pale stool, dark urine, may have severe RUQ pain preceding.
What are the features of pre-hepatic jaundice on examination?
Mild jaundice, anaemia, splenomegaly, haematuria.
What are the features of hepatic jaundice on examination?
Signs of liver failure: spider naevi, clubbing, palmar erythema, gynaecomastia, ascites, asterixis, hepatic encephalopathy, CAGE score >2.
What are the features of post-hepatic jaundice on examination?
Hepatomegaly, palpable gallbladder, masses, scars.
What are the causes of jaundice in a previously stable patient with cirrhosis?
Sepsis (UTI, pneumonia, peritonitis), malignancy, alcohol, drugs, GI bleed.
What are the results of unconjugated serum bilirubin (indirect) in pre-hepatic, hepatic, and post-hepatic jaundice?
Pre-hepatic - increase
Hepatic - increased
Post-hepatic - slightly increased
What are the results of conjugated serum bilirubin (direct) in pre-hepatic, hepatic, and post-hepatic jaundice?
Pre-hepatic - normal
Hepatic - increased
Post-hepatic - moderately increased
What are the results of ALT in pre-hepatic, hepatic, and post-hepatic jaundice?
Pre-hepatic - normal
Hepatic - markedly increased
Post-hepatic - increased
What are the results of ALP in pre-hepatic, hepatic, and post-hepatic jaundice?
Pre-hepatic - normal
Hepatic - increased
Post-hepatic - markedly increased
What are the results of GGT in pre-hepatic, hepatic, and post-hepatic jaundice?
Pre-hepatic - normal
Hepatic - increased
Post-hepatic - markedly increased
What are the results of INR in pre-hepatic, hepatic, and post-hepatic jaundice?
Pre-hepatic - normal
Hepatic - increased
Post-hepatic - increased
What are the results of urine bilirubin in pre-hepatic, hepatic, and post-hepatic jaundice?
Pre-hepatic - 0 (normal)
Hepatic - present
Post-hepatic - present (via blood leak)
What are the results of urine urobilinogen in pre-hepatic, hepatic, and post-hepatic jaundice?
Pre-hepatic - increased
Hepatic - increased
Post-hepatic - 0 (duct blocked)
What are the results of urine in pre-hepatic, hepatic, and post-hepatic jaundice?
Pre-hepatic - normal
Hepatic - dark
Post-hepatic - dark
What are the results of faeces in pre-hepatic, hepatic, and post-hepatic jaundice?
Pre-hepatic - normal
Hepatic - pale
Post-hepatic - pale
What investigations should be carried out in jaundice?
- LFTs, GGT, PT, total protein, albumin, urine, FBC, malaria parasites, U&Es
- USS to see if bile ducts are dilated - gallstones, hepatic metastases, pancreatic mass
What is the management for jaundice?
- Treat the cause
- Adequate hydration
- Broad spectrum antibiotics if obstruction
- Monitor for ascites and encephalopathy
