8. Hepatitis Flashcards
what is hepatitis?
inflammation of the liver
what kind of viruses cause liver damage?
- many systemic viruses cause ‘collateral’ liver damage, e.g. EBV, CMV, VZV
- hepatitis viruses
- replicate specifically in hepatocytes (hepatotropic)
- destruction of hepatocytes - replication causes fibrosis and inflammation… cirrhosis and liver cancer
How are HepB and HepC transmitted, how long incubation, and acute or chronic illness?
HepB
- blood/sex/vertical transmission
- 6wks-6mths incubation
- acute or chronic illness
HepC
- blood/sex transmission
- 6-12wks incubation
- chronic illness
What type of virus are hepB and hepC
- HepC= RNA virus
- HepB = DNA virus
what causes jaundice in hepatitis patients?
accumulation of bilirubin due to liver dysfunction
how is bilirubin produced and excreted?
- haemoglobin in aged RBCs broken down by reticuloendothelial system to produce bilirubin
- transported in bloodstream to liver via albumin
- conjugation of bilirubin in liver by UDP glucuronyl transferase to make it soluble
- a) some excreted in urine (yellow)
b) some added to bile and excreted in faeces (brown) via GI tract
where is bile produced, stored and released?
produced in liver, stored in gallbladder and released into duodenum for fat digestion
what is cholestasis?
- reduction or stoppage of bile flow
- can be intrahepatic (in liver) or extrahepatic (ducts, gallbladder or pancreas)
what are the 3 main types of jaundice? how is each caused?
- Prehepatic
- increased haemolysis - Cholestatic - intrahepatic
- viral hepatitis
- drugs
- alcoholic hepatitis
- cirrhosis
- autoimmune cholangitis
- pregnancy
- … - Cholestatic - extrahepatic
- common duct stones
- carcinoma (bile duct, head of pancreas, ampulla)
- biliary stricture
- …
which liver function tests (LFTs) are used to test for cellular integrity?
- bilirubin
- liver transaminases
- alanine transaminase (ALT) - more sensitive
- aspartate aminotransferase (AST) - alkaline phosphatase (ALP) - produced by cells of biliary tree
which LFT would indicate hepatocyte damage/decreased cellular integrity?
increased alanine transaminase (ALT) or aspartate aminotransferase (AST)
which LFT would indicate biliary tract cell damage/cholestasis?
increased alkaline phosphatase (ALP)
which LFTs are used to assess liver function?
- albumin (protein synthesised in liver so decreased in fibrosis/cirrhosis)
- coagulation tests (clotting factors synthesised in liver)
- INR (international normalised ratio)
- prothrombin time (PT)
What are the symptoms of acute hepB infection?
Up to 50% have no/vague symptoms
- jaundice
- fatigue
- abdominal pain, nausea and vomiting
- arthralgia
What are the 3 possible consequences of acute hepB infection?
- infection clearance within 6 mths - lifelong immunity
- chronic infection (<10% adult infections, 90% infancy infections)
- fulminant hepatic failure (1%)
What are the possible complications of chronic hepB?
- cirrhosis (25%)
- hepatocellular carcinoma (5%)
Name 3 diagnostic measures for hepB.
- AST/ALT in 1000s
- serology: detection of Ag and Ab
- PCR for HepB DNA
Describe the appearance of Ag and Ab in hepB infection (in order).
- surface antigen (HBsAg)
- e-antigen (HBeAg) - highly infectious
- core antibody (IgM) - in resp. to HBcAg (not detectable)
- e-antibody - indicates disappearance of e-antigen and infectivity
- surface antibody - last antibody to appear, indicates virus clearance/recovery
- core antibody (IgG) - persists for life
Describe the treatment of chronic HepB infection.
No cure as viral DNA integrates into host genome - life-long anti-virals to suppress viral replication.
Not required for everyone: ‘inactive’ carriers - low viral load, normal LFTs, no liver damage (but require monitoring).
How likely is chronic disease dev. after acute HepC infection?
80%
What is the consequence of some chronic HepC infections?
Chronic liver disease/cirrhosis resulting in:
- decompensated liver disease
- hepatocellular carcinoma
- death
May require transplant.
What are the symptoms of HepC infection?
80% have no symptoms (acute or chronic), 20% have vague symptoms:
- fatigue
- nausea & anorexia
- abdominal pain (RUQ)
Name 2 diagnostic measures for HepC.
- serology: anti-HepC antibody only (remains +ve life long even after clearance, but not protective)
- PCR for HCV DNA
Describe the treatment of HepC infection.
> 90% cured with directly acting antiviral drug combination (but expensive and can get re-infected)
Describe the vaccination strategies for HepB and HepC.
- HepB: genetically engineered surface antigen (3 doses + boosters if required) - effective in most people. Produces surface Ab response (>10 adequate, >100 long-term protection)
- HepC: no vaccine
