Friday, 24 September 2010

MRCP revision battle 19.2: Hepatitis

There are 5 'flavours' of viral hepatitis, labeled A to E.  Important general points to learn are:
  • all are caused by RNA virus' except hepatitis B, which is a DNA virus
  • B and C are spread by blood/sexual contact
  • A and E are spread by the faecal-oral route
  • Hepatitis D essentially is only ever found as a co-infection, never alone.

So to explore the 3 most popular MRCP 'flavours' in more depth....

Hepatitis A:
  • spread faeco-orally, so look out for questions featuring backpackers returning home
  • incubation period is 2-6 weeks
  • presents as fever, malaise, nausea
  • patient likely to be jaundiced and may have hepato/splenomegaly
  • treatment is supportive
  • patients generally make a full recovery

Hepatitis B:
  • symptoms are similar to hep A
  • incubation period is longer at 1 - 6 months
  • spread is blood/bodily fluids - questions likely to hint at male business traveller or other innuendo
  • important to fully grasp the various antigens and their meanings:
    • HBsAg: present for 1-6 months after exposure; if present for >6 months patient is a carrier
    • HBeAg: present for 1.5-3 months after exposure and is marker of high infectivity
    • anti HBC IgM - signifies acute infection/carrier
    • anti HBC IgG - may be acute infection, carrier or cleared infection
    • anti HBS - if present with anti HBC suggests recovered from hep B and naturally immune; if present alone suggests hep B vaccination
  • complications of hepatitis B include:
    • 5-10% chronic hepatitis
    • glomerulonephritis
    • increased risk hepatocellular carcinoma
    • cryoglobulinaemia

Hepatitis C:
  • is spread by blood/sexual contact
  • blood pre 1991 wasn't screened for hep C
  • <20% get an acute hepatitis but 80% get chronic hepatitis
  • breast feeding is NOT contraindicated (a common MRCP fascination for some reason)
  • complications:
    • 80% chronic hepatitis
    • 20% cirrhosis
    • increased risk hepatocellular carcinoma
  • Treatment: IFN alpha and ribavirin

After that wizz through some high-yield viral hepatitis facts lets move on to Peutz Jegher Syndrome