Hepatitis testing – Which test to order?

1. Principles of hepatitis testing

  Consider the incubation periods:

Hepatitis A: 2 - 6 weeks

Hepatitis B: 1 - 6 months

Hepatitis C: 15 days - 5 months

  Types of antibodies:

IgM is detected in recent infection and lasts for about 3 months

IgG alone occurs with past infection, carrier states and vaccination

IgM & IgG occur together in recent infection

2. The jaundiced patient - ?Acute (infectious) hepatitis

  Is this Hepatitis A, B or C?

  Also consider:

EBV, CMV

Non-infectious causes of jaundice (biliary obstruction, medications, alcohol)

3. Testing for acute hepatitis

  HBsAg (hepatitis B surface antigen)

If HBsAg detected, request HBcIgM (hepatitis B core IgM antibody - usually present at onset of symptoms).

  HAV IgM

Occurs with onset of abnormal LFTs

  HCV Ab / Anti-HCV

Present at onset of symptoms in 50 -70% patients

Occurs by 20 weeks in 95% patients

If negative early, repeat if no other cause found

4. Antenatal hepatitis screen

  HBsAg - To detect maternal chronic hepatitis B infection (‘carrier’)

  (HCV antibody only if requested)
 

5. Post Vaccination Check

Hepatitis B vaccination

Check HBsAb (Anti-HBs, hepatitis B surface antibody)

Timing: 4 weeks after 3rd vaccination

If negative, consider checking for HBsAg (hepatitis B surface antigen) carriage

Hepatitis A vaccination

Anti-HAV Total antibody

  Note - There is no hepatitis C vaccination available currently
 

6. Blood or body fluid exposure (eg. needlestick injury / mucosal splash)

  Source (eg. patient):

HBsAg, HCV Ab (Anti-HCV), HIV Ab (Anti-HIV)

  Recipient (eg. healthcare worker):

HBsAb (Anti-HBs) + baseline LFTs if ‘Source’ hepatitis serology positive

Store serum for 2 years

7. Possible hepatitis B ‘carrier’ (chronic hepatitis B infection)

Check HBsAg

If HBsAg detected then check

- HBeAg and HBeAb (Anti-HBe)
- HBV DNA

8. Possible chronic hepatitis C infection

Check HCV Ab (Anti-HCV)

If detected, then check Hep C PCR

9. Tests for patients at risk of blood borne viruses

If negative check HBcAb (Anti-HBc, hepatitis B core antibody) for previous infection

If detected check HBeAg, HBeAb (Anti-HBe) & HBV DNA to assess infectivity

HCV Ab (Anti-HCV): If detected, check Hep C PCR

Anti-HAV Total antibody: If at risk of hepatitis A prior to immunisation (eg injecting drug users, men who have sex with men).

10. GLOSSARY

Call the Core Laboratory 9895 3471 and speak to the Senior Scientist.

Compiled by Dr Mary O'Reilly, Head of Eastern Health Infectious Diseases & Infection Control.