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)
Occurs 2-6 weeks before onset of symptoms
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
HBsAg:
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
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