Hepatitis B Laboratory Testing: A Practical Guide
Initial Screening Panel
Order HBsAg, anti-HBs, and anti-HBc as the initial three-test panel to determine HBV infection and immunization status. 1
This combination efficiently distinguishes between:
- Active infection (chronic or acute)
- Past resolved infection with immunity
- Vaccine-induced immunity
- Susceptibility requiring vaccination
Interpreting the Core Serologic Patterns
Immunity from Vaccination
- Anti-HBs positive, anti-HBc negative, HBsAg negative 1, 2
- This pattern confirms successful immunization without prior natural infection
- Anti-HBc remains negative because it only appears after actual HBV infection 1
Immunity from Past Infection
- Anti-HBs positive, anti-HBc positive, HBsAg negative 1, 2
- Indicates resolved infection with natural immunity
- Anti-HBc persists for life after infection 1
Chronic HBV Infection
- HBsAg positive for >6 months, anti-HBc positive, anti-HBs negative 1, 2
- HBsAg persistence beyond 6 months defines chronic infection by definition 1
- Requires additional workup (see below)
Acute HBV Infection
- HBsAg positive, IgM anti-HBc positive 1, 2
- IgM anti-HBc is the specific marker distinguishing acute from chronic infection 1
- IgM anti-HBc remains detectable for approximately 6 months after acute infection 1
Critical Pitfall: Isolated Anti-HBc Positive
When anti-HBc is positive but both HBsAg and anti-HBs are negative, this requires careful interpretation 1, 2:
Two possible explanations exist:
- Anti-HBs has declined to undetectable levels after remote resolved infection 1
- Occult hepatitis B infection (HBsAg undetectable but virus present) 1, 2
Management approach:
- Order HBV DNA testing to detect occult infection 1, 2
- Repeat HBsAg, anti-HBs, and anti-HBc in 3-6 months 1
- This pattern can also occur during the "window period" of acute infection when HBsAg has cleared but anti-HBs has not yet appeared 1, 2
Additional Testing for Confirmed Chronic HBV
Once chronic infection is confirmed (HBsAg positive >6 months), obtain the following 1:
Viral Replication Markers
Liver Function Assessment
- AST/ALT, alkaline phosphatase, GGT, bilirubin, albumin, prothrombin time 1
- Complete blood count 1
- Creatinine 1
Coinfection Screening
- Anti-HCV in all patients 1
- Anti-HDV in patients with history of injection drug use 1
- Anti-HIV in high-risk groups 1
Hepatitis A Immunity Status
- IgG anti-HAV in patients younger than 50 years 1
- Coinfection with hepatitis A in HBV carriers significantly increases mortality risk 1
- Vaccinate if negative 1
HCC Surveillance Baseline
- Ultrasound and serum α-fetoprotein 1
Special Testing Considerations
Post-Vaccination Testing
Not routinely recommended for immunocompetent adults due to near-universal seroconversion 1
Testing 1-2 months after completion of vaccine series IS recommended for: 1
- Healthcare workers
- Dialysis patients and dialysis unit workers
- Immunocompromised patients (HIV infection, stem cell transplant recipients, chemotherapy patients)
- Sexual partners of HBV-infected persons
- Newborns of HBV-infected mothers
Target anti-HBs level: ≥10 mIU/mL indicates protective immunity 1
Distinguishing Vaccine vs. Natural Immunity
When determining immunity source (important for healthcare workers and occupational exposure assessment):
- Anti-HBs positive alone = vaccine-induced immunity 1, 2
- Anti-HBs positive + anti-HBc positive = natural immunity from past infection 1, 2
Common Testing Errors to Avoid
Ordering only HBsAg without anti-HBs and anti-HBc fails to distinguish susceptible patients who need vaccination 1
Assuming isolated anti-HBc positive is always past infection without checking HBV DNA misses occult hepatitis B 1, 2
Failing to order IgM anti-HBc when acute infection is suspected prevents distinguishing acute from chronic infection 1, 2
Not repeating HBsAg at 6 months to confirm chronicity in patients with acute infection 1
Ordering anti-HBc alone as a screening test is insufficient because it cannot distinguish active infection from resolved infection 1