Initial Serologic Testing for Hepatitis B Infection
The initial serologic testing for hepatitis B infection should include three tests: hepatitis B surface antigen (HBsAg), total antibody to hepatitis B core antigen (anti-HBc), and antibody to hepatitis B surface antigen (anti-HBs). 1, 2
Core Three-Test Panel
This three-marker panel serves as the baseline serologic assessment and allows differentiation between acute infection, chronic infection, resolved infection, and vaccine-induced immunity 1, 2:
- HBsAg identifies active HBV infection (either acute or chronic) and is the hallmark marker that appears first, typically 30 days after exposure (range: 6-60 days) 1
- Total anti-HBc (IgG plus IgM) distinguishes natural infection from vaccine-induced immunity, as it persists for life after HBV exposure but is absent in vaccinated individuals 1, 2
- Anti-HBs indicates immunity from either vaccination or past cleared infection 1, 2
Interpretation Algorithm
The combination of these three markers provides distinct diagnostic patterns 1, 2:
- All three negative: Patient is susceptible to HBV and requires vaccination 2
- HBsAg positive: Active infection present (acute or chronic); proceed to additional testing including IgM anti-HBc to distinguish acute from chronic infection 1
- Anti-HBs positive alone (anti-HBc negative): Immunity from vaccination 1
- Anti-HBs and anti-HBc both positive (HBsAg negative): Resolved past infection with immunity 1
- Isolated anti-HBc positive: Requires careful interpretation—may represent waning anti-HBs after remote infection, occult hepatitis B, or false positive result 1, 2
Additional Testing When HBsAg is Positive
If HBsAg is positive, confirming active infection, the initial evaluation should be expanded to include 1:
- IgM anti-HBc: Distinguishes acute infection (IgM positive) from chronic infection (IgM negative or low-level positive) 1
- HBV DNA quantitative: Assesses viral replication level 1
- HBeAg and anti-HBe: Indicates replication phase—HBeAg positivity generally indicates high viral replication 1
- Liver function tests (ALT/AST): Assesses hepatic inflammation 1
Critical Pitfalls to Avoid
Do not order only HBsAg alone for initial screening, as this misses individuals with resolved infection who may need counseling, and fails to identify those needing vaccination 1, 2. The isolated anti-HBc pattern (positive anti-HBc with negative HBsAg and anti-HBs) occurs in 10-20% of HBV-infected persons in low-prevalence populations and requires HBV DNA testing to rule out occult hepatitis B, particularly in immunocompromised patients 1, 2.
Chronic infection is defined as HBsAg persistence beyond 6 months, not by a single positive test, though in patients presenting de novo with clinical or epidemiologic factors suggesting chronic infection, the 6-month waiting period is not necessary 1. IgM anti-HBc should only be ordered when acute hepatitis is clinically suspected, as its positive predictive value is low in asymptomatic persons 1.