Easy Guide to Interpreting Hepatitis B Test Results
The most straightforward way to interpret Hepatitis B test results is to focus on three key markers: HBsAg (surface antigen), anti-HBc (core antibody), and anti-HBs (surface antibody), which together determine infection status and immunity.
Key Hepatitis B Markers and Their Interpretation
Primary Serological Markers
| Marker | Positive Indicates |
|---|---|
| HBsAg | Current HBV infection (acute or chronic) |
| Anti-HBc | Previous or ongoing HBV exposure |
| Anti-HBs | Immunity (from vaccination or resolved infection) |
Comprehensive Interpretation Table
| HBsAg | Total Anti-HBc | IgM Anti-HBc | Anti-HBs | Interpretation |
|---|---|---|---|---|
| Negative | Negative | Negative | Negative | Never infected, susceptible |
| Positive | Negative | Negative | Negative | Early acute infection |
| Positive | Positive | Positive | Negative | Acute infection |
| Negative | Positive | Positive | Negative | Acute resolving infection |
| Negative | Positive | Negative | Positive | Recovered from past infection and immune |
| Positive | Positive | Negative | Negative | Chronic infection |
| Negative | Positive | Negative | Negative | Several possibilities* |
| Negative | Negative | Negative | Positive | Vaccine-induced immunity |
*Possibilities include false positive, past infection with waning immunity, "low-level" chronic infection, or passive transfer to infant born to HBsAg-positive mother 1.
Distinguishing Acute vs. Chronic Infection
- Acute infection: Presence of HBsAg and IgM anti-HBc 1
- Chronic infection: HBsAg persists for more than 6 months, with positive total anti-HBc but negative IgM anti-HBc 1
Additional Markers for Chronic Infection Management
For patients with chronic HBV infection, additional markers help determine disease phase:
HBeAg and anti-HBe: Indicate viral replication level
- HBeAg-positive: High viral replication (typically >20,000 IU/mL)
- HBeAg-negative, anti-HBe-positive: Lower viral replication (<2,000 IU/mL in inactive carriers) 1
HBV DNA: Quantifies viral load
- <2,000 IU/mL with normal ALT: Suggests inactive carrier state
2,000 IU/mL with elevated ALT: Indicates active hepatitis 1
Differentiating Vaccine-Induced vs. Natural Immunity
- Vaccine-induced immunity: Positive anti-HBs only, negative anti-HBc
- Natural immunity: Positive anti-HBs AND positive anti-HBc 1, 2
Common Pitfalls in Interpretation
Window period: During acute infection resolution, HBsAg may disappear before anti-HBs appears. During this period, IgM anti-HBc may be the only detectable marker 1.
Isolated anti-HBc: When only anti-HBc is positive, consider:
- Resolved infection with waned anti-HBs
- False positive result
- Occult hepatitis B infection (HBV DNA testing recommended) 1
Simultaneous HBsAg and anti-HBs: Though uncommon, this can occur in some chronic infections and is associated with poorer prognosis 3.
Quantitative HBsAg: Newer assays measuring HBsAg levels can help monitor treatment response and identify true inactive carriers (HBsAg <100 IU/mL has 97% probability of indicating inactive disease) 4, 5.
By focusing on these key markers and understanding their patterns, clinicians can accurately determine a patient's hepatitis B status and make appropriate management decisions to improve mortality and morbidity outcomes.