Anti-HBc IgM is a blood test that detects the IgM antibody against the core antigen of Hepatitis B.
It is mainly used to identify a recent (acute) Hepatitis B infection.
🦠 What It Targets
HBcAg = core antigen (found inside the virus)
IgM = the first antibody produced during a new infection
🔬 Interpretation of Results
| Result | Meaning |
|---|---|
| Positive | Recent/acute HBV infection (usually within the last ~6 months) |
| Negative | No recent infection |
⭐ Important: Window Period
During the window period (when HBsAg has disappeared but Anti-HBs has not yet formed), Anti-HBc IgM may be the only positive marker.
🧪 Comparison with Other Hepatitis B Markers
| Test | What It Indicates |
|---|---|
| HBsAg | Current infection |
| Anti-HBs | Immunity |
| Anti-HBc Total | Past or current exposure |
| Anti-HBc IgM | Recent/acute infection |
📝 Key Points
IgM = early immune response
Positive Anti-HBc IgM = new infection
The vaccine does NOT cause Anti-HBc antibodies
Helps diagnose acute hepatitis B
If you’d like, share your full hepatitis B panel results and I can help explain what they mean step-by-step.
