A 32-year-old man from Delhi presents with jaundice, malaise, and dark urine for 2 weeks. Liver function tests show elevated transaminases (ALT 1200 U/L, AST 950 U/L) and bilirubin 8 mg/dL. HBsAg is positive on screening. Which investigation is most appropriate to differentiate acute hepatitis B from chronic hepatitis B?

Explanation

## Differentiation of Acute vs Chronic Hepatitis B **Key Point:** Anti-HBc IgM is the gold standard marker for acute hepatitis B infection and appears early in the course of disease, making it the most appropriate confirmatory test in this clinical scenario. ### Serological Markers in HBV Infection | Marker | Acute HBV | Chronic HBV | Interpretation | |--------|-----------|-------------|----------------| | **HBsAg** | Present | Present | Indicates active infection (not differentiating) | | **Anti-HBc IgM** | **Present (early)** | **Absent** | **Acute infection** | | **Anti-HBc total** | Present | Present | Cannot differentiate | | **HBeAg** | Often present | Variable | Indicates replication, not phase | | **Anti-HBe** | Appears late | Often present | Late marker, not differentiating | **High-Yield:** Anti-HBc IgM appears within the first 1–2 weeks of acute infection and disappears within 6 months. Its presence in an HBsAg-positive patient definitively confirms acute hepatitis B. ### Clinical Pearl In this patient with acute presentation (jaundice, elevated transaminases, dark urine for 2 weeks), the clinical picture is consistent with acute viral hepatitis. Anti-HBc IgM will confirm HBV as the causative agent and differentiate it from chronic HBV (where Anti-HBc IgM is absent). ### Mnemonic: IgM = Immediate (acute) IgM antibodies appear early in acute infection; IgG (total anti-HBc) appears later and persists in both acute and chronic disease. **Warning:** Anti-HBc total (IgG + IgM) is present in both acute and chronic HBV and cannot differentiate between them. HBeAg and Anti-HBe reflect viral replication status, not the phase of infection.