A 35-year-old man from Mumbai presents with jaundice, dark urine, and right upper quadrant pain for 2 weeks. He has no history of alcohol use or IV drug abuse. Laboratory investigations show: ALT 1200 IU/L, AST 980 IU/L, bilirubin 8.2 mg/dL, and INR 1.1. Serological testing reveals: HBsAg positive, anti-HBs negative, anti-HBc IgM positive, HBeAg positive, anti-HBe negative. What is the most likely interpretation of these findings?

Explanation

## Interpretation of Hepatitis B Serology ### Clinical Presentation The patient presents with acute hepatitis (markedly elevated transaminases, hyperbilirubinemia, normal INR) with a 2-week history — consistent with acute viral hepatitis. ### Serological Marker Analysis | Marker | Result | Interpretation | |--------|--------|----------------| | HBsAg | Positive | Active HBV infection (acute or chronic) | | Anti-HBs | Negative | No immunity; not recovered | | Anti-HBc IgM | Positive | **Acute infection** (appears early, disappears in 6 months) | | HBeAg | Positive | High viral replication, high infectivity | | Anti-HBe | Negative | Consistent with early acute phase | **Key Point:** Anti-HBc IgM is the hallmark of acute hepatitis B. Its presence definitively distinguishes acute from chronic infection. ### Diagnostic Algorithm ```mermaid flowchart TD A[HBsAg Positive]:::outcome --> B{Anti-HBc IgM?}:::decision B -->|Positive| C[Acute Hepatitis B]:::action B -->|Negative| D[Chronic Hepatitis B]:::action C --> E[Supportive care, monitor for fulminant failure]:::action D --> E2[Assess for cirrhosis, antiviral therapy]:::action ``` **High-Yield:** The presence of **anti-HBc IgM** is the single most reliable marker to diagnose acute HBV infection. It appears within 1–2 weeks of symptom onset and typically disappears by 6 months. **Clinical Pearl:** HBeAg positivity in acute infection indicates high viral load and infectivity; it usually clears as the patient recovers, followed by appearance of anti-HBe. ### Why This Is Acute, Not Chronic - **Acute presentation:** 2-week history of jaundice and symptoms - **Anti-HBc IgM:** Pathognomonic for acute phase - **Normal INR:** Rules out fulminant hepatic failure (so far) - **Chronic HBV** would show anti-HBc IgG (not IgM) and typically milder transaminitis **Mnemonic:** **ACUTE HBV = Anti-HBc IgM + HBsAg + Clinical symptoms within weeks**