A 28-year-old man from Delhi presents with jaundice, dark urine, and abdominal discomfort for 10 days. He reports eating raw shellfish at a street vendor 4 weeks ago. On examination, he is afebrile, icteric, with hepatomegaly but no ascites. Laboratory findings: total bilirubin 8.2 mg/dL (direct 6.1 mg/dL), ALT 2840 IU/L, AST 2100 IU/L, ALP 180 IU/L, albumin 3.8 g/dL, INR 1.1. Anti-HAV IgM is positive; anti-HBc, anti-HCV are negative. Abdominal ultrasound shows no cirrhotic features. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Acute Hepatitis A ### Key Clinical Features **Key Point:** The diagnosis of acute hepatitis A is established by the combination of: - Acute onset jaundice and dark urine (conjugated hyperbilirubinemia) - Marked transaminitis (ALT > AST, typical of acute viral hepatitis) - **Positive anti-HAV IgM** — the gold standard marker for acute HAV infection - Preserved synthetic function (normal INR, albumin 3.8 g/dL) - Negative serologies for HBV and HCV ### Epidemiological Context **Clinical Pearl:** The 4-week incubation period and consumption of raw shellfish are classic for hepatitis A transmission. HAV is transmitted via the fecal-oral route and commonly contaminates shellfish in areas with poor sanitation. ### Laboratory Interpretation | Parameter | Finding | Significance | |-----------|---------|---------------| | Anti-HAV IgM | **Positive** | Diagnostic of acute HAV; appears at symptom onset | | ALT | 2840 IU/L | Marked elevation typical of acute viral hepatitis | | ALT > AST | Yes | Pattern favors viral over alcoholic hepatitis | | INR | 1.1 (normal) | Preserved hepatic synthetic function | | Albumin | 3.8 g/dL | Normal; rules out chronic liver disease | | Anti-HBc, Anti-HCV | Negative | Excludes HBV and HCV | ### Natural History **High-Yield:** Acute hepatitis A: - Has a self-limited course in immunocompetent adults - Does NOT progress to chronic infection - Resolves completely within 6–12 weeks in most cases - Confers lifelong immunity ### Management Approach Supportive care with monitoring of INR and bilirubin. No specific antiviral therapy is indicated. Prognosis is excellent in this patient given normal synthetic function. [cite:Harrison 21e Ch 297]