A 32-year-old man from rural Maharashtra presents with a 2-week history of jaundice, dark urine, and pale stools. He reports consuming contaminated water from a local well 4 weeks ago. On examination, he is afebrile, icteric, with mild hepatomegaly and right upper quadrant tenderness. Laboratory findings show: Total bilirubin 8.2 mg/dL (direct 6.1 mg/dL), AST 1240 IU/L, ALT 1680 IU/L, ALP 180 IU/L, PT-INR 1.1, albumin 3.8 g/dL. Serological testing shows anti-HAV IgM positive, anti-HAV IgG negative, HBsAg negative, anti-HCV negative. What is the most likely diagnosis?

Explanation

## Diagnosis: Acute Hepatitis A ### Clinical Presentation **Key Point:** The combination of acute jaundice, dark urine, pale stools, and a clear exposure history to contaminated water is classic for acute hepatitis A. ### Serological Interpretation | Marker | Result | Interpretation | |--------|--------|----------------| | Anti-HAV IgM | Positive | Acute infection (diagnostic) | | Anti-HAV IgG | Negative | No past immunity | | HBsAg | Negative | No hepatitis B | | Anti-HCV | Negative | No hepatitis C | **High-Yield:** Anti-HAV IgM is the diagnostic marker for acute hepatitis A. It appears at symptom onset and persists for 3–6 months. Anti-HAV IgG appears later and indicates past infection or immunity. ### Laboratory Pattern **Key Point:** The markedly elevated transaminases (ALT > AST, both >1000 IU/L) with relatively preserved synthetic function (normal PT-INR, near-normal albumin) is typical of acute viral hepatitis. ### Epidemiology & Risk Factors **Clinical Pearl:** Hepatitis A is transmitted via the fecal-oral route. Contaminated water is a common source in endemic areas like rural India. The incubation period is 15–50 days (median 28–30 days), consistent with his 4-week exposure-to-symptom timeline. **Mnemonic: HAV Characteristics — FECAL** - **F**ecal-oral transmission - **E**ndemic in developing countries - **C**hildhood infection common - **A**cute illness (no chronic carrier state) - **L**iver inflammation (self-limited) ### Prognosis **Key Point:** Hepatitis A is self-limited in immunocompetent hosts. Fulminant hepatic failure occurs in <1% of cases. No chronic infection develops. ### Management **High-Yield:** Supportive care is the mainstay. Monitor PT-INR and mental status for signs of encephalopathy. Vaccination (inactivated HAV vaccine) is recommended for contacts and post-recovery.