A 42-year-old man from rural Maharashtra presents with a 10-day history of jaundice, dark urine, and pale stools. He reports fever and right upper quadrant pain. On examination, he is icteric, temperature 38.5°C, and has hepatomegaly with tenderness. Laboratory investigations show: total bilirubin 8.2 mg/dL (direct 6.8 mg/dL), ALT 1240 U/L, AST 980 U/L, ALP 240 U/L, PT-INR 1.2. Abdominal ultrasound shows no ductal dilatation, normal gallbladder, and a heterogeneous liver echotexture. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Acute Viral Hepatitis ### Key Diagnostic Features **Key Point:** The clinical and biochemical picture is classic for acute hepatitis: - Marked transaminitis (ALT > AST, both >1000 U/L) with relatively mild ALP elevation - Direct hyperbilirubinemia with dark urine and pale stools (cholestasis phase) - Fever, RUQ pain, and hepatomegaly (hepatic inflammation) - **Absence of biliary ductal dilatation on ultrasound** — rules out mechanical obstruction - Normal PT-INR (preserved synthetic function despite jaundice) ### Why This Is Hepatocellular Jaundice The pattern of **ALT >> ALP** (transaminitis-predominant) with **no ductal dilatation** localizes the lesion to the hepatocyte itself, not the biliary tree. This is the hallmark of acute hepatitis (viral, autoimmune, drug-induced, or alcoholic). ### Differential Reasoning | Feature | Acute Viral Hepatitis | Choledocholithiasis | Biliary Cirrhosis | Pancreatic Cancer | |---------|----------------------|-------------------|------------------|------------------| | **ALT vs ALP** | ALT >> ALP | ALP >> ALT | ALP >> ALT | ALP >> ALT | | **Ductal dilatation** | Absent | Present (CBD >6 mm) | Present | Present | | **PT-INR** | Normal/mild ↑ | Normal | Elevated (cirrhosis) | Normal | | **Fever** | Common | Yes (if cholangitis) | No | No | | **Acute onset** | Yes (days–weeks) | Acute/colicky | Insidious (months) | Insidious | **Clinical Pearl:** In acute hepatitis, the liver is inflamed but the biliary tree is patent — hence no ductal dilatation. The direct hyperbilirubinemia reflects hepatocellular injury with impaired excretion, not obstruction. **High-Yield:** The **ALT:ALP ratio** is a rapid discriminator: - **Hepatocellular pattern** (ALT >> ALP): viral/autoimmune hepatitis, cirrhosis, drug-induced liver injury - **Cholestatic pattern** (ALP >> ALT): obstruction, PBC, PSC, pregnancy-related cholestasis ### Next Steps in Management 1. Serological testing: HAV IgM, HBsAg, anti-HCV, anti-HEV (endemic in rural India) 2. Prothrombin time trend (prognostic marker) 3. Supportive care; monitor for fulminant hepatic failure 4. Avoid hepatotoxic drugs [cite:Harrison 21e Ch 297]