A 28-year-old woman presents with jaundice, dark urine, and pale stools. Investigations show total bilirubin 9.5 mg/dL (conjugated 7.8 mg/dL), AST 380 U/L, ALT 420 U/L, alkaline phosphatase 110 U/L, and INR 1.8. Abdominal ultrasound shows no ductal dilatation. Which of the following is NOT consistent with a diagnosis of acute viral hepatitis?

Explanation

## Acute Viral Hepatitis: Laboratory Pattern Recognition ### Characteristic Laboratory Profile of Acute Viral Hepatitis **Key Point:** Acute viral hepatitis produces a **hepatocellular pattern** of liver injury, characterized by: - Marked elevation of transaminases (often >1000 U/L) - ALT > AST (unlike alcoholic hepatitis) - Relatively mild elevation of alkaline phosphatase - Conjugated hyperbilirubinaemia (due to hepatocellular necrosis and cholestasis) ### Why Disproportionate ALP Elevation is NOT Consistent **High-Yield:** The **ALP-to-transaminase ratio** distinguishes hepatocellular from cholestatic/obstructive patterns: | Pattern | AST/ALT | ALP vs Transaminases | Typical Causes | |---------|---------|----------------------|----------------| | **Hepatocellular** | ALT > AST | ALP mildly ↑ | Viral hepatitis, alcoholic hepatitis, autoimmune | | **Cholestatic/Obstructive** | Variable | ALP >> transaminases | Biliary obstruction, PBC, drug-induced cholestasis | In acute viral hepatitis, alkaline phosphatase is **relatively preserved** despite marked transaminitis. A disproportionate elevation of ALP (>4× the upper limit of normal with transaminases only 2–3× elevated) suggests **cholestasis or biliary obstruction**, not acute hepatitis. **Clinical Pearl:** The patient's ultrasound shows **no ductal dilatation**, ruling out post-hepatic obstruction. The pattern of marked transaminitis with preserved ALP and conjugated hyperbilirubinaemia is classic for acute hepatitis, not cholestasis. ### Why the Other Options Are Correct | Feature | Explanation | |---------|-------------| | **ALT > AST** | Viral hepatitis causes acute hepatocyte necrosis preferentially affecting ALT (more specific for liver). Alcoholic hepatitis shows AST > ALT. | | **Preserved ALP with marked transaminitis** | Hallmark of hepatocellular injury. ALP may rise 2–3×, but transaminases rise 10–100×. | | **Conjugated hyperbilirubinaemia + bilirubinuria** | Hepatocellular necrosis impairs excretion of already-conjugated bilirubin, causing cholestasis. Conjugated bilirubin is water-soluble and filters into urine. | ### Mnemonic: **HALT** for Hepatocellular Pattern - **H**igh transaminases (>1000 U/L) - **A**LT > AST - **L**ow ALP relative to transaminases - **T**ransaminitis >> cholestasis **Tip:** When you see marked transaminitis with mild ALP elevation and no ductal dilatation → think **hepatocellular** (viral, autoimmune, alcoholic). When ALP is disproportionately high → think **cholestatic** (obstruction, PBC, drug-induced).