A 19-year-old woman ingests an unknown number of paracetamol tablets in a suicide attempt. She arrives at the emergency department 4 hours after ingestion and appears well. Serum paracetamol concentration plots above the treatment line on the Rumack-Matthew nomogram. What is the correct action?

• A Discharge home since she is asymptomatic
• B Start intravenous N-acetylcysteine ✓
• C Give activated charcoal and observe for 24 hours
• D Repeat the level at 24 hours before deciding

Explanation

A 4-hour level above the treatment line on the Rumack-Matthew nomogram predicts hepatotoxicity and mandates immediate N-acetylcysteine, which replenishes glutathione and detoxifies NAPQI. It is most effective when started within 8 hours, so waiting for a repeat level sacrifices the therapeutic window. Asymptomatic patients are unreliable guides because clinical jaundice and right upper quadrant pain appear only after 24 to 72 hours, once injury is established.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.