Monday November 28, 2005
Four Phases of Acetaminophen Toxicity And Rumack-Matthew Nomogram (revised).

Acetaminophen (Tylenol, Paracetamol) toxicity is divided into four phases time-wise.

Phase 1 (up to 24 hours): Mild symptoms

Phase 2 (24- 48 hours): Right upper quadrant pain and rising Liver enzymes with deteriorating symptoms.

Phase 3 (48-96 hours): Liver failure

Phase 4 (4 days to 3 weeks): Resolution or death.

Clinical Significance: Patient’s Acetaminophen level should be plotted on Rumack-Matthew nomogram (revised) during first 24 hours of ingestion and if it falls in "possible" or "probable" liver failure risk area of nomogram, hepatology team should be alerted (or transfer to tertiary care center with liver services) as clinical deterioration may unfold very quickly.

Rumack-Matthew nomogram (revised) is available in the reference article below.

References: click to get abstract/article
1. Acetaminophen Intoxication and Length of Treatment: How Long Is Long Enough? - Pharmacotherapy 23(8):1052-1059, 2003 (available via medscape.com with free registration).