Acute acetaminophen toxicity

Pathophysiology

• Depletion of intrahepatic glutathione → accumulation of NAPQI (toxic metabolite of acetaminophen)

Clinical features
(time from ingestion)

• ≤24 hr
  • Asymptomatic or nonspecific symptoms (eg, nausea, vomiting, fatigue)
• 24-72 hr
  •  ↑ AST, ALT
• 72-96 hr
  • AST/ALT levels peak (sometimes >10,000 U/L)
  • Severe cases:  ↑ PT/PTT, hypoglycemia, lactic acidosis, ↑ bilirubin, acute kidney injury
• 4-14 days
  • Recovery

Diagnosis

• Serum acetaminophen level (4-24 hr)
• Liver function tests, BUN/creatinine, electrolytes

Treatment

• Activated charcoal (if <4 hr)
• N-acetylcysteine

ALT = alanine aminotransferase; AST = aspartate aminotransferase; BUN = blood urea nitrogen; NAPQI = N-acetyl-p-benzoquinone imine.