PARACETAMOL OVERDOSE

Adapted from GlaxoSmithKline, Guidelines for the management of paracetamol overdose in Adults

ASSESSMENT

• May be asymptomatic/normal LFTs 72-96 hrs post ingestion
• Psychiatric assessment is important

CLINICAL ASSESSMENT

Remember to question witnesses, pre-hospital providers etc. if patient is unreliable

• Time of ingestion
• Slow release formulation
• Amount of ingestion
• Special risk groups
  • Malnutrition
  • HIV infection
  • Chronic ethanol abuse
  • Anticonvulsant use (phenytoin, carbamazepine, phenobarbitone, primidone)
  • Rifampicin

INITIAL INVESTIGATIONS

Paracetamol level is most important investigation with selective indications for other tests

Paracetamol level (taken immediately in unknown-time ingestion or at least 4 hrs post-ingestion)

(click here to go to Rumack Diagram to interpret paracetamol level)

LFTs (if ingestion > 15 hrs ago or chronic ingestion > 150mg/kg/24hrs )

ALT > 1000 IU/L = Severe liver damage
May not rise until 72-96 hrs post ingestion

Creatinine (if ingestion > 15 hrs ago, abnormal LFTs or symptomatic)

Acute tubular necrosis (rarely)

INR (if elevated LFTs or signs of hepatic failure)

BSL (if signs of hepatic failure)

ABG  (if ingestion > 24 hrs ago, abnormal LFTs or symptomatic)

Serial paracetamol level

Indication

• Co-ingestion with codeine/dextropropoxyphene
• Slow Release ingestion
• Borderline 4 hr Paracetamol level

Method

• Take 2-4 hours apart
• Slope of line flatter than nomogram line = Prolonged metabolism (Half-life > 4hrs) = Toxicity