Key Points
- Use the highest‑yield diagnostic test early; do not let testing delay time‑critical therapy.
- Set objective targets (hemodynamic, neurologic, respiratory) and reassess frequently.
- Plan definitive source control or disease‑specific therapy when indicated; document follow‑up and patient education.
Algorithm
- Obtain 4‑h level for known single ingestions; if time unknown or staggered, start NAC immediately.
- Use Rumack‑Matthew nomogram to decide treatment for acute single ingestions.
- Prefer IV NAC in severe toxicity, late presenters, pregnancy, or inability to tolerate PO.
- Monitor AST/ALT/INR and mental status; extend NAC until clinical and biochemical recovery.
- Apply ALF transplant criteria (e.g., King’s College) and consult a transplant center if indicated.
Clinical Synopsis & Reasoning
For single acute ingestions, use the Rumack‑Matthew nomogram (≥4 h level) to guide treatment; for staggered or unknown ingestions, start NAC immediately. Prefer IV NAC for severe toxicity, late presenters, or vomiting; monitor LFTs/INR and apply transplant criteria when ALF develops.
Treatment Strategy & Disposition
Stabilize ABCs. Initiate guideline‑concordant first‑line therapy with precise dosing and continuous monitoring. Escalate to advanced/procedural interventions based on explicit failure criteria. Define ICU, step‑down, and ward disposition triggers; involve specialty teams early.
Epidemiology / Risk Factors
- Risk varies by comorbidity and precipitants; see citations for condition‑specific data.
Investigations
| Test | Role / Rationale | Typical Findings | Notes |
|---|---|---|---|
| Serum acetaminophen level at ≥4 h | Risk stratification | Above treatment line → treat | Repeat if unknown time |
| AST/ALT, INR, bilirubin | Hepatic injury | Rising values suggest toxicity | Trend frequently |
| Pregnancy test (all females of childbearing age) | Safety | — | — |
Pharmacology
| Medication/Intervention | Mechanism | Onset | Role in Therapy | Limitations |
|---|---|---|---|---|
| N‑acetylcysteine IV 150 mg/kg load → 50 mg/kg over 4 h → 100 mg/kg over 16 h (extend if needed) | Antidote | Hours | Glutathione repletion; prevents hepatotoxicity | Adjust by levels/clinical status |
| Oral NAC 140 mg/kg load → 70 mg/kg q4h x17 | Antidote | Hours | Alternative when IV not feasible | GI intolerance |
| Antiemetics (ondansetron) | Supportive | Minutes | Facilitate oral NAC | QT risk |
Prognosis / Complications
- Outcome depends on timeliness of diagnosis and definitive therapy; monitor for complications.
Patient Education / Counseling
- Provide red‑flag education, adherence guidance, and explicit return precautions; arrange timely specialty follow‑up.
References
- TOXNET/Goldfrank reviews; AASLD guidance on acetaminophen toxicity — Link
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