Consider GI decontamination for unknown ingestion time.

Only indicated for single, acute ingestion occurring 24 hr after ingestion.

AST levels > 1000 IU/L are more likely to result from acetaminophen poisoning than from chronic hepatitis or alcoholic liver disease.

AST and ALT elevation more specific than GGT and alkaline phosphatase.

Metabolic acidosis seen with extremely large ingestion.

Obtaining multiple levels is rarely indicated in the absence of hepatotoxicity.

Obtaining level between 2-4 hrs post ingestion is helpful if level is undetectable (essentially zero risk of progressing to toxic levels), but anything other than undetectable requires a repeat draw at 4 hrs.

Obtain 4 hrs post-ingestion and compare level to Rumack-Matthew nomogram.

Rumack-Matthew Nomogram (use correct units!) Work-Up

Acetaminophen toxicity (most common cause of acute liver failure in the US ).

Deterioration to multi-organ failure and death ORĭifferential Diagnosis Causes of acute hepatitis.

Clinical improvement and recovery (7-8 d) OR.

Acute renal failure (1-2% usually after hepatic failure is evident).

Encephalopathy (esp with massive ingestions).

Massive Ingestion (>500 mg/kg) may present with acidemia, coma, hemodynamic changes shortly after ingestion and prior to hepatic necrosis.

Hypokalemia (associated with high 4-hr level).

NAC increases availability of glutathione.

In overdose, glutathione runs out, NAPQI accumulates → liver injury.

APAP toxic metabolite NAPQI usually quickly detoxified by glutathione stores in liver.

This process becomes overwhelmed in overdose and metabolism is shifted to the CYP 450 pathway generating toxic NAPQI.

Acetaminophen is metabolized by sulfation and glucuronide conjugation.

E - Conjugated and unconjugated excreted through kidneys.

5-10% - Metabolism through CYP450/CYP2E1 (Forms NAPQI).

Antipyresis through inhibition of hypothalamic heat center.

Possibly through inhibition of Cyclooxygenase-3 (COX-3).

Initial loading dose of NAC is 150 mg/kg IV (140 mg/kg PO).

Give NAC if level is >150 mcg/mL four hours post-ingestion.

200 mg/kg in healthy children 1-6 years of age.

>6 g or >150 mg/kg per 24hr period x 2days.

>10 g or >200 mg/kg as single ingestion or over 24hr period OR.

Now the most common cause of acute liver failure in the US.

Includes Tylenol and numerous brands and products including acetaminophen.

2.4 Stage 4 (after day 5, up to 2 weeks).

Antidote for acetaminophen toxicity