What are key lab findings during the first 3 phases of hepatotoxicity in acetaminophen toxicity/poisoning?

Updated: Jan 17, 2020
  • Author: Susan E Farrell, MD; Chief Editor: Michael A Miller, MD  more...
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Key laboratory findings during the first 3 phases of acetaminophen hepatotoxicity are as follows:

  • Phase 1: Approximately 12 hours after an acute ingestion, liver function studies show a subclinical rise in serum transaminase levels (ie, ALT, AST)

  • Phase 2: Serum studies reveal elevated ALT and AST concentrations, PT, and bilirubin concentration; renal function abnormalities may also be present and indicate nephrotoxicity

  • Phase 3: Severe toxicity is evident on serum studies, and include: lactic acidosis, prolonged PT or INR, markedly elevated ALT and AST (≥10,000 IU/L), elevated total bilirubin level of more than 4 mg/dL (primarily indirect), hypoglycemia, and hyperammonemia are reported; hepatic centrilobular necrosis is diagnosed on liver biopsy

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