Amanita Species Mushroom Poisoning

Aka: Amanita Species Mushroom Poisoning, Amatoxin, Amatoxin Mushroom Toxicity, Amanitin, Death Cap Mushroom, Amanita Phalloides, Destroying Angel Mushroom, Amanita Bisporigera

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II. Pathophysiology: Amatoxin - Amanitins (alpha, beta)

  1. Amanitins are Amatoxins (subset of Mycotoxins) found in various mushroom species
    1. Amanita (A. bisporigera, A. phalloides)
    2. Galerina (G. marginata)
    3. Lepiota (L. brunneoincarnata)
  2. Amanitins are cyclic octapeptides contained in carpophores (narrow stalks leading to fungal fruiting bodies)
    1. Potent RNA Polymerase inhibitors (blocks mRNA and Protein synthesis)
    2. Amanitin 0.1 mg/kg is a potentially lethal dose
      1. Some mushrooms may contain 0.2-0.4 mg a-Amanitin per dry weight mushroom (25-50 g per mushroom)

III. Pharmacokinetics: Amatoxin

  1. Rapid gastrointestinal absorption
  2. Hepatic uptake with bile salts and organic anions (via transport Proteins OATP1B3, NTCP)
  3. Excretion
    1. Renal excretion in the urine
    2. Bile excretion (but significant enterohepatic recirculation)

IV. Causes

  1. Amatoxins (esp. alpha-Amanitin)
    1. Death Cap (Amanita Phalloides)
    2. Destroying Angels (Amanita Bisporigera, Amanita ocreata, Amanita virosa)
  2. Isoxazole (muscimol and ibotenic acid)
    1. Amanita muscaria (Fly Agaric)
    2. Hallucinogenic mushrooms without renal and hepatic toxicity (not covered on this page)

V. Findings: Amatoxin

  1. Onset of intial symptoms (gastrointestinal) delayed 5-24 hours after ingestion
  2. Gastrointestinal
    1. Nausea or Vomiting
    2. Abdominal Pain
    3. Diarrhea
  3. Liver
    1. Increased AST and ALT
    2. Coagulopathy
    3. Hyperbilirubinemia
    4. Hepatic necrosis
  4. Renal
    1. Acute Kidney Injury
  5. Neurologic
    1. Hepatic Encephalopathy
    2. Altered Level of Consciousness to coma
    3. Seizures
    4. Peripheral Neuropathy (sensory and motor)
  6. Endocrine
    1. Hypoglycemia
    2. Thyroid Hormone levels (T4 and T3) decreased
    3. Serum Calcium Decreased and Parathyroid Hormone and Calcitonin levels increased
    4. Insulin and C-Peptide levels increased

VI. Labs: Suspected Amatoxin Poisoning

  1. See Unknown Ingestion
  2. Complete Blood Count (CBC)
  3. Comprehensive metabolic panel (including renal and Liver Function Tests, Electrolytes, Glucose, Calcium)
  4. Serum Lactic Acid
  5. Coagulation studies (INR and PTT)
  6. Thyroid Stimulating Hormone (TSH)
  7. Free Thyroxine Level (Free T4)
  8. Alpha-Amanitin serum or urine levels (limited availability)

VII. Management: Amatoxin Poisoning

  1. Gastric Decontamination (Activated Charcoal)
  2. Supportive care
    1. Antiemetics
    2. Intravenous Fluids with dextrose
    3. Replace Electrolytes
    4. Admission for serial lab testing in suspected ingestions
  3. Enhanced elimination (extracorporeal removal)
    1. Strongly consider in early presentation in first 12 to 24 hours
    2. Hemodialysis or Hemoperfusion
  4. Hepatic uptake inhibitors of Amanitin
    1. Penicillin G infusion (500,000 IU/kg/day)
    2. Methylprednisolone
    3. Silibinin (Silybin)
      1. Active ingredient in Silymarin, extracted from seeds of Milk Thistle (Silybum marianum)
      2. Strongly consider in early presentations
  5. Other agents to consider
    1. Polymyxin B (starting at 2.5 mg/kg IV)
      1. Displaces alpha-Amanitin from RNA Polymerase II
    2. N-Acetylcysteine (NAC)
      1. Hepatoprotection
  6. Acute Liver Failure
    1. ICU admission
    2. Transfer to tertiary center if transplant candidate

VIII. Prognosis: Factors Associated with Poor Outcomes in Amatoxin Poisoning

  1. Hypotension
  2. Mucosal Hemorrhage
  3. Uremia
  4. Thrombocytopenia

IX. Resources

  1. Amatoxin Mushroom Toxicity
    1. https://www.ncbi.nlm.nih.gov/books/NBK431052/

X. References

  1. Carroll and Yakey (2026) Crit Dec Emerg Med 40(9): 36

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