Toxin

Thallium Poisoning

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Thallium Poisoning, Thallium Toxicity

  • Background
  1. Thallium is a household Pesticide and rodenticide (banned by EPA in 1972)
  2. Used in semiconductor industry in production of switches and closures
  3. Radiopharmaceutical Agent (e.g. Stress Thallium)
  4. Still available for purchase in U.S.
  5. Has been used to intentionally poison others
  • Mechanism
  1. Thallium is colorless and odorless, and water soluble
  2. Exposure
    1. Ingestion (acute Poisonings)
    2. Skin absorption or inhalation (chronic Poisonings)
  3. Activity
    1. Distributes within the cell in similar fashion to Potassium
    2. Disrupts protein synthesis
    3. Affects heme metabolism
    4. Poisons mitochondria
      1. Inhibits oxidative phosphorylation
      2. Affects Sodium-Potassium ATPase
  4. Half-Life: 2-4 days (Up to 15 days)
  5. Excretion
    1. Renal: 1/3 (esp. in first 24 hours)
    2. Hepatic: 2/3
  • Symptoms
  1. Early findings
    1. Abdominal Pain
    2. Vomiting
    3. Chest Tightness
  2. Later findings
    1. Distal peripheral sensory Neuropathy (Leg Pain)
    2. Ascending weakness
    3. Dysphagia
    4. Eyelid Ptosis
    5. Altered Level of Consciousness
    6. Seizures
  3. Chronic findings
    1. Alopecia
    2. Nail changes (Mees' Lines)
    3. Anemia
  • Labs
  1. Complete Blood Count (CBC) with Platelet Count
    1. Anemia
    2. Thrombocytopenia
  2. Basic Chemistry (Chem8)
    1. Hyponatremia
    2. Hypokalemia
  3. Thallium Levels
    1. Not typically useful in acute management (delayed results)
    2. Obtain sample from urine, blood or hair
    3. Toxicity at blood level >10 mcg/dl (urine level > 20 mcg/dl)
    4. Severe exposure level >30 mcg/dl
  • Management
  1. Electrolyte replacement
    1. Potassium Replacement in Hypokalemia
  2. Thallium Clearance
    1. Maximize hydration to increase renal thallium clearance
    2. Prussian Blue 3 g orally three times daily promotes fecal thallium clearance
    3. Activated Charcoal repeatedly dosed may also increase excretion
    4. Hemodialysis in massive Overdose
  • References
  1. Tomaszewski (2021) Crit Dec Emerg Med 35(1): 28
  2. Leikin (1996) Poisoning and Toxicology, Lexicomp, Cleveland, p. 1026-7