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