thallium poisoning

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Epidemiology

used in the manufacture of electronic components optical lenses, semiconductor materials, alloys, gamma radiation detection equipment, imitation jewelry, artist's paints, low temperature thermometers, & green firework
trace amounts of Tl-201 are used in myocardial perfusion & viability scintigraphy
thallium exposure may occur at smelters in the maintenance & cleaning of ducts & flues
contamination of cocaine, heroin, & herbal products

can be absorbed through the skin, ingested or inhaled
ingestion of 1 gram or 8 mg/kg is toxic
Tl+ mimicks K+ but additionally binds thiols
riboflavin sequestration
inhibits pyruvate kinase & succinate dehydrogenase
- impaired glucose metabolism
- disruption of the Kreb cycle
ribosomal inhibition
myelin sheath injury

nausea, vomiting, & diarrhea within 48 hours of exposure
within a few days, pain, headaches, peripheral neuropathy
alopecia
- most common & classic manifestation of thallium toxicity
- occurs 7-12 days after the initial onset of symptoms
- after 2-3 weeks alopecia occurs
Mees lines appear within 2-4 weeks
painful ascending peripheral neuropathy
- paresthesia, numbness, loss of reflexes, muscle wasting, dysarthria, blurred vision, ataxia, memory impairment, psychosis, seizures, coma can occur

electrocardiogram may show tachyarrhythmia
nerve conduction studies
- axonal sensorimotor peripheral neuropathy
- nerves innervating the feet most affected
electromyography^[4]
electroencephlogram may show nonspecific slow-wave activity in severe cases
electroretinogram
- delayed visual evoked response
- changes tend to occur before clinical symptoms Radiography:
abdominal radiograph may reveal thallium metal after ingestion (thallium is radiopaque)

ABCs
oxygen as necessary
intravenous access
remove contaminated clothing as soon as possible
- avoid self-exposure & wear protective clothing appropriate to the type & degree of contamination
- wear air-purifying or supplied-air respiratory equipment as necessary
goals
- initial stabilization
- prevention of absorption
- enhanced elimination
- antidotal therapy
activated charcoal should be considered in patients presenting within 1 hour of ingestion with an intact or protected airway
whole-bowel irrigation with polyethylene glycol electrolyte lavage solution may be useful
potassium ferrihexacyanoferrate (Prussian blue, Radiogardase)
hemodialysis may be useful early prior to tissue distribution