Thallium Toxicity Treatment & Management

The prehospital treatment should focus on 4 areas: (1) stabilizing acute life-threatening conditions, (2) initiating supportive therapy, (3) identifying the time and route of exposure, and (4) beginning the decontamination process.

• Establish ABCs.
• Administer oxygen as needed.
• Obtain intravenous access.
• Remove contaminated clothing as soon as possible. Avoid self-exposure and wear protective clothing that is appropriate to the type and degree of contamination. Wear air-purifying or supplied-air respiratory equipment as necessary.
• Activated charcoal should be considered in patients presenting within 1 hour of ingestion and have an intact or protected airway.

The goals of treating a patient with thallium toxicity are initial stabilization, prevention of absorption, enhanced elimination, and antidotal therapy.

• Following the initial assessment and stabilization of the patient, aggressive gastrointestinal decontamination should be instituted. If not performed in the prehospital setting, remove contaminated clothing while avoiding self-exposure. With dermal exposure, thoroughly wash exposed skin with soap and water. For eye exposure, irrigate exposed eyes with copious amounts of room temperature water for at least 15 minutes. Be sure to wear protective clothing appropriate to the type and degree of contamination, and wear air-purifying or supplied-air respiratory equipment as necessary.
• Gastrointestinal decontamination, activated charcoal, and Prussian blue (potassium ferric hexacyanoferrate) are recommended in thallium ingestions.
• Consider orogastric lavage in patients presenting within 1 hour postingestion if they have not vomited or if thallium is observed in the stomach on radiographs in patients who have vomited. In addition, whole-bowel irrigation with polyethylene glycol electrolyte lavage solution may be useful, especially when radiopaque material is visualized on an abdominal radiograph.
• Although both Prussian blue and activated charcoal absorb thallium, it appears that Prussian blue has absorptive superiority. In addition, because it has a far better safety profile than other proposed therapies, Prussian blue should be considered the drug of choice in acute thallium poisoning.^[18]
• Prussian blue is a crystal blue lattice of potassium ferric ferrocyanide. It acts as an ion exchanger for univalent cations, with its affinity increasing as the ionic radius of the cation increases. Prussian blue exchanges potassium ions from its lattice with thallium ions in the gut lumen. Removal of thallium from the gut creates a concentration gradient causing an increase in thallium exchange into the gut lumen. This interrupts its enterohepatic recirculation and increases its elimination. Prussian blue releases a negligible amount of cyanide (< 1.6 mg, minimal lethal dose of cyanide in humans is approximately 50 mg) and does not present a safety concern following its use.^[19]
• Prussian blue (Radiogardase) was approved by the Food and Drug Administration (FDA) in 2003 but is still difficult to obtain for pharmaceutical use in the United States. However, it has been obtained from The Oak Ridge Institute for Science and Education and the Radiation Emergency Assistance Center (REAC) in Oak Ridge, Tennessee. In addition, successful therapy using the laboratory reagent of Prussian blue has been documented in the United States.^{[18, 20]}
• In patients in whom Prussian blue cannot be obtained and thallium poisoning is suspected, multidose activated charcoal may be effective. Because thallium undergoes enterohepatic and enteroenteric recirculation, repeated charcoal administration (0.25-0.5 g/kg q2-4h) may enhance fecal elimination.
• Forced diuresis with potassium loading was previously recommended to increase the renal clearance of thallium, but this may exacerbate the neurologic and cardiovascular symptoms and is no longer advised.
• Chelating agents such as EDTA, dimercaprol, and D-penicillamine have not been shown to be effective and should be avoided.
• The usefulness of hemodialysis and hemoperfusion is controversial, but they may be useful during early thallium poisoning before extensive distribution within the body tissues has occurred.^[21]
• N -acetylcysteine and l-cysteine have not been shown to be effective in reducing mortality in animal models.

• Consultation with a regional poison control center or medical toxicologist may be of benefit.