Clinical features and therapy of acute thallium poisoning

Severe acute thallium poisoning in a young man is described. He presented with transient loss of consciousness and paraesthesiae of finger tips and lips, with a blood thallium concentration of 5750 micrograms/l (levels above 200 micrograms/l are toxic). He rapidly lost limb sensation and power and later required temporary mechanical ventilation and nasogastric feeding. The neurological sequelae one year afterwards are a flaccid paraparesis, cerebellar ataxia and mental impairment. Immediate cardiovascular complications included hypertension, sinus tachycardia, ECG abnormalities and an episode of ventricular fibrillation. We were able to assess the relative merits of different methods advocated for enhancing thallium excretion. Oral Prussian blue, forced diuresis and haemodialysis were found to be the most effective: 2000 mg of thallium were eliminated over 20 days, 820 mg over 46 days and 225 mg over 25 days respectively by these methods. Haemofiltration was ineffective. Diethyldithiocarbamate, a chelating agent, brought about a rise in serum thallium concentration accompanied by clinical deterioration and its use should be abandoned.