Acute thallium poisoning: clinical features, toxicokinetics and one-year neurological outcomes

INTRODUCTION: Thallium poisoning is a rare but highly toxic heavy metal intoxication associated with peripheral neuropathy. However, longitudinal data integrating toxicokinetic profiles with electrophysiological outcomes remain limited. METHODS: Five patients with confirmed acute thallium poisoning were evaluated. Clinical symptoms, laboratory results, dynamic serum and urinary thallium concentrations, and electrophysiological results were recorded. All patients underwent electrophysiological follow-up one year later. Thallium elimination kinetics were analyzed using nonlinear regression. RESULTS: All patients developed peripheral neuropathy. Sensory symptoms generally preceded the onset of alopecia. During treatment, dynamic monitoring showed a progressive decrease in thallium concentrations. Toxicokinetic analysis suggested an approximate first-order elimination pattern, with an estimated serum half-life ranging from 3.8 to 5.7 days. Electrophysiological studies revealed distal axonal neuropathy characterized by reduced compound muscle action potential amplitudes. At one-year follow-up, residual axonal involvement persisted in some patients. DISCUSSION: Peripheral neuropathic symptoms may serve as an early clinical indicator of thallium poisoning. Persistent electrophysiological abnormalities despite declining thallium levels suggest incomplete neurological recovery. CONCLUSIONS: Dynamic monitoring of thallium levels can help evaluate elimination kinetics during detoxification therapy. Persistent axonal injury suggests that thallium-induced neuropathy may result in long-term neurological sequelae, highlighting the importance of early diagnosis and long-term electrophysiological monitoring.