Arsenic Encephalopathy Associated with Excessive Seafood Consumption: A Case Report

Arsenic toxicity is an uncommon and frequently underrecognized cause of subacute encephalopathy. Diagnosis requires careful integration of exposure history, clinical findings, and laboratory testing, particularly because dietary sources such as seafood can elevate urinary arsenic levels without causing true toxicity. We report the case of a 39-year-old woman presenting with progressive cognitive impairment and functional decline who was found to have markedly elevated urinary arsenic levels in the setting of excessive seaweed consumption. Extensive evaluation for infectious, autoimmune, metabolic, and structural causes of altered mental status was unrevealing. Her cognitive function steadily improved with supportive care and elimination of dietary exposure, without chelation therapy. This case highlights the diagnostic challenges in interpreting elevated urinary arsenic levels, the contribution of seafood to total arsenic measurements, and the critical role of arsenic speciation in clinical interpretation and management.