Ethyl Mercury Poisoning During a Protein A Immunoadsorption Treatment

We describe the case of a 38-year-old woman with Guillain-Barré syndrome who was accidentally intoxicated with thimerosal, a column disinfectant containing ethyl mercury, during a protein A immunoadsorption treatment. The 1-time overdose caused by an equipment handling error led to a maximum blood serum mercury level of 2,250 μg/L, thus exceeding the normal blood reference range by a factor of approximately 200. Although the patient did not show short- or long-term clinical signs of mercury intoxication, she was treated with chelation therapy, and we replaced thimerosal with a commercially available mercury-free disinfectant, suggesting that thimerosal is no longer indicated for preservation of protein A columns.