Immunologic studies of anaphylaxis to iron dextran in patients on renal dialysis

Systemic reactions resembling anaphylaxis have occurred after intravenous (IV) iron-dextran administration, a treatment modality that has acquired increased acceptance following the use of erythropoietin for the anemia of patients with chronic renal diseases. Three such patients sustained anaphylactoid reactions immediately after receiving IV test doses of iron-dextran which were their only known exposures. In an effort to determine the mechanism of their reactions, we applied tests for (1) basophil degranulation by iron-dextran, basophil histamine release; (2) a type I anaphylactic reaction, specific IgE antibodies; and (3) an immune complex activation, specific IgG antibodies against iron-dextran. Six other patients with renal diseases served as controls, three of whom had tolerated IV iron-dextran, and three without known exposure. One patient only had any test abnormalities. Her initial positive basophil histamine release and specific IgG antibodies reversed and declined respectively at a 4-month follow-up study. She had developed anaphylaxis, and her studies had been performed at a time after anaphylaxis earlier than the other two. The mechanisms of iron-dextran anaphylaxis may be multiple and not be detectable several months after the incident. Prospective studies will probably be required for a predictive test to be developed.