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Use of intravenous iron after an infusion reaction

Published online: April 1, 2021

When oral formulations of iron are not tolerated, deemed inadequate or both, intravenous administration of iron is the mainstay of treatment of iron deficiency anemia. A history of reaction to intravenous iron has previously been reported to be a risk factor for future reactions to intravenous iron, and some guidelines have suggested that a severe reaction should prohibit further use. Evidence regarding the basis for these recommendations is limited to expert opinion and isolated case reports. It is believed that the majority of reactions to intravenous iron are not an immunological allergy-mediated response, however the underlying mechanisms are not easy to distinguish clinically.

In a recent article in The Journal of Allergy and Clinical Immunology: In Practice, Stojanovic et al. report the results of a retrospective cohort study exploring the feasibility and safety of administering intravenous iron following an adverse reaction to an initial iron infusion. They examined 13,509 iron infusions administered at their tertiary academic center and 2 nearby secondary centers over a ten-year period. Inclusion criteria included all reported adverse reactions, occurring during or after an intravenous iron infusion. One hundred ninety-five initial reactions were classified into 5 groups; those occurring during the infusion stratified by severity, and reactions occurring post completion of the infusion. A known clinical syndrome associated with intravenous iron characterized by flushing and truncal muscle aches was considered separately. Following an initial adverse reaction to intravenous iron, the outcomes of recommencement and completion of the index infusion (n=33) or later rechallenge to the same or a different intravenous iron formulation on a subsequent occasion (n=71) were separately presented.

Stojanovic and colleagues reported that where a clinical need for iron replacement persists following a reaction to intravenous iron, recommencement of the initial infusion after transient flushing and truncal muscle aches or other reactions of mild or moderate severity was safe. When recommencing an infusion, a reduced infusion rate and pre medication may facilitate completion. Findings also suggested that rechallenge to an alternative intravenous iron formulation was safe following initial reactions to intravenous iron characterized by transient flushing and truncal muscle aches or mild to moderate reactions involving only 1 organ system. All patients (n=9) rechallenged to the same iron formulation after an initial mild or single-system moderate reaction tolerated rechallenge. All patients (9/9) were able to tolerate rechallenge to an alternative formulation following an initial moderate multi-system or severe reaction. Use of a slow infusion protocol did not appear critical for successful re-challenge.

Overall, these findings demonstrate safety of both recommencement of the initial infusion and rechallenge in appropriate patient groups after an adverse reaction to intravenous iron. Globally, where alternative intravenous iron formulations are not available, it may be reasonable to consider rechallenge to the same formulation.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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