Hypersensitivity reactions to iron products: 10-year experience in a Portuguese tertiary Centre

Abstract

To the Editor, Iron products (IP) have been increasingly used in recent years and constitute the firstline treatment for iron deficiency anemia (1). Although hypersensitivity reactions (HSR) to IP are rare and the risk of anaphylaxis with the currently available iron formulations has been shown to be significantly lower compared to iron dextran (2,13-15), there is still a concern regarding the safety of these products, with cases of fatal outcome reported in the literature (2,3). Here, we evaluate the safety of controlled readministration of IP in patients with previous hypersensitivity reactions to these drugs.We performed a retrospective review of patients referred to the Immunoallergology Department in a tertiary hospital for suspected HSR to IP, from 2011 to 2021. The demographic and clinical characterization of a total of 18 patients (mean age 45.6±14.3 years) is summarized in Table I. We observed a higher prevalence of female patients (83%), likely due to the higher frequency of treatment with IP among women (1).Regarding relevant past medical history, six patients (33%) reported previous reaction(s) to non-IP drugs, a similar prevalence found by Steveling-Klein et al. in a group of 22 adult patients out of 59 (37%) (4). Three patients were atopic (16%) and two presented with inflammatory diseases (sarcoidosis and inflammatory bowel disease; 11%). Interestingly, only 67% reported previous exposure to IP (Table I).The IP most frequently involved in hypersensitivity reactions was ferric carboxymaltose (FCM) in 12 patients (63%), followed by oral non-specified iron formulation in four patients (21%) and iron sucrose (IS) in three (16%). One patient presented HSR to both FCM and IS. The severity of reactions was categorized according to the Ring and Messmer Grading Scale for anaphylactic reactions. The majority of the reactions were classified as grade I (n=11, 58%). Grade II occurred in two HSR (11%) and grade III in five (26%), comparable to the distribution reported in the literature (4).