D1.28 - Clinical Follow-up in Radiocontrast Media–Induced Hypersensitivity Reactions: Beyond the Reaction

Radiocontrast media (RCM) are widely used in diagnostic and therapeutic procedures. Hypersensitivity reactions related to RCM have become more frequent due to the increasing use of these agents. This study aimed to present real-life data by evaluating the clinical characteristics of patients who presented to our clinic with a history of RCM-induced hypersensitivity reactions, the diagnostic testing processes, and their experiences with subsequent RCM exposures after completion of the diagnostic work-up.

A total of 29 patients who presented to the Ege University Faculty of Medicine, Department of Internal Medicine, Division of Allergy and Immunology with a history of RCM-induced hypersensitivity reactions between January 2019 and May 2025 were included in the study. Sociodemographic characteristics, selected biochemical parameters, reaction features, and skin test results were retrospectively recorded. Subsequently, patients were re-contacted to assess re-exposure to RCM and the occurrence of any reactions.

The mean age of the study population was 59.9 ± 10.7 years, and 75.9% were female. The most common comorbidities were hypertension (62.1%), cardiovascular disease (44.8%), and diabetes mellitus (31%). The most frequent allergic conditions were a history of drug allergy (48.3%), allergic rhinitis (34.5%), and asthma (27.6%). Of the adverse drug reactions (ADRs), 82.8% were immediate-onset. According to the Brown classification, ADR severity was Grade I in 29.2%, Grade II in 25%, and Grade III in 45.8% of cases. Anaphylaxis occurred in 54.2% of patients. Baseline serum tryptase levels were significantly higher in patients who experienced Grade III ADRs (7.75 ± 0.69 µg/L) compared with those with Grade I–II reactions (p = 0.02). Iodinated contrast media (ICM) were responsible in 75.9% of cases, while gadolinium-based contrast media (GBCM) accounted for 24.1%. The most frequently implicated ICM was iohexol (27.3%), and the most common GBCM was gadobutrol (28.6%). Most patients (74.1%) had no prior exposure to contrast media. The mean interval between the reaction and diagnostic testing was 109.5 ± 87.1 months. Skin testing was performed with the suspected agent in 13.8% and with an alternative agent in 55.1% of patients; all skin test results were negative. During follow-up, 28 patients were contacted; 14 underwent repeat imaging with contrast media. Of these, 9 received premedication (steroids and antihistamines) prior to the procedure, and 3 developed recurrent ADRs. All three patients had a history of Grade III reactions to ICM at the initial event. Despite premedication and the use of an alternative ICM, Grade II ADRs occurred in two patients. In the remaining patient, the same ICM was re-administered after premedication, resulting in cardiac arrest.

This study demonstrates that, despite the use of premedication—whose efficacy remains controversial—some patients may experience reactions that are more severe and life-threatening than the initial event. Additionally, a significant association was identified between baseline serum tryptase levels and reaction severity in patients with immediate-onset RCM-induced ADRs. These findings indicate that reliance on premedication or alternative contrast agents alone may be insufficient, underscoring the need for meticulous risk assessment and the development of individualized preventive strategies.